In praise of the colour yellow



The Montezuma oropendola (Psarocolius montezuma), of the New World blackbird family (Icteridae), is distributed in Central America, from southern Mexico south to Panama. These birds live in colonies, easily identified by the long, pendent nests, attached to branches.



Costa Rica-2
This Montezuma oropendola in Tortuguero National Park, Limón, Costa Rica, is preening its bright yellow tail feathers. (Photo copyright © by Kaj Halberg)





Costa Rica-2
As the sun sets, a fierce wind is blowing clouds over a ridge in the Cordillera de Tilarán, Costa Rica. (Photo copyright © by Kaj Halberg)





Forsythia is a genus of about 11 species in the olive family (Oleaceae), the majority of which are native to eastern Asia, and one species, F. europaea, to the Balkans. A commonly cultivated hybrid is F. x intermedia, a cross between F. suspensa and F. viridissima, which displays a profusion of yellow flowers in spring, before foliation. The genus was named in honour of Scottish botanist William Forsyth (1737-1804), who was a founding member of the Royal Horticultural Society.



Cultivated Forsythia x intermedia, Funen, Denmark. (Photos copyright © by Kaj Halberg)





Spiny-backed orb-weavers (Gasteracantha) are a genus of at least 60 species of spiders, found worldwide in warmer areas. The generic name is derived from the Greek gaster (‘belly’) and acantha (‘thorn’), referring to a number of spines, usually 6, protruding from the abdomen. These spines, as well as a shield-like carapace, covering almost the entire animal, are means of defense against enemies.

These spiders only live a few months after hatching. Females die after laying eggs, whereas the male dies a few days after inducing his sperm into the female.



Gasteracantha cancriformis is widespread in the Americas. This female was encountered on Peninsula de Osa, Costa Rica. The spines of the male are stubby. (Photo copyright © by Kaj Halberg)





The wild daffodil (Narcissus pseudonarcissus), or Lent lily, is native to western Europe, from Spain and Portugal north to Britain, and thence east to Germany. It is widely cultivated elsewhere and is a common escape from gardens.

The generic name Narcissus is often linked to the Greek myth of the youth Narkissos, who was known for his beauty. However, he admired his own reflection in a pond so much that he fell into the water and drowned. A relative of the daffodil, the narcissus (N. poeticus), sprouted where he died. According to Roman naturalist Pliny the Elder (23-79 A.D.), the plant was not named for the youth, but for its powerful fragrance, from the Greek narkao (‘I grow numb’).

The name daffodil is derived from the Greek asphodelos, a genus of plants in the family Asphodelaceae. When and why the initial ‘d’ was introduced, is not known. According to Greek mythology, daffodils grow commonly in Hades, and they are a favorite food of the dead. The name Lent lily refers to the early flowering of this species, Lent being the preparatory week before Easter.



Daffodils, escaped from a garden, Funen, Denmark. (Photo copyright © by Kaj Halberg)





Conifers, outlined against a yellowish evening sky, Yosemite National Park, Sierra Nevada, California. (Photo copyright © by Kaj Halberg)





Cutleaf coneflower (Rudbeckia laciniata), of the composite family (Asteraceae), is a native of eastern and central United States and southern Canada. Among several indigenous peoples, the leaves were formerly harvested and cooked as a vegetable.

This species has been introduced elsewhere around the world as an ornamental. It produces a large number of seeds, which can remain viable for at least three years, and it is also able to sprout from rhizome fragments. In many places, it has become invasive, including Japan, Taiwan, and some European countries.

The specific name is from the Latin lacer (‘torn’), in allusion to the deeply cut leaves, as is the first part of the common name. The generic name was applied by Swedish naturalist Carolus Linnaeus (1707-1778), also called Carl von Linné, in honour of Olof Rudbeck (1630-1702), also known by the Latinized name Olaus Rudbeckius, who was professor of medicine, and periodically rector magnificus, at Uppsala University.



In Taiwan, where these pictures were taken, cutleaf coneflower is very common, often forming large growths in open places. (Photos copyright © by Kaj Halberg)





Taiwan 2018c
Bicycles for rent in the city of Taichung, Taiwan. (Photo copyright © by Kaj Halberg)





Corn daisy (Glebionis segetum, formerly Chrysanthemum segetum) is a gorgeous composite, which is probably native to the Mediterranean region, but is today found as a weed in most of Europe, in eastern North America, in China, and elsewhere. It is also cultivated in several countries.



Thousands of corn daisies almost cover a fallow field, Vendsyssel, Denmark. (Photo copyright © by Kaj Halberg)



Wheat field with many corn daisies and cornflowers (Centaurea cyanus), central Jutland, Denmark. (Photo copyright © by Kaj Halberg)



Corn daisy with a drone fly (Eristalis tenax), Nature Reserve Vorsø, Horsens Fjord, Denmark. (Photo copyright © by Kaj Halberg)




A near relative of corn daisy is crown daisy (Glebionis coronarium), which is distributed around the Mediterranean, eastwards to Iran, and also on the Canary Islands. A yellow-flowered form resembles corn daisy, but can be identified by its deeply divided leaves. Another form has whitish ray-florets with a yellow base.



Crown daisy is extremely common on the Greek island of Crete, where it often forms large growths. (Photos copyright © by Kaj Halberg)





Bright yellow algae often cover rocks or trunks of old trees and other plants. Three examples are shown below.



Zimbabwe-Kenya 1994
Trees, silhouetted against a rock wall, covered in a yellow alga, Matobo National Park, Zimbabwe. (Photo copyright © by Kaj Halberg)



Copiapoa malletiana (formerly C. dealbata and C. carrizalensis) is a small cactus species, restricted to a limited area around Quebrada Carrizal Bajo, Atacama Desert, northern Chile, growing at altitudes between 200 and 500 m. – Pictures of many other cactus species may be studied on the page Plants: Cacti.



Chile 2011
The trunk of this Copiapoa malletiana, encountered in Parque Nacional Llanos de Challe, Atacama Desert, Chile, is overgrown by a bright yellow alga. (Photo copyright © by Kaj Halberg)



Horsechestnuts and buckeyes, genus Aesculus, are native to temperate areas of the Northern Hemisphere, with one species in Europe, which originally stems from the Balkans, c. 10 in Asia, and 7 in North America. The European horsechestnut (A. hippocastanum) is presented on the page Plants: Ancient and huge trees, whereas an American species, the California buckeye (A. californica), is dealt with on the page Plants – Mountain plants: Plants of Sierra Nevada.


Indian, or Himalayan, horsechestnut (Aesculus indica) is common in the Himalaya, from Kashmir eastwards to western Nepal, at elevations between 900 and 3,000 m. In parts of northern India, the leaves are used as cattle fodder, and the seeds are dried and ground into a bitter flour, called tattawakher. The bitterness is removed by thoroughly rinsing the flour, which is often mixed with wheat flour to make chapatis, and also halwa (sweet cakes). During hunger periods, a type of porridge, called dalia, is made from it. This species is also utilized in traditional medicine for a number of ailments, including skin problems, rheumatism, and headache. (Source: N.P. Manandhar 2002. Plants and People of Nepal. Timber Press)



The trunk of this Indian horsechestnut is partly covered by a yellow alga, Great Himalayan National Park, Himachal Pradesh, India. (Photo copyright © by Kaj Halberg)





California sister (Adelpha californica) is a butterfly of the brushfoot family (Nymphalidae), distributed from Oregon and Nevada, south through California to northern Baja California. It is easily identified by the yellow or orange patch near the wingtip.



