Heterospathe Scheff., Ann. Jard. Bot. Buitenzorg 1: 141 (1876)

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Number of Taxa

  • 41 species

Discussion

Biology And Ecology

Etymology

Diagnosis

Description

  • Dwarf to moderate, solitary or sometimes clustered, unarmed, pleonanthic monoecious palms. Stem creeping or erect, sometimes basally expanded, grey-green to brown, leaf scars prominent. Leaves pinnate, rarely entire bifid, erect, becoming spreading, often reddish when young; sheath splitting abaxially and not forming a well-defined crownshaft, margins fibrous, acute, glaucous or not; petiole short to elongate, usually deeply channelled adaxially, rounded abaxially, variously indumentose; rachis straight or curved, basally channelled adaxially, distally ridged, rounded abaxially, variously indumentose; leaflets, when present, single-fold, acute to acuminate, prominent, midrib elevated, marginal ribs often thickened, veins adaxially ± waxy or glabrous, abaxially tomentose or brown-dotted, with or without basifixed ramenta on midrib. Inflorescences interfoliar or infrafoliar at anthesis, branched to 1–4 orders basally, fewer distally, often with reddish-brown, deciduous tomentum; peduncle prominent, elongate, elliptic in cross-section; prophyll persistent, attached near the base and completely encircling the peduncle, tubular, 2-keeled laterally, more-or-less dorsiventrally flattened, splitting abaxially, and apically; peduncular bract 1 or rarely 2 (Heterospathe trispatha), attached below or sometimes above the middle of the peduncle, terete, beaked, enclosing the inflorescence in bud, greatly exceeding the prophyll, splitting abaxially and caducous or marcescent as the inflorescence matures; rachis short to elongate, bearing spirally arranged, short, pointed bracts subtending a few simple rachillae, or several branches with basal bare portions; rachillae slender, bearing sessile or slightly depressed, spirally arranged triads subtended by spreading lip-like bracts throughout the rachillae, or with paired or solitary staminate flowers toward the apex of the rachillae; bracteoles of the staminate flowers small, bracteoles surrounding the pistillate flower 2, spreading to cupular and imbricate. Staminate flowers symmetrical or slightly to markedly asymmetrical; sepals 3, distinct, broadly imbricate and rounded, ± keeled dorsally and gibbous basally; petals 3, distinct, valvate, usually about twice as long as the sepals, prominently lined when dry, ± acute, one usually somewhat larger than the others; stamens 6–36 or more, distinct, the filaments awl-shaped and strongly inflexed at the apex, anthers oblong in outline, dorsifixed and versatile at anthesis, latrorse; pistillode either small and conical, or columnar, prominent, nearly as long as the stamens, sometimes with an expanded apex. Pollen ellipsoidal asymmetric, occasionally oblate triangular; aperture a distal sulcus, infrequently a trichotomosulcus; ectexine tectate, perforate, perforate and micro-channelled or finely perforate-rugulate, aperture margin similar or slightly finer; infratectum columellate; longest axis ranging from 26–54 µm [12/32]. Pistillate flowers symmetrical, ± same size as the staminate; sepals 3, distinct, broadly imbricate, rounded; petals 3, distinct, broadly imbricate with briefly valvate apices; staminodes 3, tooth-like; gynoecium unilocular, uniovulate, short, soft, expanded upward into a thick stylar region below 3 recurved, short stigmas, the ovule lateral at top of locule, pendulous, hemianatropous. Fruit globose to ellipsoidal, small to large, orange to red when mature, stigmatic remains apical, eccentrically apical or subapical to lateral; epicarp smooth but drying granular or with irregular lines over short sclerosomes in the thinly to thickly fleshy mesocarp, with flattened anastomosing fibres, endocarp thin, operculate, smooth, shining within, or with thickened adnate fibres, irregularly sculptured, ridged and grooved, beaked at the apex, with a mass of slender fibres within a framework of thickened fibres at the base. Seed not adherent to endocarp, globose to ellipsoidal or with angled and with 3 rounded ridges laterally and abaxially, attached apically and laterally by the elongate hilum extending nearly the length of the seed, raphe branches simple to anastomosing, endosperm ruminate or rarely homogeneous (H. longipes and H. uniformis); embryo basal. Germination adjacent-ligular; eophyll bifid where known. Cytology: 2n = 32. (J. Dransfield, N. Uhl, C. Asmussen, W.J. Baker, M. Harley and C. Lewis. 2008)

Anatomy

Relationships

  • Heterospathe is moderately to strongly supported as monophyletic (Norup 2005, Asmussen et al. 2006, Norup et al. 2006, Baker et al. in review, in prep.). The genus is moderately supported as sister to Linospadix, which was the sole representative of the Linospadicinae in a study by Lewis and Doyle (2002). Other data place Heterospathe as sister to a poorly supported clade of Dransfieldia, Linospadix and Laccospadix (Asmussen et al. 2006). (J. Dransfield, N. Uhl, C. Asmussen, W.J. Baker, M. Harley and C. Lewis. 2008)

Taxonomic accounts

Uses

Bibliography

  • Dransfield, J. , Uhl, N. , Asmussen, C. , Baker, W.J. , Harley, M. & Lewis, C. 2008. Genera Palmarum. The evolution and classification of palms. Kew Publishing, Royal Botanic Gardens Kew.