The family consists of over 250 genera and ca. 2,000
species
distributed worldwide, but most diverse in tropical and subtropical
areas.
Vegetative markers for the family include latex
production in combination with opposite leaves
that tend to be both simple and entire.
Flowers feature a 5th whorl (corona)
and he 5 stamens are adnate to the gynoecium to form a single
structure,
known as a gynostegium. The
gynoecium
consists of two nearly distinct carpels with ovaries and styles
separate
and distinct but united by a single massive stigma. Anthers,
usually
attached to the stigma, produce paired sacs of pollen called pollinia.
Pollinia from adjacent anthers are connected by 'translator
arms' which both attach to a 'gland'
producing a single unit, the pollinarium,
which is carried by the vector during pollination.
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