Californien 2011
California sister, observed at Kings Canyon River, Sierra Nevada, California. (Photo copyright © by Kaj Halberg)





Yellow everlasting (Helichrysum arenarium) is widely distributed, from western Europe eastwards to Sinkiang and Mongolia, southwards to the Mediterranean and northern Iran. Formerly, in Russia, it was called ‘immortality herb’ due to its medicinal properties. Its leaves were also used as flavouring in meat dishes.



Tyrkiet 2018a
Jylland 2006-12
Yellow everlasting, photographed on the Karaburun Peninsula, near Izmir, Turkey (top), and in Mols Bjerge, Jutland, Denmark. (Photos copyright © by Kaj Halberg)





Lotus is a huge genus of the pea family (Fabaceae), comprising at least 130 species. The popular name of these plants is bird’s-foot trefoil, the trefoil part referring to the tripartite leaves, while bird’s-foot refers to their triple pods, which spread out from a common point, hereby resembling a bird’s foot.

Some DNA studies indicate that North American plants, which were formerly included in Lotus, should be placed in other genera, while other studies indicate that they should be retained in Lotus.

Four species of this genus are native to northern Europe, all presented below. They often grow in profusion in areas of low vegetation, their bright yellow flowers forming brilliant ‘carpets’.


Common bird’s-foot trefoil (Lotus corniculatus) is widely distributed in Temperate Eurasia, growing in drier habitats with low vegetation. In the Himalaya, it is found between 1,500 and 4,000 m altitude, from Pakistan east to central Nepal.



Fanø 2001-12
Fanø 2001-12
As flowers of common bird’s-foot trefoil age, they often become bright orange. These pictures are from the island of Fanø, Denmark. (Photos copyright © by Kaj Halberg)




Greater bird’s-foot trefoil (Lotus pedunculatus, formerly L. uliginosus), also called marsh bird’s-foot trefoil, grows in marshes and wet meadows. It can be identified by its broad leaflets. This species is native to Europe, North Africa, and the Middle East, and has been introduced to Australia, North and South America, and elsewhere.



Vorsø 2000-15
Greater bird’s-foot trefoil, Jutland, Denmark. (Photo copyright © by Kaj Halberg)




Narrow-leaved bird’s-foot trefoil (Lotus tenuis, also called L. glaber) is native to Europe, Russia, Siberia, Central Asia, the Middle East, and North Africa. This species is salt-tolerant, mainly growing in littoral meadows, inland in saline grasslands and lake shores. As its name implies, it has very narrow leaflets.



Sjælland 1969-2005
Narrow-leaved bird’s-foot trefoil, forming a wonderful carpet of flowers in a littoral meadow on the island of Amager, Denmark. (Photos copyright © by Kaj Halberg)




Dragon’s teeth (Lotus maritimus, by many authorities called Tetragonolobus maritimus) is native to Europe, North Africa, and Temperate Asia. Its common name stems from its sharply pointed calyx lobes. The generic name Tetragonolobus is from the Greek, tetragonus (‘square’) and lobos (‘pod’), referring to its angular pods, which are edible when young. The specific name is Latin, meaning ‘growing at the sea’.



Bornholm 2016
In Denmark, dragon’s teeth is quite rare, mainly found on the island of Bornholm, in the Baltic Sea, where this picture was taken. The orange lichen on the rock is Xanthoria aureola. (Photo copyright © by Kaj Halberg)





Golden-rain tree (Koelreuteria elegans), also called flamegold, is a smallish tree, named for its gorgeous inflorescences of countless small, yellow flowers, which, at a distance, may resemble ‘golden rain’. It is endemic to Taiwan, but is wide planted elsewhere in the tropics and subtropics as a city tree.



Taiwan 2014c
Taiwan 2013
These pictures of golden-rain tree are from the city of Taichung, Taiwan. A clearwing moth, probably of the family Sesiidae, is seen in the lower picture. (Photos copyright © by Kaj Halberg)





Emberiza is a large genus of c. 41 extant species of passerines, distributed in Europe, Africa, and Asia. Males of many species are bright yellow, such as the yellowhammer (Emberiza citrinella), which breeds in all of Europe, east to Lake Baikal and northern Mongolia, with isolated populations in Ukraine and the Caucasus Mountains, the black-headed bunting (E. melanocephala), which is found from Italy, eastwards across Turkey and the Caucasus to Iran and western Pakistan, and the black-faced bunting (E. spodocephala), breeding in southern Siberia, Mongolia, and north-eastern and south-western China.

Incidentally, the name yellowhammer is from Old English geolu (‘yellow’) and hama (‘covering’), in allusion to the bright yellow plumage of this bird.



Male yellowhammer, sitting in a white spruce (Picea glauca), Denmark. (Photo copyright © by Kaj Halberg)



Singing male black-headed bunting, Pergamon, western Turkey. (Photo copyright© by Kaj Halberg)



Singing male black-faced bunting, Lashe Hai Lake, Yunnan Province, China. (Photo copyright© by Kaj Halberg)





Rough horsetail (Equisetum hyemale), also called scouring rush, has an enormous distribution, found in North America, Europe, and northern Asia, south to Tibet, Korea, and Japan. It has also been introduced to other countries, including South Africa and Australia, where it is regarded as an invasive.

This species grows in wet areas in forests, often on slopes along streams. In Japan, it is often cultivated in ponds in ornamental gardens. Certain indigenous American tribes used a decoction of the stems for venereal diseases and as a diuretic.

The name scouring rush stems from its former usage as a scouring remedy, and as sandpaper, due to its high content of silica. The generic name is from the Latin equus (‘horse’), and seta, which has several meanings, including ‘rough’, ‘brush’, or ‘hair’. Seta can refer to the rough, silica-containing stems of these plants, but together with equus, the word means ’horse hair’. With a bit of imagination, a bunch of drying stems do resemble a horsetail.

Other Equisetum species are presented on the page Plants: Plants in folklore and poetry.



Californien 2011
This picture from Kings Canyon National Park, Sierra Nevada, California, shows the American subspecies of rough horsetail, ssp. affine, which is often yellow above each sheath. (Photo copyright © by Kaj Halberg)





In Ancient Greek mythology, three sisters, Stheno, Euryale and Medusa, were Gorgons – winged monsters with living venomous snakes on the head instead of hair. It was said that if you happened to look at any of them, you would be turned into stone. Of these sisters, Stheno and Euryale were immortal, whereas Medusa was not. She was killed by the hero Perseus, son of Zeus and Danaë, the daughter of Acrisius, who was the king of Argos.

Acrisius was dismayed that he didn’t have a son and consulted the oracle at Delphi for help. The oracle, however, warned him that he would one day be killed by his daughter’s son. To avoid her having a son, he imprisoned her in his palace, in a chamber without a roof. However, she was made pregnant by Zeus who appeared in the form of a shower of gold. Acrisius dared not invoke the wrath of Zeus by killing his offspring, but when the child was born, he placed mother and child in a wooden chest, which he sent out to sea, expecting them to perish. However, the chest washed ashore on the island of Serifos, where a fisherman named Dictys took mother and child to his home. Here, they stayed for many years, until Perseus, as the boy was named, was grown.

The king of Serifos was Polydectes, brother of Dictys. When the king saw the beautiful Danaë, he fell in love with her. Perseus, who was now an adolescent, disliked Polydectes and protected his mother from him. The king now plotted to have Perseus killed. He held a large banquet, and each guest was requested to bring a horse as a gift to the king. Perseus had no horses, so he asked Polydectes to name another gift, which he would not refuse to bring. The cunning Polydectes then demanded the head of Medusa, the only mortal Gorgon.

