Ponapea Becc.

Baker, W.J., Barfod, A.S., Cámara-Leret, R., Dowe, J.L., Heatubun, C.D., Petoe, P., Turner, J.H., Zona, S. & Dransfield, J. (2024) Palms of New Guinea. Royal Botanic Gardens, Kew, Richmond. 726 pp.

Morphology General Habit

Slender, single-stemmed tree palm, crownshaft present, monoecious

Morphology Leaves

Leaf pinnate, strongly arching; sheath tubular; petiole present; leaflets few to numerous, reduplicate, wedge-shaped, with jagged tips, arranged regularly, horizontal-Inflorescence below the leaves, branched to 2 orders, branches spreading; peduncular bract projecting from prophyll, enclosing inflorescence in bud, prophyll (and sometimes peduncular bract) usually not dropping off as inflorescence expands; peduncle sometimes longer than inflorescence rachis; rachillae slender to quite robust, straight to curving

Morphology Reproductive morphology Flowers

Flowers in triads throughout the length of the rachillae, not developing in pits, male flowers larger than female flowers, bullet-shaped

Morphology Reproductive morphology Fruits

Fruit red, ellipsoid, stigmatic remains apical, flesh quite thick, endocarp pale to black, thin, weakly 5–grooved

Morphology Reproductive morphology Seeds

Seed 1, conforming to endocarp, endosperm ruminate.

Distribution

One species in New Britain and three species in the Caroline Islands.

Note

Ponapea is represented in the New Guinea region by the New Britain endemic species P. hentyi, a slender palm with strongly recurving leaves, wedge-shaped leaflets and an endocarp with a distinctive black, glassy inner surface. It is known from elevations up to around 700 m. It resembles Drymophloeus, although the ranges of the two genera do not overlap. Drymophloeus is immediately distinguished by its stilt roots and is generally less robust with less strongly recurving leaves. It is also similar to Ptychosperma and Brassiophoenix, which are distinguishable by their deeply, sharply lobed or angled endocarps (P. hentyi endocarps are only weakly lobed) and seeds and leaves that do not strongly recurve.

Distribution

Three species in the Caroline Islands (Pohnpei and Palau).

Biology

Found in rain forest along banks of streams at low elevations.

Vernacular

Not known.

General Description

Moderate, solitary, unarmed, pleonanthic, monoecious palm. Stem erect, moderate, smooth, grey, ringed with leaf scars. Leaves pinnate, arching; sheath forming a prominent crownshaft, abaxially densely covered with grey scales; petiole well developed, deeply channelled adaxially, rounded abaxially, covered with small brown punctiform scales; rachis channelled basally, ridged distally; leaflets broadly lanceolate, regularly arranged, tips oblique to truncate, conspicuously praemorse, adaxially glabrous, abaxially covered with numerous dark brown ramenta on major veins, transverse veinlets not apparent. Inflorescences infrafoliar, held horizontally, branched to 4 orders basally, to 2–1 orders distally; peduncle short, rather slender, flattened, glabrous; prophyll tubular, membranous, bearing scattered scales, rounded at the tip, splitting abaxially allowing the peduncular bract to emerge; peduncular bract borne just above the prophyll, exceeding the prophyll, longitudinally splitting, caducous, bearing scales as the prophyll; peduncular bract tubular, caducous, shortly beaked, splitting abaxially, adaxially glabrous, abaxially densely to lightly covered in stellate brown scales, scar of 1 incomplete peduncular bract present; rachis much longer than the peduncle, elongate, tapering, bearing rather widely spaced ± angled first-order branches, each subtended by a very small, ridge-like bract; rachillae white, slender, spreading, somewhat divaricate and zig-zag, glabrous, bearing subdistichous, distant triads of flowers for 2/3 their length and paired to solitary staminate flowers distally; floral bracteoles large, low, rounded. Staminate flowers symmetrical, bullet-shaped; sepals 3, distinct, broadly imbricate, irregularly rounded, somewhat gibbous; petals 3, distinct, ovate, valvate, evenly thickened, adaxially grooved; stamens ca. 100, filaments erect in bud, short, awl-shaped, anthers oblong-elliptical, curled, deeply bifid basally and apically, dorsifixed near the base, ?latrorse, connective broad, tanniniferous; pistillode conical, much shorter than the stamens. Pollen ellipsoidal asymmetric; aperture a distal sulcus; ectexine tectate, finely perforate-rugulate, aperture margin similar or slightly finer; infratectum columellate; longest axis 43–51 µm [1/3]. Pistillate flowers ovoid; sepals 3, distinct, imbricate, rounded, margins variously split; petals 3, distinct, broadly ovate and imbricate, tips thick, valvate, opening briefly apically to expose the stigmas at anthesis; staminodes 3, irregular, tooth-like; gynoecium asymmetrical, ovoid with a bulge on one side, unilocular, uniovulate, stigmas 3, fleshy, recurved at anthesis, ovule very large, laterally attached, form unknown. Fruit ovoid when fresh, drying irregularly 5-ridged, red at maturity, stigmatic remains apical, perianth persistent; epicarp smooth, becoming somewhat striate when dry, mesocarp fleshy, endocarp thick, black, conspicuously 5-ridged (Ponapea leddermanniana), ridged and straw-coloured (P. hosinoi), or terete and straw-coloured (P. palauensis). Seed attached laterally, ovoid, conforming to the shape of the endocarp, hilum elongate, raphe branches anastomosing, endosperm homogeneous; embryo basal. Germination adjacent-ligular; eophyll bifid with broad conspicuously praemorse lobes. Cytology not studied.

Diagnostic

Moderate, solitary pinnate-leaved palms, native to the Caroline Islands, all with crownshafts and praemorse leaflets.

Morphology

Fruit (Essig 1977).