Orontium (Araceae)
Laticifers present, simple, articulated. HABIT : seasonally dormant, aquatic herbs, continuation shoot of stem sympodium arising in axil of last foliage leaf of each article and beginning with a foliage leaf rather than a cataphyll, rhizome short, erect, buried deep in soil. LEAVES : several. PETIOLE : terete, sheath long. BLADE : oblong-elliptic, held above water surface or floating on it; primary lateral veins arising at base of blade, arcuately ascending and running into apex, secondary laterals inconspicuous and parallel to primaries, higher order venation transverse-reticulate. INFLORESCENCE : 1-2 in each floral sympodium. PEDUNCLE : absent, spadix supported on elongated stipe. SPATHE : a short, inconspicuous, simple bract, inserted at point of attachment of inflorescence to rhizome, enclosing young spadix, later separated from it and disintegrating. SPADIX : held above water level, conical, slender, flowering acropetally, golden yellow, peduncle-like stipe very long, often partly submerged, greenish to red-brown with white, swollen apical part. FLOWERS : bisexual except for some male flowers at spadix apex, perigoniate, tepals 6, sometimes 4, short, about as long as wide, fornicate, subtruncate, irregularly imbricate. STAMENS : 6, sometimes 4, filaments flattened, connective slender, thecae ellipsoid, dehiscing by broad apical slit. POLLEN : monosulcate, ellipsoid, large (mean 64 µm., range 55-73 µm.), exine densely foveolate-fossulate. GYNOECIUM : ovary depressed-globose, broader than long, 1-locular, ovule 1, hemianatropous, held horizontally, funicle short, placenta basal, style ± absent, stigma small, subsessile, discoid-hemispheric. BERRY : depressed-globose, green, 1-seeded, partially immersed in spadix axis. SEED : ± globose, testa thin, smooth, ± transparent, decaying at maturity, raphe conspicuous in furrow-like depression, hilum reddish, embryo large, almost globose to depressed-globose, with a small internal cavity situated below the hilum, outer cell layers green, plumule well-developed with 1(-2) filiform leaf primordia, endosperm absent.
Seasonally dormant aquatic herbs with short erect rhizome; petiole cylindric, leaf blade oblong-elliptic; spathe not normally visible, inserted at attachment to rhizome, stipe very long, white apically, spadix cylindric, yellow; flowers bisexual, perigoniate, with 6 tepals. Differs from Symplocarpus in inconspicuous spathe, very long stipe, cylindric spadix and basal placentation. Differs from Calla in leaf shape, presence of perigone, and in lacking ligule on petiole sheath.
E. U.S.A. to Texas.
Temperate wetlands, occurring from sea level to 900m alt.; partly submersed aquatic plant growing in open or partially shaded swamps, marshes, lakes and ponds, in dense stands or scattered colonies.