The plants are
annual,
biennial or
perennial herbs, woody shrubs, or trees with a caustic, poisonous milky latex. The
roots are fine or thick and fleshy or tuberous. Many species are more or less
succulent, thorny, or unarmed. The main stem and mostly also the side arms of the succulent species are thick and fleshy, and often winged, tall. The succulent trees and large shrubs are mostly confined to southern and eastern Africa, but others are found elsewhere. For example,
Euphorbia neutra is native to the
Caatinga of
Brazil and
Euphorbia royleana is found in the
Himalayan foothills. The deciduous
leaves may be
opposite,
alternate, or in
whorls. In succulent species, the leaves are mostly small and short-lived. The
stipules are mostly small, partly transformed into
spines or
glands, or missing.
Inflorescence and fruit Like all members of the family Euphorbiaceae, spurges have unisexual flowers. In
Euphorbia, flowers occur in a head, called the
cyathium (plural cyathia). Each male or female flower in the cyathium head has only its essential sexual part, in males the
stamen, and in females the
pistil. The flowers do not have
sepals,
petals, or
nectar to attract pollinators, although other nonflower parts of the plant have an appearance and nectar glands with similar roles. Euphorbias are the only plants known to have this kind of flower head. Nectar glands and nectar that attract pollinators are held in the involucre, a cup-like part below and supporting the cyathium head. The "involucre" in the genus
Euphorbia is not to be confused with the "involucre" in family Asteraceae members, which is a collection of bracts called
phyllaries, which surround and encase the unopened flower head, then support the receptacle under it after the flower head opens. The involucre is above and supported by
bract-like modified leaf structures (usually in pairs) called cyathophylls', or cyathial leaves. The cyathophyll often has a superficial appearance of being petals of a flower.
Euphorbia flowers are tiny, and the variation attracting different pollinators, with different forms and colors occurs, in the cyathium, involucre, cyathophyll, or additional parts such as glands that attached to these. The collection of many flowers may be shaped and arranged to appear collectively as a single individual flower, sometimes called a
pseudanthium in the Asteraceae, and also in
Euphorbia. The majority of species are
monoecious (bearing male and female flowers on the same plant), although some are
dioecious with male and female flowers occurring on different plants. It is not unusual for the central cyathia of a
cyme to be purely male, and for lateral cyathia to carry both sexes. Sometimes, young plants or those growing under unfavorable conditions are male only, and only produce female flowers in the cyathia with maturity or as growing conditions improve. The female flowers reduced to a single pistil usually split into three parts, often with two stigmas at each tip. Male flowers often have anthers in twos. Nectar glands usually occur in fives, may be as few as one, In contact with mucous membranes (eyes, nose, mouth), the latex can produce extremely painful
inflammation. The sap has also been known to cause mild to extreme Keratouveitis, which affects vision. Latex on skin should be washed off immediately and thoroughly. Congealed latex is insoluble in water, but can be removed with an emulsifier such as milk or soap. A physician should be consulted if inflammation occurs, as severe eye damage including permanent blindness may result from exposure to the sap. The poisonous qualities were well known: in the Ethiopian
Kebra Nagast, the serpent king
Arwe is killed with juice from the
Euphorbia.
Uses Several spurges are grown as garden plants, among them
poinsettia (
E. pulcherrima) and the succulent
E. trigona.
E. pekinensis () is used in
traditional Chinese medicine, where it is regarded as one of the
50 fundamental herbs. Several
Euphorbia species are used as food plants by the
larvae of some
Lepidoptera (butterflies and moths), like the spurge hawkmoths (
Hyles euphorbiae and
Hyles tithymali), as well as the
giant leopard moth.
Ingenol mebutate, a drug used to treat
actinic keratosis, is a
diterpenoid found in
Euphorbia peplus. Euphorbias are often used as hedging plants in many parts of Africa.
Misidentification as cacti '' Among laypeople,
Euphorbia species are among the plant taxa most commonly confused with
cacti, especially the
stem succulents. Euphorbias secrete a sticky, milky-white fluid with latex, but cacti do not. Individual flowers of euphorbias are usually tiny and nondescript (although structures around the individual flowers may not be), without petals and sepals, unlike cacti, which often have fantastically showy flowers. == Systematics and taxonomy ==