Agavaceae

Picture 1 Distribution of Agavaceae (mobot org)

Stout, simple or sparingly branche, often arborescent shrubs or even trees, seldom scandent, or often coarse, short-stemmed, more or less herbaceous plants arising from a short rhizome or erect caudex, at least sometimes with crassulacean acid metabolism, commonly with raphides or pseudoraphides and chelidonic acid, and often accumulating steroid saponins, but only seldom tanniferous (from proanthocyanins), rarely if ever cyanogenic, and not known to produce alkaloids, food reserves in vegetative organs consisting largely of polyfructosans, with out starch: vessels with secondary growth of monocotyledonous type, the vascular bunles closed and scattered.

Leaves. Simple, alternate, sessile, tending to crowded in dense rosettes at the ends of the stem and branches, or the ground-level on a short main stem, perennial and more or less strongly thickned,but usually leathery or firm-succulent, often prickly on the margins and often firmly spine-pointed, parallel-veined, but the veins commonly obscure ; stomates anomocytic or often tetracytic.

Flowers. Borne in rather massive, often dense recemes or penicles or head terminating the stems, or axillary and subterminal, perfect or sometimes unisexual (dioecious). variously pollynated by insect, birds, or bats. Trimerous throughout; tepals in 2 cycles of 3, all petaloid, often thick and fleshy, distinct or connate below to form a short or more or less elongate tube; stamens 6, the filaments distinct, adnate to the base of the tepals or to the perianth-tube; pollen-granis binucleate, monosulate, or sometimes trichotomosulcate or with 2 distal pores, gynoecium of 3 carpels united to form a compound, superior or inferior, tricular ovary with axile placentation, generally with septal nectaries, or seldom the flower without nectaries; style terminal with 3 stigma, or the stigmas sometimes sessile. Bitegmic.

Fruit. a loculucidal capcule or a berry; seed flatttened; terminal cotyledon and lateral plumule, very hard endosperm (Cronquist, 1981).