of
Euphorbia baylissii The
leaves are alternate, seldom opposite, with
stipules. They are mainly simple, but where compound, are always
palmate, never
pinnate. Stipules may be reduced to
hairs, glands, or
spines, or in succulent species are sometimes absent. The plants can be
monoecious or
dioecious. The radially symmetrical
flowers are unisexual, with the male and female flowers usually on the same plant. As can be expected from such a large family, a wide variety exists in the structure of the flowers. The
stamens (the male organs) number from one to 10 (or even more). The female flowers are
hypogynous, that is, with superior
ovaries. The genera in tribe
Euphorbieae, subtribe Euphorbiinae (
Euphorbia and close relatives) show a highly specialized form of
pseudanthium ("false flower" made up of several true flowers) called a
cyathium. This is usually a small, cup-like
involucre consisting of fused-together bracts and peripheral nectary glands, surrounding a ring of male flowers, each a single stamen. In the middle of the cyathium stands a female flower, a single
pistil with branched
stigmas. This whole arrangement resembles a single flower. The
fruit is usually a
schizocarp, but sometimes a
drupe. A typical schizocarp is the regma, a capsular fruit with three or more cells, each of which splits open explosively at maturity, scattering the small seeds. The family contains a large variety of
phytotoxins (toxic substances produced by plants), including
diterpene esters,
alkaloids, and
cyanogenic glycosides (e.g. root tubers of
cassava). The seeds of the
castor oil plant
Ricinus communis contain the highly
toxic carbohydrate-binding protein ricin. A milky
latex is a characteristic of the subfamilies
Euphorbioideae and
Crotonoideae, and the latex of the rubber tree
Hevea brasiliensis is the primary source of natural rubber. The latex is
poisonous in the Euphorbioideae, but innocuous in the Crotonoideae. White mangrove, also known as blind-your-eye mangrove latex (
Excoecaria agallocha), causes blistering on contact and temporary blindness if it contacts the eyes, hence its name. The latex of spurge was used as a
laxative. Twenty first century molecular studies have shown that the enigmatic family
Rafflesiaceae, which was only recently recognized to belong to order
Malpighiales, is derived from within the Euphorbiaceae. Euphorbiaceae are monoecious and
open pollinated and so
self-incompatibility is rare - although it has been reported in the past, apparently this was in error. It is confirmed to be absent or incomplete in
herbaceous Chamaesyce by Ehrenfeld 1976,
Hevea by Bouharmont 1962, and
Manihot by Jennings 1963 and George & Shifriss 1967. == Taxonomy ==