Perseus begged the gods for help, and they equipped him with a polished shield, a sword, winged boots, and a helm of invisibility. By viewing Medusa’s reflection in his shield, he avoided being turned into stone, and he could now safely approach the sleeping gorgon and cut off her head. Wearing his helm of invisibility, he managed to escape from the fearsome sisters of Medusa, carrying her head in a sack.

On his way to Argos, Perseus learned about the prophecy of the oracle, and as he did not want to kill his grandfather, he instead went to Larissa, where sports games were being held. Acrisius happened to be present, and Perseus accidentally hit him with his spear and killed him. Thus, the prophecy came true.



Tyrkiet 2006
Artificial light illuminates a head of Medusa, which has toppled in the underground cistern Yerebatan Sarnıcı, Istanbul, Turkey – the largest of several hundred ancient cisterns in this city, built during the reign of Emperor Justinian I (c. 482-565). (Photo copyright © by Kaj Halberg)





The coast hibiscus (Hibiscus tiliaceus) is native to islands in the Pacific and Indian Oceans, coastal Australia, Southeast Asia, the Indian Subcontinent, southern China, and Taiwan. It has also become naturalized elsewhere in tropical parts of the world. This species is mainly coastal, but may be found up to an altitude of 300 m. The specific name was given in allusion to its leaves, which resemble leaves of linden species (Tilia).



Gorgeous flower of coast hibiscus, Hu-tou Shan (‘Tiger Head Hill’), Tungxiao, western Taiwan. (Photo copyright © by Kaj Halberg)



When withering, the flowers of coast hibiscus turn orange. – Gili Air, Lombok, Indonesia. (Photo copyright © by Kaj Halberg)





Running frogs (Kassina) are a genus of brightly coloured frogs of the family Hyperoliidae, living in the entire sub-Saharan Africa. They are called running frogs, as they prefer to walk instead of hopping, like most other frogs do.

The Senegal running frog (Kassina senegalensis), also called bubbling kassina, is a common and widespread species, found from the Sahel zone of Africa, southwards to South Africa, living in a wide range of habitats, including forests, shrubland, savanna, fields, and gardens. Each male emits a popping sound, and the name bubbling kassina was given in allusion to the continuous bubbling sound, stemming from many male frogs, responding to each other’s calls.



Tanzania 1993
Senegal running frog, sitting on a bulrush stem, Ngorongoro Crater, Tanzania. (Photo copyright © by Kaj Halberg)





Most smaller herons of the genus Egretta have black legs with bright yellow toes. The generic name is from a French word, aigrette, meaning ‘little heron’.

The little egret (Egretta garzetta) has a very wide distribution, found in most tropical and subtropical areas of Europe, Africa, Asia, and Australia. In 1994, it also colonized the Caribbean island of Barbados, where a small population still exists.

Other pictures of this species, and of other herons, may be seen on the pages Animals: Birds in Taiwan, and Fishing.



Taiwan 2018
Little egret, landing in a river in Taichung, Taiwan. (Photo copyright © by Kaj Halberg)




In the New World, a near-identical relative of the little egret is the snowy egret (Egretta thula), which is distributed in South and Central America, and also in parts of North America, where some populations are migratory, wintering further south.

In 1782, the specific name of the snowy egret, thula, was given to this bird by a mistake by Chilean Jesuit priest and naturalist Juan Ignacio Molina (1740-1829), who didn’t realize, that in fact thula was the local Mapuduncun name for the black-necked swan (Cygnus melancoryphus).



USA 1998-99
Snowy egret, photographed in J.N. Darling National Wildlife Refuge, Florida. It is an immature bird, identified by the yellow line running down the back of its legs. (Photo copyright © by Kaj Halberg)





Stinging loasa (Loasa acerifolia), of the family Loasaceae, is found in the Andes Mountains. It has very pretty flowers – but do not touch this plant, as it is equipped with stinging hairs, just like the familiar stinging nettle (Urtica dioica).



Chile 2011a
Stinging loasa, Reserva Nacional Altos de Lircay, Chile. (Photo copyright © by Kaj Halberg)





The African wattled lapwing (Vanellus senegallus) is named after the yellow wattles at the base of its bill. On its wings, it has a tiny, blackish spur. This species is quite common in sub-Saharan Africa, except in areas with rainforest.



Zambia 1993
African wattled lapwing, Lochinvar National Park, Zambia. (Photo copyright © by Kaj Halberg)





Upright prairie coneflower (Ratibida columnifera) is distributed in much of North America, especially in grassy areas. The shape of its flower heads has given it the popular name ‘Mexican hat’.



USA-Canada 1992
Upright prairie coneflower, Badlands National Park, South Dakota. (Photo copyright © by Kaj Halberg)





Liocichlas are colourful birds, distributed from northern India eastwards to southern China, Taiwan, and Vietnam. Today, together with laughing-thrushes (Garrulax), sibias (Heterophasia), minlas (Minla), barwings (Actinodura), leiothrixes (Leiothrix), and others, they constitute the laughing-thrush family (Leiothrichidae).

In former days, these genera were all placed in the babbler family, Timaliidae, which was previously a true ‘waste-bin of systematics’, in which hundreds of bird species were placed. Today, most of these species have been moved to other families.


Among the liocichla species, Steere’s liocichla (Liocichla steerii), which is endemic to montane areas of central Taiwan, is the one with the most ancient lineage. At a distance, the plumage of this species appears uniformly green, but at close quarters it shows various shades of blue and brown, besides a bright yellow spot in front of the eye.



Steere’s liocichla, photographed in Dasyueshan National Forest, Taiwan. (Photo copyright © by Kaj Halberg)





Squawroot (Conopholis) only has two members, both found in North America. These plants, belonging to the broomrape family (Orobanchaceae), lack chlorophyll, obtaining nutrients by being parasitic on roots of trees. The alpine squawroot (C. alpina), or alpine cancer-root, is native to Texas, Colorado, New Mexico, Arizona, and northern Mexico. Despite the common name cancer-root, there is no evidence that it has any anti-cancer properties. A variety of this species, var. mexicana, called Mexican squawroot, is parasitic on roots of various species of pine (Pinus) and oak (Quercus). It was formerly used by indigenous tribes against tuberculosis.



Mexican squawroot, Lake Powell, Arizona. (Photo copyright © by Kaj Halberg)





Lion sculptures are often placed at Daoist graves in Taiwan, guarding the grave against evil forces. – More pictures of Daoist graves, and many other types of graves, are shown elsewhere, see Culture: Graves. Daoism is presented in depth on the page Religion: Daoism in Taiwan.



Taiwan 2012
Lion sculptures at a Daoist grave, Taichung, Taiwan. (Photo copyright © by Kaj Halberg)





The buttercup tree (Cochlospermum vitifolium), also called poro-poro, is variously placed in the families Cochlospermaceae and Bixaceae. This species is native to Central America and northern South America. Its gorgeous flowers appear after its leaves have been shed.



Costa Rica
Costa Rica
Buttercup tree, photographed in the Guanacaste Region, Costa Rica. (Photos copyright © by Kaj Halberg)





Taiwan 2013
Yellowish morning light on high-rise buildings (top), and on shops and restaurants along a street, Taichung, Taiwan. (Photos copyright © by Kaj Halberg)





The first acacia species to be dealt with scientifically was the Egyptian acacia (Vachellia nilotica), described as Acacia nilotica in 1758 by Swedish naturalist Carolus Linnaeus (1707-1778), also called Carl von Linné. Acacia is a Latinized version of the Greek word akakia, from akis (‘thorn’), referring to the prominent thorns of A. nilotica. The specific name refers to the Nile, where this species was first found.

