Arum Family. Herbs mostly with basal long-petioled simple or compound leaves, and spatha-ceous inflorescence, the spathe enclosing or subtending a spadix. Rootstock tuberous or a corm, in our species mostly with an acrid or pungent sap. Spadix very densely flowered, the staminate flowers above, the pistillate below, or the plants wholly dioecious, or with perfect flowers in some species. Perianth wanting, or of 4-6 scale-like segments. Stamens 4-10 in our species; filaments very short; anthers 2-celled, commonly with a thick truncate connective, the sacs open-in? by dorsal pores or slits. Ovary i-several-celled; ovules i-several in each cell; style short or wanting; stigma terminal, mostly minute and sessile. Fruit a berry or utricle. Seeds various. Endosperm copious, sparse or none.

About 105 genera and 900 species, mostly of tropical regions, a few in the temperate zones. Flowers without a perianth.

Flowers monoecious or dioecious, borne at the base of the spadix.

1.

Arisacma.

Flowers monoecious, covering the whole spadix.

2.

Peltandra.

Flowers perfect.

3.

Calla.

Flowers with a perianth.

Spadix enclosed in a shell-like fleshy spathe.

4.

Spathyema.

Spadix naked, terminating the scape.

5.

Orontium.

Spadix naked, borne at the base of a leaf-like spathe.

6.

Acorus.