Theriophonum Blume

CATE Araceae, 17 Dec 2011. araceae.e-monocot.org

Habitat

Tropical forest; geophytes, forest floor, grassy places, ditches, damp sites on rocky, lateritic soil.

Distribution

India, Sri Lanka.

Diagnostic

Small, seasonally dormant tuberous herbs; leaf blade oblong-lanceolate to sagittate-hastate, fine venation reticulate; spadix male and female zones separated by zone of subulate to filiform sterile organs, terminal sterile appendix smooth; flowers unisexual, perigone absent. Differs from Typhonium, Arisaema and Arum in having apical and basal placentation (basal in Typhonium and Arisaema, parietal to subbasal in Arum ).

General Description

HABIT : small, seasonally dormant herbs, tuber small, depressed-subglobose. LEAVES : several. PETIOLE : sheath relatively long. BLADE : sagittate-hastate or hastate, sometimes linear-lanceolate or oblong-ovate; primary lateral veins pinnate, forming submarginal collective vein, 1-2 distinct marginal veins also present, higher order venation reticulate. INFLORESCENCE : solitary, appearing with the leaves. PEDUNCLE : usually short, erect in flower, deflexing in fruit. SPATHE : marcescent, constricted between tube and blade, tube convolute, blade much longer than tube, erect and gaping to spreading, or sometimes ± reflexed. SPADIX : sessile, shorter or subequal to spathe, female zone few-flowered, very short, separated from male by axis partly or completely covered with sterile flowers, sterile flowers either basal, central or at apex of sterile zone, male zone cylindric, sometimes with zone of sterile flowers above, appendix stipitate or not, erect, shorter or much longer than rest of spadix, cylindric, elongate-conoid to very long-subulate. FLOWERS : unisexual, perigone absent. MALE FLOWER : 1-2-androus, anthers subsessile, connective slender, sometimes elongated and prominent, thecae ovoid, dehiscing by apical pore or broad slit. POLLEN : inaperturate, spherical, medium-sized (mean 25 µm.), exine spinose. STERILE FLOWERS : spreading, somewhat decurved or suberect, long, slender and filiform to shorter and subulate. FEMALE FLOWER : gynoecia oriented vertically, ovary ellipsoid to obovoid, 1-locular, ovules 3-9 (or more), orthotropous, funicle short, placentae 2, apical and basal, stigma ± sessile, discoid-hemispheric, sometimes rather massive with central depression. BERRY : ovoid to ellipsoid, few-seeded. SEED : broadly ovoid to ellipsoid, apiculate, strophiolate, testa smooth to rugose, embryo axile, elongate, endosperm copious.