Acacias belong to the huge pea family (Fabaceae), subfamily Mimosoideae, which is characterized by flowers with very small petals and numerous stamens. Formerly, the genus Acacia comprised no less than c. 1500 species, but according to the latest update of the Angiosperm Phylogeny Group’s classification for flowering plants, the APG IV, this genus is polyphyletic, today being divided into five genera. (Source:

Acacia, comprising c. 980 species, are mainly restricted to Australasia.

Vachellia is a genus of c. 193 tropical and subtropical species, most of which (c. 83) are found in Africa and on Madagascar

Senegalia, comprising about 220 species, are distributed worldwide in tropical and subtropical areas (except Australia), with the majority in Africa.

Acaciella is a small Neotropical genus of 15 species, most of which are found along the Mexican Pacific coast.

Mariosousa, comprising 13 species, are found mainly in Mexico and Central America, with a few species extending into the United States.

The pictures below show four acacia species, three with yellow flowers, and one with yellow bark.


Philippine acacia (Acacia confusa), also called Taiwan acacia or Formosan koa, is a small tree, growing to a height of c. 15 m. It is native to northern Philippines, south-eastern China, and Taiwan, but has been planted extensively elsewhere, including Southeast Asia and many Pacific islands. In Hawaii, it is considered invasive. It is very common in the lowlands of Taiwan, growing up to an altitude of c. 2,000 m, where it is often protected, as it helps prevent landslides and soil erosion.

Philippine acacia has no true leaves, but phyllodes – winged leaf stalks, which function as leaves. They are scimitar-shaped, up to 11 cm long and 2 cm wide, with 3-5 parallel veins. The wood is very hard and was formerly used as beams in Taiwanese underground mines. Today, it is used to make floors, and to produce charcoal. The plant is also utilized in traditional folk medicine in Taiwan.



Taiwan 2018
This Philippine acacia, displaying an abundance of flowers, was photographed near the city of Taichung, Taiwan. (Photo copyright © by Kaj Halberg)




Egyptian acacia (Vachellia nilotica), also known as gum arabic tree or babul, is native to Africa, the Middle East, and the Indian Subcontinent. It has escaped cultivation in Australia, where it is regarded as an invasive.



Nordindien 1982
Flowers of an Egyptian acacia has fallen into a pond in Keoladeo National Park, Rajasthan, India. This species, which was introduced to this reserve as breeding trees for birds, has become extremely invasive here. (Photo copyright © by Kaj Halberg)



Flowering acacia with wattled starlings (Creatophora cinereal), Kalahari Gemsbok National Park, South Africa. (Photo copyright © by Kaj Halberg)





Yellow-barked acacia (Vachellia xanthophloea) is common in eastern Africa, from Somalia south to South Africa. A popular name of this tree is fever tree, so named by early European travellers in Africa, who noticed that you would often get fever when camping beneath these trees. The reason for this is that yellow-barked acacias mainly thrive in swampy areas, where also malarial mosquitos thrive.



This picture from Lake Naivasha, Kenya, shows a close-up of the trunk of a yellow-barked acacia, on which a grey-backed fiscal shrike (Lanius excubitoroides) is sitting. (Photo copyright © by Kaj Halberg)





The male golden palm weaver (Ploceus bojeri) is bright yellow with an orange head. This bird has a fairly wide range, found in eastern Africa, from Ethiopia south to Tanzania.



Kenya 1988-89
This male golden palm weaver is displaying, sitting on a galingale stem, Meru National Park, Kenya. (Photo copyright © by Kaj Halberg)





The bladderpod (Peritoma arborea, formerly named Isomeris arborea or Cleome isomeris) is a bush in the spider-flower family (Cleomaceae), growing in the Mojave and Colorado Deserts of southern California and Baja California Peninsula. It has a foul smell, which discourages insects from eating it. Another common name of this plant is burro-fat, presumably in allusion to its butter-yellow flowers. (In Spanish, burro can mean butter, as well as donkey.)



Arizona-Utah 2001 
This picture is from Joshua Tree National Park, California, where bladderpod is very common. (Photo copyright © by Kaj Halberg)





Choughs, of the genus Pyrrhocorax, are jet-black members of the crow family (Corvidae), identified by their brightly coloured bill and feet, and by their calls, which have given them their English name. The Alpine, or yellow-billed, chough (P. graculus) is a bit smaller than the red-billed (P. pyrrhocorax), with a shorter, bright yellow bill. Both species are widely distributed in Europe, northern Africa, and Asia, the yellow-billed found in Morocco, the Pyrenees, the Alps and other Central European mountains, on Crete, and in Turkey, the Caucasus, Iran, and the Himalaya.

The red-billed chough is presented in depth elsewhere, see In praise of the colour red.



Alperne 2016
Yellow-billed choughs are often very confiding. After being drenched during a heavy rain shower, this bird is now searching for food on a restaurant table near Grossglockner, Austria. (Photo copyright © by Kaj Halberg)



Nepal 1985
A flock of yellow-billed choughs, searching for food in the Jarsang Valley, Annapurna, Nepal. (Photo copyright © by Kaj Halberg)



Annapurna 2007
Yellow-billed chough, taking off from a rock in Annapurna Sancturary, Nepal. (Photo copyright © by Kaj Halberg)





Turkish warty-cabbage (Bunias orientalis) is a member of the cabbage family (Brassicaceae), named after its warty siliques (fruits). This species is probably native to the Caucasus, central and southern Russia, western Siberia, and south-eastern Europe, north to Slovakia and Hungary. Today, however, it is very widespread in Asia, Europe, and North America, in some places regarded as an invasive.



Bornholm 2008a
Bornholm 2016a
On the island of Bornholm, Denmark, Turkish warty-cabbage is a very common escape, especially in the harbor area of the town of Gudhjem. (Photos copyright © by Kaj Halberg)





White-eyes are a group of small passerines, most of which belong to the genus Zosterops, from the Greek zoster (‘girdle’) and ops (‘eye’), referring to the white eye-ring of most species of this genus. Traditionally, they have been placed in a family of their own, Zosteropidae, but recent genetic studies indicate that they are closely related to the nine remaining genera in the babbler family, Timaliidae – previously a true ‘waste-bin of systematics’, in which hundreds of bird species were placed. (Today, most of these species have been moved to other families.) Some phylogenetic experts point out that further studies have to be made, before the true relationship of white-eyes with other birds can be determined.

The Japanese white-eye (Zosterops japonicus) has a bright yellow throat, crown, and vent, while the back is olive-green and the underside greyish. This bird is found in Japan, eastern China, Taiwan, Vietnam, and the Philippines, and it has been introduced to other areas, including Hawaii, where it is outcompeting native bird species, such as honeycreepers.



Taiwan 2018
Japanese white-eye is very common in the lowlands of Taiwan. This bird is feeding in a flower of Taiwanese cherry tree (Prunus campanulata) in the city of Taichung. (Photo copyright © by Kaj Halberg)



Taiwan 2018a
Japanese white-eye, feeding on fruits of Chinese tallow-tree (Triadica sebifera), Taichung. This tree is presented elsewhere, see Nature: Autumn. (Photo copyright © by Kaj Halberg)





Araguaney (Tabebuia chrysantha), also called ipê-amarelo (‘yellow ipê’ in Portuguese), is a native of Central America and north-western South America, widely cultivated for its abundance of bright yellow flowers, which emerge before the leaves. This species is the national tree of Venezuela, chosen because the yellow colour of its flowers resembles one of the colurs on the Venezuelan flag.



