Genera

The genus Pycnospatha belongs to Araceae. This genus has very unique appearance and that is very similar to the genus Dracontium. It contains 2 species from mainland southeast asia.

Description

❶
 Pyenospatha Thorel ex Gagnepain, Bull. Soc. Bot. France 88: 512. 1941. TYPE: P. palmata Thorel ex Gagnepain [Type: Laos: Ben-chom,
Sedom, Thorel 2404 (holotype, P).]
 Cormous herbs with solitary highly dissected leaves on spiny spongy petioles, emerging from the cataphylls early as in Dracontium species; posterior lobes forked 3 times, anterior lobe trifid, the central member trifid again, the laterals unequally forked; leaflets sessile, ± confluent, with brochidodromous pinnate venation, or the leaf entire with the anterior lobe trisect with a pair of opposite lateral lobes, and the posterior lobes 1 x pedatifid; rachides with scattered leaflets throughout. Inflorescence solitary, accompanying the leaf, peduncle much shorter than the petiole; spathe sharply hood-forming, purple with pale longitudinal streaks; spadix sessile or shortly stipitate. Flowers hermaphrodite throughout, atepalate; stamens 6+; ovary unilocular, uniovulate with basal to subbasal placentation, style elongated, stigma punctiform. Fruit a reddish spiny berry ca. 1 cm diam. (Fig.7), pericarp (in spirit material) hard, rather corky, firmly appressed around the seed. Seed black or very dark brown, seed coat hard, thick, warty, containing white druses in "tegmic" layer of pachychalaza (Figs. 5d, 6d).

❷
 Small to large, slender to robust, seasonally dormant herbs. Stem a subglobose tuber. Leaves 1-2 together; petiole smooth, rough or aculeate, mottled, sheath very short; leaf blade tri-partite to 'dracontioid', anterior division simple to trifid, segments simple to pinnatifid posterior divisions simple to bifid to pedatifid, segments then simple to pinnatifid, ultimate lobes decurrent, ovate-elliptic to triangular, acute to acuminate; primary lateral veins pinnate, running into distinct marginal vein; higher order venation reticulate. Inflorescence solitary, appearing before or with leaf; peduncle much shorter than petiole, although predominantly epigeal, similar in appearance and texture to petiole; spathe margins not overlapping, upper spathe strongly hooded, thick, marcescent; spadix much shorter than spathe, conical to ovoid-conoid, stipitate, fertile to apex; flowers bisexual, perigone absent; stamens ca 6 or more per flower, free, crowded densely together with those of neighbouring flowers; filaments oblong, flattened, connective slender; thecae oblong-ellipsoid, dehiscing by apical, pore-like slits; gynoecium elongate-flask-shaped, ovary 1-locular, ovule 1, anatropous to hemianatropous, funicle short, placenta basal to subparietal, stylar region greatly elongated, straight or somewhat curved, projecting well beyond stamens; stigma small, scarcely or no broader than style. Fruit a globose berry, pericarp densely covered with conical prickles or smooth, with conspicuous, persistent style remnant, dark green.
Seeds reniform, black or very dark brown, testa hard, thick, verrucose.
 Two species of seasonally dormant tuberous-stemmed geophytic herbs with complex umbrella-like leaves superficially similar to (although ontogenetically quite distinct from) those of Amorphophallus. Despite the overall similarity of Pycnospatha (especially P. arietina) to various Amorphophallus species, they are not at all closely related. Two species in Thailand.

❸
HABIT: seasonally dormant herbs with subglobose tuber. LEAVES: 1-2. PETIOLE: smooth, rough or aculeate, mottled, sheath very short, inconspicuous. BLADE: dracontioid, i.e. trisect, anterior division trifid, segments simple to pinnatifid, posterior divisions bifid to pedatifid, segments then simple to pinnatifid, ultimate lobes decurrent, ovate-elliptic to triangu-lar. acute to acuminate; primary lateral veins pinnate, running into distinct marginal vein, higher order venation reticulate. INFLORESCENCE: solitary, appearing before or with leaf. PEDUNCLE: much shorter than petiole, similar in appearance and texture to petiole. SPATHE: margins not overlapping, strongly fornicate, thick, # purple, marcescent. SPADIX: much shorter than spathe, conic to ovoid-conoid, stipitate, fertile to apex, flowering sequence basipetal. FLOWERS: bisexual, perigone absent. STAMENS: ca. 6 or more per flower, free, crowded densely together with those of neighbouring flow-ers, filaments oblong, flattened, connective slender, thecae oblong-ellipsoid, dehiscing by apical, pore-like slit. POLLEN: monosulcate, ellipsoid to oblong, medium-sized (mean 34 um.), exine subreticulate to rugulate. GYNOECIUM: elon-gated-flask-shaped, ovary 1-locular, ovule 1, anatropous to hemianatropous, funicle short, placenta basal to subparietal, stylar region greatly elongated, straight or somewhat curved, projecting well beyond stamens, stigma small, scarcely or no broader than style. BERRY: globose, pericarp densely covered with conic prickles, with conspicuous, persistent style rem-nant, dark green. SEED: reniform, black or very dark brown, testa hard, thick, verrucose, containing white druses, embryo large, ellipsoid to slightly curved, endosperm very sparse, only a few cell layers thick.

Distribution

Native to:
Mainland Southeast Asia

Ecology

Pycnospatha arietina
sandy soil in open places in dry semi-evergreen tropical forest, elsewhere(Thailand) in seasonally dry bamboo forest. 90-450m

Pycnospatha palmata
 Pycnospatha pafmata grows in Thailand in a deciduous forest (dipterocarp forest) in half shade on the forest floor, in sandy loam with gravel which is usually covered with leaf litter, and the plants are often found between rocks. Fruiting was at least in October (after M. Sizemore) and flowering time is from July to September (after Thorel's manuscript) and also in October (Sizemore, pers. comm.).

Etymology¹⁸

Pycnospatha (Greek) from
pyknos = compact, thick
spathe = spathe

Species

Two species belong to this genus.
❶Pycnospatha arietina

❷Pycnospatha palmata