Family: Araceae
Common name: arum family [Zomlefer, pp. 301-303]
Diversity: Worldwide: 110 genera; 2,000 species
U.S.: 20 genera
PNW (Hitchcock & Cronquist): 2 genera
Flower -- Vegetative Features -- Economic Importance -- Flower Images-- Web Sites

K/Co4-6, 0 S1-6 P(1-3)
Sexuality: bisexual or unisexual
Symmetry: actinomorphic
Inflorescence: spadix (=spike of crowded flowers on fleshy axis)
Calyx (sepals)/
Corolla (petals):
4-6 separate or connate, sometimes absent (in unisexual)
Androecium: 6 separate, sometimes staminodes (=sterile stamens) also present in female flowers
Gynoecium: 1-3, united carpels, superior ovary (=hypogynous), sometimes embedded in the spadix
Fruit: berry
Other features: large, showy (petaloid) spathe (bract), found below and sometimes enclosing the spadix.

with unisexual flowers, plants usually monoecious with male flowers above female flowers in spadix

often foul (fetid) odor associated with flowers

Vegetative Features
watery or milky sap
raphides (calcium oxalate crystals) in tissue
Leaves: alternate or opposite, simple or compound, can be parallel, pinnately, or palmately veined, petiole with sheathing base, exstipulate
Life-history: perennial
Habit: herbs, rarely woody, some epiphytes
Distribution & Ecology: mostly tropical, some temperate
some species are marsh plants
Some Northwest Genera: Acorus, sweet flag
Lysichitum, skunk cabbage

Economic Importance
Crops: tropical species often grown for tubers
(e.g. Colocasia = taro)
Ornamentals: houseplants: Dieffenbachia dumbcane; Philodendron Zantedeschia, arum lily, calla lily
Weedy and pest species:

Examples Arisaema
click on the genus name for a flower image

Links to Other Web Sites

International Aroid Society
Krzysztof Kozminski's Araceae Links