Taiwan 2015
Taiwan 2018b
Araguaney is a very commonly planted ornamental tree in warmer parts of the world. These pictures are from the city of Taichung, Taiwan. (Photos copyright © by Kaj Halberg)



Taiwan 2018b
In this picture, school children are sweeping fallen araguaney flowers in front of their school in Taichung. (Photo copyright © by Kaj Halberg)





Californien 2011a 
This huge species of kelp, several stories high, is to be seen in the gorgeous Monterey Aquarium, California. (Photo copyright © by Kaj Halberg)





The orange weaver ant (Oecophylla smaragdina) has a wide distribution, found in India, Southeast Asia, and the Philippines, south through Indonesia to northern Australia. The name weaver ant stems from their nest, which is made by ‘weaving’ together leaves, using larval silk. A colony of these ants may include several nests in a single tree, or the nests may be spread over several adjacent trees. In one instance, a colony occupied 151 nests, distributed among 12 trees. A colony may count up to half a million individuals. Each colony has a single queen in one nest, from which her progeny is carried to other nests. (Source:, with a list of references).



Cambodia 2010
Orange weaver ants, sitting on their nest, Siem Reap, Cambodia. (Photo copyright © by Kaj Halberg)





Yellow barleria (Barleria oenotheroides), also called giant yellow shrimp plant, belongs to the acanthus family (Acanthaceae). Of the nearly 300 types of Barleria, it is the only indigenous species in the New World, found in Mexico, Central America, and Colombia.



Costa Rica
Yellow barleria, observed in Parque Nacional Palo Verde, Costa Rica. (Photo copyright © by Kaj Halberg)





The yellow-headed blackbird (Xanthocephalus xanthocephalus) belong to the New World blackbird family (Icteridae). The male is black with a bright yellow head and breast, while the female is brown with a yellowish breast. This bird is found in western United States, breeding in cattail marshes (Typha). The generic as well as the specific name is from the Greek xanthos (’yellow’) and kephalos (’head’).



USA 1992
This male yellow-headed blackbird marks his territory by singing from a fence post in eastern California. (Photo copyright © by Kaj Halberg)





Yellow fairy cups (Bisporella citrina), also called lemon discos, is a sac fungus, belonging to the family Helotiaceae. It has an almost worldwide distribution, being very common on dead tree trunks.



Yellow fairy cups is especially conspicuous in autumn, here photographed in Jutland, Denmark. (Photo copyright © by Kaj Halberg)





Lemon (Citrus limon) and other citrus fruits are dealt with in depth on the page Plants: Plants in folklore and poetry.



Egypten 1999
Lemon tree, Wadi Feiran, Sinai, Egypt. (Photo copyright © by Kaj Halberg)





An abundance of butterflies, of the genus Dixeia, family Pieridae, sucking moist from wet sand on a dirt road, Meru National Park, Kenya. (Photo copyright © by Kaj Halberg)





Yellowheads, or fleabanes (Inula), comprising about 100 species of the composite family (Asteraceae), are found in Europe, Africa, and Asia. British yellowhead (Inula britannica), also called meadow fleabane, is indigenous to parts of Europe and northern Asia, and is also locally naturalized in North America.



Sverige 2015
Peacock (Aglais io), feeding in flowers of British yellowhead, Öland, Sweden. (Photo copyright © by Kaj Halberg)





The desert spiny lizard (Sceloporus magister) is native to the Chihuahuan and Sonoran Deserts of North America. It is easily identified by its rough scales and the yellow spots on its sides.



USA 1992
Desert spiny lizard, Grand Canyon, Arizona. (Photo copyright © by Kaj Halberg)





Yellow-billed blue magpie (Urocissa flavirostris) is a gorgeous member of the crow family (Corvidae), distributed in the Himalaya, south-western China, and northernmost Thailand and Vietnam. It feeds mainly on large insects and other invertebrates, but is also a notorious plunderer of eggs and young from smaller birds’ nests.



Yellow-billed blue magpie, Khumbu, eastern Nepal. (Photo copyright © by Kaj Halberg)





Evening-primroses (Oenothera) are American plants. In the late 1800s, in an area around the mouth of the Elbe River, northern Germany, a powerful mutation took place in an introduced species. In 1905, it was described as a new species, named Oenothera ammophila (’sand-loving’), which was later changed to O. oakesiana. This new species quickly spread northwards to Denmark, and today it is found along the entire west coast of peninsula Jutland.



Fanø 2001-12
Oenothera oakesiana, photographed on the island of Fanø, Denmark. (Photo copyright © by Kaj Halberg)





In autumn, the foliage of quaking aspens (Populus tremuloides) adds vivid splashes of yellow to numerous areas in western North America. This species, which is also called by many other names, including golden aspen and trembling poplar, is the most widely distributed tree in North America, found from Alaska southwards through western Canada and the United States to central Mexico, and in a broad belt across Canada and northern U.S. to Newfoundland and New England.



Californien 2011
Californien 2011
Californien 2011
Californien 2011
Quaking aspens on a mountain slope near Conway Summit, Sierra Nevada, California. The lower two pictures show the snow-white trunk of this iconic species. (Photos copyright © by Kaj Halberg)





Myanmar 2007
Buddhist pagodas in morning mist, Bagan, Myanmar. – Read more about these pagodas and other Buddhist structures on the page Religion: Buddhism. (Photo copyright © by Kaj Halberg)





Yellow pond-lilies (Nuphar) are a genus of about 10 species of water plants with pretty flowers and floating leaves, widespread in temperate and subtropical areas in the Northern Hemisphere.



Taiwan 2012
Taiwan yellow pond-lily (Nuphar shimadai) is a Taiwan endemic, growing in marshes and ponds, here photographed in Guantian Jacana Reserve, near Madou, southern Taiwan. (Photo copyright © by Kaj Halberg)





Tyrant flycatchers, family Tyrannidae, occur throughout the Americas. Comprising more than 400 species, these birds constitute the largest bird family.



Guatemala 1998
In this picture from Monterico, Guatemala, three members of the tyrant-flycatcher family are shown. Two of these are bright yellow, the great kiskadee (Pitangus sulphuratus) (lower part of the picture) and the tropical kingbird (Tyrannus melancholicus) (upper part, right). The birds with long tails are scissor-tailed flycatchers (Tyrannus forficatus). (Photo copyright © by Kaj Halberg)





The stonecrop, or orpine family, Crassulaceae, which includes stonecrops (Sedum) and roseroots (Rhodiola), among other genera, are characterized by plants with succulent leaves – an adaptation to growing in dry areas with little water. This family, which includes c. 35 genera with about 1,400 species, is found worldwide, with the greatest diversity in the Northern Hemisphere and in southern Africa.

Stonecrops (Sedum) are creeping plants, which grow in dry areas, such as in sand, among scree, or on rocks. This genus, counting about 470 species, is mainly distributed in the Northern Hemisphere, but is also found in southern Africa and in South America.



Bornholm 2008a
Biting stonecrop (Sedum acre), growing among coastal rocks on the island of Bornholm, Denmark. This species is named after the bitter, peppery taste of its leaves, caused by their content of slightly toxic alkaloids. (Photo copyright © by Kaj Halberg)





The poppy family (Papaveraceae) is dealt with in depth elsewhere, see In praise of the colour red. Below, a number of species with yellow flowers are presented.


The wonderful genus Meconopsis, comprising c. 43 species, is mainly restricted to China and the Himalaya. Many species are cultivated as ornamentals in the West. The generic name is from the Greek mekon (‘moon’) and opsis (‘resembling’), referring to the round, yellow petals of the Welsh poppy, which French botanist Louis Viguier (1790-1867) separated from the genus Papaver in 1814, calling it Meconopsis cambrica, mainly due to the structure of its style.

