The Urticaceae in the flora of Vietnam has 21 genera and about 100 species. This article presents some systematic information about major morphological characteristics (leaves, inflorescences, male flowers, female flowers, fruits and seeds). Leaves alternate or opposite, stipules present, rarely absent; leaf blades simple. Inflorescences cymose, paniculate, racemose, spicate, or cluster-capitate, usually formed from glomerules, sometimes crowded on common enlarged cuplike or discoid receptacle, rarely reduced into a single flower. Male flowers: stamens as many as and opposite to perianth lobes, filaments inflexed in bud; anthers 2-locular, opening lengthwise, rudimentary ovary often present. Female flowers: perianth lobes free or connate, usually enlarged in fruit and persistent, occasionally absent; staminodes scarious, opposite to the perianth lobes, or absent. Ovary rudimentary in male flowers, sessile or shortly stipitate, free or adnate to the perianth; 1-locular, ovule solitary, erect from the base; style simple, or absent; stigma diverse, capitate, penicillate-capitate (brushlike), subulate, filiform,ligulate, or peltate. Fruit usually a dry achene, sometimes a fleshy drupe, often enclosed by the persistent perianth. Seed solitary, endosperm usually present; embryo straight; cotyledons ovate elliptical or orbicular.
Duong Thi Hoan
(Proceedings of 3rd National Scientific Conference on Ecology and Biological Resources, Hanoi 22th October 2009 - IEBR)