However, a phylogenetic study from 2011 suggests that the Welsh poppy is closer related to Papaver species than to other species of Meconopsis, restoring the former name of the species, Papaver cambricum, which was published in 1753 by Swedish naturalist Carolus Linnaeus (1707-1778), also called Carl von Linné. (Source: J.W. Kadereit, C.D. Preston & F.J. Valtueña. Is Welsh Poppy, Meconopsis cambrica (L.) Vig. (Papaveraceae), truly a Meconopsis? New Journal of Botany, Vol. 1, 2011, pp. 80-88)


The gorgeous Meconopsis paniculata, growing to a height of almost 2 m, is found in the Himalaya, from Uttarakhand eastwards to south-eastern Tibet. It is very common, especially on nutritious soils, such as cattle grazing grounds.



Rolwaling 2004
This photograph shows a very lush mountain meadow in the Rolwaling Valley, central Nepal. Meconopsis paniculata is blooming next to my guide Ganga Thapa, and also in the background. Other plants include a tall umbellifer, Pleurospermum benthamii, a red lousewort, Pedicularis megalantha, and various ferns. (Photo copyright © by Kaj Halberg)




Nepal 2002
Much hybridization takes place among Himalayan poppies. It is not clear, whether Meconopsis dhwojii, here photographed in Langtang National Park, central Nepal, is to be considered a hybrid or a full species. (Photo copyright © by Kaj Halberg)




As described above, the Welsh poppy (Papaver cambricum) was formerly regarded as belonging to the Himalayan poppies (Meconopsis). This species is restricted to montane areas of the Iberian Peninsula, southern France, south-western England, Wales, and Ireland.



Frankrig-Spanien 2007
Welsh poppy, photographed at Col d’Aubisque in the French Pyrenees. (Photo copyright © by Kaj Halberg)




The ice poppy (Papaver croceum), which was formerly regarded as a subspecies of the Siberian poppy (P. nudicaule), is a Central Asian plant, distributed from southern Siberia south to the northern outskirts of the Himalaya, and from Kyrgyzstan east to northern China.



Kirgisien 1999
Ice poppy, growing on a mountain pass above the Yrdyk Valley, Kyrgyzstan. (Photo copyright © by Kaj Halberg)




The Alpine poppy (Papaver alpinum) is divided into at least 8 subspecies, some of which are sometimes treated as full species. This species is widespread in Europe, found in the Pyrenees, the Alps, the Balkan Mountains, the Carpathians, and the Tatra Mountains. Most subspecies have yellow or orange flowers, whereas some have white.



The Rhaetian poppy (P. alpinum ssp. rhaeticum) is native to eastern Switzerland, Austria, and northern Italy. By some authorities, it is regarded as a full species, P. aurantiacum. This one was photographed at Passo di Valparola, Dolomites. (Photo copyright © by Kaj Halberg)




Horned poppies (Glaucium) are named after their horn-shaped fruits. This genus, comprising 20-25 species, has its stronghold in the Mediterranean region, and is also found in temperate Europe, North Africa, the Middle East, and Central Asia. These plants have attractive red, orange, or yellow petals. An orange-red species may be seen on the page In praise of the colour red.

As its name implies, the yellow horned poppy (Glaucium flavum) has yellow flowers. This species, which often grows on seashores, is native to Europe, North Africa, the Middle East, and the Caucasus.



Fanø 2001-12
Fanø 2001-12
Yellow horned poppy is rare in Denmark, mainly growing along the west coast of Jutland, here on the island of Fanø, where it is quite common. (Photos copyright © by Kaj Halberg)




About 32 species of prickly poppies, genus Argemone, are distributed in North America and the West Indies, with a single species endemic to Hawaii. As its name implies, the Mexican prickly poppy (A. mexicana) is a native of Mexico, but has been widely naturalized in many parts of the world.



Indien 2003
Mexican prickly poppy, naturalized in Gujarat, India. (Photo copyright © by Kaj Halberg)




Californian bush-poppy (Dendromecon rigida) occurs along the North American west coast, from northern California south to Baja California. This species is one of the few shrubby members of the poppy family, found on drier mountain slopes up to an altitude of c. 1,800 m. It is partial to newly burned areas.



Californien 2013
Californien 2013b
Californian bush-poppy, photographed in Pinnacles National Park (top), and in Torrey Pines State Park. (Photos copyright © by Kaj Halberg)





Plants of the genus Calochortus can be divided into three distinct groups: mariposa tulips, or mariposa lilies, which have open, wedge-shaped petals; globe lilies with globe-shaped flowers; and cat’s ears and star tulips, which have erect, pointed petals. These gorgeous lilies are almost exclusively found in the western United States. The generic name is from the Greek kalos (‘beautiful’) and chortos (‘grass’).

Other pictures of these beautiful lilies may be seen on the page Quotes on nature.



Arizona-Utah 2001 
Yellow form of Kennedy’s mariposa tulip (Calochortus kennedyi), Colossal Cave Mountain Park, Arizona. (Photo copyright © by Kaj Halberg)





The Canary bird (Serinus canaria) is a native of the Canary Islands, Madeira, and the Azores. In the 1600s, sailors brought the first specimens to Europe, where they quickly became popular as cage birds due to their beautiful song. Through mutations, a number of colour varieties have evolved, including yellow, white, red, brown, and bronze. The wild form is yellowish-green with grey parts on the sides and wings.

Many people think that the Canary Islands were named after this bird. However, this is not the case. Roman historian Pliny the Elder (23-79 A.D.) relates that these islands were populated by large wild dogs, for which reason they were referred to as the Canaria Islands, from the Latin canis (‘dog’). Thus, the bird is actually named after the islands – not the other way around!



Kanariske Øer 2006
Wild Canary bird, photographed on the island of Tenerife, Canary Islands. (Photo copyright © by Kaj Halberg)





Yellow, or coastal, sand-verbena (Abronia latifolia) is a member of the four o’clock family (Nyctaginaceae), growing along the North American west coast. Its roots are edible and were formerly eaten by members of the Chinook tribe. The name four o’clock family stems from another member of the family, the Marvel-of-Peru (Mirabilis jalapa), whose flowers do not open until late in the afternoon.



Californien 2011a
Yellow sand-verbena, California. (Photo copyright © by Kaj Halberg)





The red-and-yellow barbet (Trachyphonus erythrocephalus) is aptly named, as its plumage is predominantly red and yellow. This gorgeous bird is found in East Africa, from South Sudan, Ethiopia and Somalia, south to northern Tanzania. Its feathers are used ornamentally by several tribal peoples, including the Masai.



Tanzania 1993
Red-and-yellow barbet is often quite confiding, as this bird, sitting on the shaft of a shovel in our camp, Tarangire National Park, Tanzania. (Photo copyright © by Kaj Halberg)





In the Greek, rhododendron means ‘rose tree’. However, these trees and shrubs are not at all related to roses, but belong to the heath family (Ericaceae). From a distance, however, the flower clusters of certain species somewhat resemble roses. Rhododendron is a very large genus, comprising c. 1,025 species worldwide, the largest concentrations encountered in China, the Himalaya, Malaysia, Borneo, and New Guinea.

Many more species of rhododendron are presented on the page Plants: Rhododendrons.



Everest 2010 
Rhododendron campylocarpum, identified by its pale-yellow flowers, is very common in the Khumbu region of eastern Nepal, where this picture was taken. (Photo copyright © by Kaj Halberg)





The golden crocus (Crocus chrysanthus) is native to the Balkans and Turkey, but is widely cultivated due of its gorgeous flowers.



Golden crocus, naturalized at a roadside, Møn, Denmark. (Photo copyright © by Kaj Halberg)





Violets (Viola) are a huge genus, comprising maybe 600 species, found in most parts of the world, with the largest concentration in the northern temperate zone. Most violet flowers are white or various shades of blue, but some species have bright yellow flowers. Five examples are shown below.


Arctic yellow violet (Viola biflora) has a very wide distribution, found in Europe, Siberia, Central Asia, the Himalaya, China, Korea, Japan, and western North America.



Alperne 2016a
Arctic yellow violet, photographed in the Dolomites, northern Italy. (Photo copyright © by Kaj Halberg)




California golden violet (Viola pedunculata) grows in grasslands, chaparral and woodlands along the Californian coast, and in the coastal ranges up to an altitude of c. 1,000 m, south to northern Baja California.



Californien 2013b
California golden violet, Santa Rosa Plateau Ecological Reserve, California. (Photo copyright © by Kaj Halberg)




Viola wallichiana is fairly common in humid forests of the Himalaya, from central Nepal east to Bhutan and south-eastern Tibet.



Everest 2010
Viola wallichiana, photographed in the Khumbu area, eastern Nepal. (Photo copyright © by Kaj Halberg)




Viola maculata grows in forests of the Andes, from south of Santiago, Chile, and the Neuquén Province, Argentina, south to Tierra del Fuego. It is also found in the Falkland Islands (Islas Malvinas). Formerly, this species was used by the Mapuche tribe as a stimulant, for skin problems, and as a lavage in eye diseases.



Chile 2011a
Viola maculata, observed in Parque Nacional Conguillio, Chile. (Photo copyright © by Kaj Halberg)




Redwood violet (Viola sempervirens) is a native of coniferous forests along the American west coast, north to British Columbia. It can be identified by its leathery leaves. As its name implies, it often grows in forests of Californian redwood (Sequoia sempervirens).



Californien 2013
Redwood violet, Julia Pfeiffer Burns State Park, California. (Photo copyright © by Kaj Halberg)





Pitcher-plants are carnivorous plants of five different genera, which have one character in common: their leaves are highly modified, creating tube-shaped traps, called pitchers, which contain fluid. These plants emit fragrance, luring insects and other tiny animals into the trap. If these animals do not drown in the fluid, they are prevented from escaping by various means. Glands produce enzymes which can extract nutrients from the prey.

One genus of pitcher-plants is Sarracenia, comprising 11 species, which are distributed in eastern North America, from Newfoundland and Labrador in the north to Florida in the south, and westwards to the Great Lake area.

Read more about Sarracenia and other flesh-eating plants on the page Plants: Carnivorous plants.



USA 2012
Yellow pitcher-plant (Sarracenia flava), Carolina Beach State Park, North Carolina. (Photo copyright © by Kaj Halberg)





The gorgeous Shwedagon Pagoda is an enormous Buddhist shrine in Yangon, Myanmar. Especially in the evening, many local Buddhists come to this pagoda to pray, give offerings, or participate in cleaning the surrounding platform. Read more about this pagoda at Religion: Buddhism.



Myanmar 2007
The platform, surrounding the Shwedagon Pagoda, is illuminated by the evening sun. (Photo copyright © by Kaj Halberg)



Myanmar 2007
When this picture was taken, one of the lesser Shwedagon pagodas was undergoing renovation, and a bamboo scaffold had been erected around it. (Photo copyright © by Kaj Halberg)





Great yellow gentian (Gentiana lutea) is a native of montane areas of central, southern, and eastern Europe. Its root contains one of the most bitter-tasting substances known. A few drops of gentian-root tincture will stimulate the function of liver and pancreas, and also increase the appetite. The name gentian derives from King Gentius, who ruled in Ancient Illyria 181-168 B.C., and who allegedly discovered the medicinal value of the yellow gentian.

The medicinal usage of this plant is dealt with on the page Traditional medicine, whereas many other gentian species are presented on the pages Plants – Mountain plants: Himalayan flora, Flora of the Alps, and Tibetan flora.



Alperne 2017
Great yellow gentian is very common in Switzerland. This picture is from the Lauterbrunnen Valley, Berner Oberland. (Photo copyright © by Kaj Halberg)



Alperne 1968-2001
Close-up of yellow gentian flowers, Säntis Mountain, Sankt Gallen, Switzerland. (Photo copyright © by Kaj Halberg)





Clouded yellows (Colias) are colourful members of Coliadinae, called sulphurs or yellows, a subfamily of butterflies, counting about 300 species worldwide, within the huge family whites (Pieridae).

The common clouded yellow (Colias croceus) has a very wide distribution, from southern Europe and North Africa, through the Middle East to northern India.



Frankrig-Spanien 2007
Common clouded yellow, feeding on a red star-thistle (Centaurea calcitrapa), Navarra, Spain. (Photo copyright © by Kaj Halberg)




The eastern pale clouded yellow (Colias erate) is distributed from south-eastern Europe across Asia to Japan and Taiwan, and in Africa south to Somalia.



Nepal 1987
Mating pair of eastern pale clouded yellow, of the subspecies lativitta, Langtang National Park, central Nepal. This subspecies is restricted to the Himalaya. (Photo copyright © by Kaj Halberg)





Rabbitbrush, or chamisa (Chrysothamnus), are 9 shrubs in the composite family (Asteraceae), found in western parts of Canada and the United States, eastwards to South Dakota and Nebraska.

The most widespread species is the yellow, or sticky, rabbitbrush (C. viscidiflorus), occurring from British Columbia and Montana south to California and New Mexico. This species is a typical colonizer of disturbed habitats, such as burned land, landslides, and areas prone to flooding.

The generic name is from the Greek chrysos (‘golden’) and thamnos (‘bush’), referring to the golden-yellow flowers of these plants, while the specific name is from the Latin viscum (birdlime, made from mistletoe), and floro (‘flower’), thus ‘sticky-flowered’.

Yellow rabbitbrush was utilized medicinally by a variety of indigenous peoples, among the Paiute to treat colds and cough, and among the Hopi for skin problems. Gosiute and Paiute produced chewing gum from latex of the roots, while Hopi and Navajo made orange and yellow dyes from the flowers.



Californien 2011
Yellow rabbitbrush, Sequoia National Forest, Sierra Nevada, California. (Photo copyright © by Kaj Halberg)





Greater yellowlegs (Tringa melanoleuca) is a common bird in North America. It is very similar to the greenshank (Tringa nebularia), which replaces it in the Old World.



Arizona-Utah 2001
Greater yellowlegs, feeding in the Salt River, near Phoenix, Arizona. (Photo copyright © by Kaj Halberg)





Black-eyed Susan (Thunbergia alata) is a vine of the acanthus family (Acanthaceae). It is native to East Africa, but is widely cultivated as an ornamental, and it has escaped and become naturalized in most warmer regions of the world. This species is included in the Global Compendium of Weeds and is regarded as an aggressive invasive plant in a number of countries, including the United States, Costa Rica, Cuba, Brazil, Colombia, Paraguay, Australia, Japan, and Taiwan, besides numerous islands in the Pacific.

The name Black-eyed Susan is thought to stem from a character, who figures in many traditional ballads and songs. In Ballad of Black-eyed Susan, by John Gay (1685-1732), Susan goes aboard a ship in-dock to ask the sailors, where her lover William has gone. She says:


O! Where shall I my true-love find?
Tell me, ye jovial sailors, tell me true,
if my sweet William sails among the crew.


Incidentally, the name Sweet William was given to another plant, Dianthus barbatus, a species of pink, or carnation.

The generic name was given in honour of Swedish botanist and physician Carl Peter Thunberg (1743-1828), a pupil of the famous Carolus Linnaeus (1707-1778), also called Carl von Linné. Thunberg is mainly known for his botanical work in South Africa and Japan.

A near relative of black-eyed Susan, the blue trumpet-vine (Thunbergia grandiflora), is described on the page In praise of the colour blue.



Taiwan 2017a
Taiwan 2016a
These pictures of black-eyed Susan are from Taiwan, where this species is extremely common. (Photos copyright © by Kaj Halberg)





Lupines (Lupinus) is a large genus of the pea family (Fabaceae), comprising more than 200 species, mainly distributed in the Americas, but also some species around the Mediterranean and in North Africa. According to Collins English Dictionary, the common, as well as the generic name of these plants, stems from the Latin lupinus (‘wolfish’), referring to an old belief that these plants would ravenously exhaust the soil.

Yellow bush-lupine, or tree-lupine (Lupinus arboreus), is endemic to California, but is widely cultivated elsewhere as an ornamental, and also to curb the sand in wandering dunes. In many places, it has escaped and become a noxious weed, including western Europe, Turkey, Australia, New Zealand, and southern South America.



Californien 2011a
Yellow bush-lupine, Andrew Molera State Park, California. (Photo copyright © by Kaj Halberg)





The attractive yellow trumpetbush (Tecoma stans) has many other names, including yellow bells, yellow elder, and Ginger Thomas. This species is widely distributed in the Americas, from south-western U.S., south through the Caribbean and Central America to the northern half of South America. As it is widely cultivated as an ornamental, it is today found in most tropical and subtropical countries. It is the official flower of the U.S. Virgin Islands, and also the floral emblem of the Bahamas.

This species was first described as Bignonia stans by Swedish naturalist Carolus Linnaeus (1707-1778), also called Carl von Linné, but was moved to the genus Tecoma in 1819 by French botanist Antoine Laurent de Jussieu (1748-1836). It seems that he made a mistake, as he named it after what he thought was the Aztec name of the plant, tecomaxochitl, which, however, is the name of another member of the bignonia family, the calabash tree (Crescentia cujete).



Myanmar 2007 
Yellow trumpetbush, Bagan, Myanmar. (Photo copyright © by Kaj Halberg)





Seeking shelter under an umbrella, this Buddhist monk in Anuradhapura, Sri Lanka, is waiting for the rain to stop. (Photo copyright © by Kaj Halberg)





Hornbills, of the family Bucerotidae, got their name from a strange protuberance, or casque, on the bill of the larger species. These large species are very noisy, and the casque probably increases the volume of their call. The smaller species do not have this casque.

These remarkable birds are presented in detail on the page Animals: Hornbills.



Sydafrika-Namibia 1993 
Southern yellow-billed hornbill (Tockus leucomelas), Etosha National Park, Namibia. – This national park and other places in Namibia are presented on the page Countries and places: Namibia – a desert country. (Photo copyright © by Kaj Halberg)





Taiwan 2010
This extremely hairy caterpillar is very well camouflaged, sitting on a yellow leaf, Malabang National Forest, northern Taiwan. (Photo copyright © by Kaj Halberg)





Irises are a genus of wonderful plants of the family Iridaceae, comprising 250-300 species. They are named after Iris, the Greek goddess of the rainbow, presumably because of the colourful flowers of many of the species.

Yellow iris (Iris pseudacorus) is native to Europe, western Asia, and north-western Africa, and is also a common escape in North America. The specific name, meaning ‘false acorus’, refers to the similarity of its leaves to those of sweet flag (Acorus calamus).

In former days, the root was boiled together with ferrous sulphate, producing a black liquid, which was used as ink. In his book Utkast till svenska växternas naturhistoria (1867-1868), Swedish botanist C.F. Nymann (1820-1893) writes, ”It is said that the root is effective against rabies, caused by the bite of a mad dog.”



United Kingdom 1992-2002
United Kingdom 1992-2002
Yellow iris, growing in the Avon Canal, Vale of Pewsey, Wiltshire, England. (Photos copyright © by Kaj Halberg)





Leaf mustard (Brassica juncea), also known as brown mustard, Chinese mustard, Indian mustard, Oriental mustard, or vegetable mustard, is widely cultivated, especially in Asia, where it constitutes a very important vegetable, divided into the main groups leaf mustard, curled-leaf mustard, cut-leaf mustard, large-petiole mustard, head mustard, oil-seed mustard, root mustard, multishoot mustard, and big-stem mustard. (Source:



This picture shows a leaf mustard field in southern Nepal. When the crop is ripe, men will spend the night in the watchtower, shooing away wild boar (Sus scrofa), rhinos (Rhinoceros unicornis), spotted deer (Axis axis), and other grazers from the field, using burning torches. The tree to the left is a silk-cotton tree (Bombax ceiba), whose branches have been lopped for fodder. (Photo copyright © by Kaj Halberg)





European hazel (Corylus avellana) is found in the major part of Europe, eastwards to the Ural Mountains, Caucasus, and the Alborz Mountains of northern Iran. Read more about this species elsewhere, see Nature: Autumn.



The yellow catkins of European hazel emerge early in spring, in mild winters already in February. This picture is from central Jutland, Denmark. (Photos copyright © by Kaj Halberg)





The western yellow-legged gull (Larus michahellis) is found in the Mediterranean Sea. This species resembles the widespread herring gull (L. argentatus), but can be identified by its yellow legs and very powerful beak. It often breeds on house roofs, and if a window is left open, it may enter to search for edibles.

This species and other gulls are presented on the page Nature: Urban nature.



Western yellow-legged gull is extremely common in Istanbul, Turkey. This one has just killed a domestic pigeon and is now eating it on a roof top. (Photo copyright © by Kaj Halberg)





The arrow-leaved balsamroot (Balsamorhiza sagittata), or Oregon sunflower, is widespread in western North America, from British Columbia and Alberta, south to California and Wyoming. It was first collected by Colonel Meriwether Lewis, on the Lewis & Clark Expedition, at the mouth of White Salmon River, Washington, in 1806.

Many Native American peoples, including the Nez Perce, Kootenai, Cheyenne, and Salish, utilized this plant as food and medicine. The root can be eaten, raw or cooked, with a balsam-like taste. The Salish people claimed that its taste was best after being baked in a fire pit for three days. Young shoots were also cooked or added to salads. Seeds were ground and formed into cakes, which could be eaten raw. As a medicinal herb, this species was mainly used for stomach problems. (Source:



USA-Canada 1992
Arrow-leaved balsamroot, Yellowstone National Park, Wyoming. (Photo copyright © by Kaj Halberg)





Dandelion (Taraxacum officinale), also known by about a hundred other names, including lion’s tooth, cankerwort, milk-witch, Irish daisy, monks-head, priest’s-crown, blowball, puff-ball, face-clock, pee-a-bed, wet-a-bed, and swine’s snout, is native to the Northern Hemisphere, but has been introduced to most other parts of the world, where it has often become naturalized.

This species is described in depth on the page Plants: Plants in folklore and poetry, whereas its medicinal usage is dealt with on the page Traditional medicine.



Vorsø 1975-87
In this picture from 1988, a former field in Nature Reserve Vorsø, Jutland, Denmark, is full of blooming dandelion. Today, however, the dandelions have long since disappeared, and the field has been taken over by other plants. You may read about the interesting vegetation succession in this reserve on the page Vorsø on my mind: Expanding wilderness. (Photo copyright © by Kaj Halberg)





The common grass yellow (Eurema hecabe, formerly known as Terias hecabe) is a member of the huge family whites (Pieridae). This butterfly is widely distributed in Asia, Africa, and Australia, living in shrubland and open grassy areas.



Nepal 2009-2
This newly hatched common grass yellow is still sitting on its cocoon. It was observed near Pokhara, Nepal. (Photo copyright © by Kaj Halberg)




(Uploaded March 2017)


(Latest update July 2019)