Oncocalamus (G.Mann & H.Wendl.) H.Wendl., Palmiers : 252 (1878)

Primary tabs

Discussion

Diagnosis

Uses

Description

  • Clustered, spiny, high-climbing, pleonanthic, monoecious, rattan palms. Stem eventually becoming bare, circular in cross-section, with long internodes. Leaves pinnate, bifid in juveniles, with a terminal cirrus; sheath strictly tubular, bearing scattered, black, bulbous-based, triangular, brittle spines and scattered, thin, caducous indumentum; ocrea conspicuous, tightly sheathing, neatly truncate, armed as the sheath; knee absent; petiole present but usually very short, absent in mature flowering stems; rachis armed with scattered spines as the leaf sheath; cirrus bearing neat pairs of reflexed acanthophylls; leaflets few to numerous, usually single-fold, sometimes with 2 or more folds, entire, acute, linear, lanceolate or somewhat sigmoid, regularly arranged, usually armed along the thickened margins with robust spines, midribs evident, other large veins rather distant, transverse veinlets conspicuous; proximal few leaflets sometimes smaller than the rest, heavily armed and reflexed across the sheathed stem. Inflorescences branched to 1 order; peduncle enclosed within the leaf sheath and emerging from its mouth, ± hemispherical in cross-section; prophyll tubular, tightly sheathing, 2-keeled, 2-lobed at its tip, much shorter than the sheath; peduncular bracts ca. 4, ± distichous, tightly sheathing at first, later splitting longitudinally, each with a short triangular lobe; rachis longer than the peduncle; rachis bracts like the peduncular, rather close; first-order branches pendulous or spreading with a basal 2-keeled tubular prophyll and numerous distichous, short, tubular, somewhat inflated, striate bracts, each enclosing a flower cluster, after anthesis eventually irregularly splitting and tattering; flower cluster partially covered by a tubular 2-keeled prophyll and consisting of up to 11 flowers arranged in a group with a central 1 or 3 pistillate flowers and 2 lateral cincinni of 2–4 staminate flowers, each flower, apart from the central pistillate bearing an open, spathulate, 2-keeled, prophyllar bracteole (the precise arrangement of the flowers not yet understood). Staminate flowers symmetrical; calyx membranous, striate basally, stalked, tubular, with 3 short triangular, apiculate lobes; corolla apparently only slightly exceeding the calyx, divided almost to the base into 3 elongate, striate, valvate petals; stamens 6, filaments united to form a thick, fleshy androecial tube, free from the corolla, tipped with 6 shallow lobes, bearing pendulous, rounded, latrorse anthers on the inside; pistillode very narrow, conical, slightly exceeding the androecial tube. Pollen ellipsoidal, bi-symmetric; aperture a distal sulcus; ectexine tectate, very finely perforate, interspersed with very small spinulae, aperture margin similar; infratectum columellate; longest axis 23–29 µm [1/4]. Pistillate flowers superficially very similar to the staminate except slightly broader; the calyx and corolla similar; staminodal tube bearing minute empty anthers; gynoecium tricarpellate, triovulate, ± ellipsoidal, covered in reflexed scales, style long, narrow, 3-angled, ovule form unknown. Fruit ± spherical, stigmatic remains minute, conical, apical; epicarp covered in vertical rows of rather thin reflexed scales, mesocarp very thin, almost obsolescent at maturity, endocarp not differentiated. Seed single, basally attached with an oval hilum, covered with a ?thick sarcotesta and endosperm homogeneous, laterally deeply penetrated by a smooth-margined mass of inner seed coat; embryo lateral opposite the intrusion. Germination and eophyll unknown. Cytology not studied. (J. Dransfield & N. Uhl & C. Asmussen & W.J. Baker & M. Harley & C. Lewis, Genera Palmarum. The evolution and classification of palms. 2008)A
  • Clustered, spiny, moderate to high-climbing, pleonanthic, monoecious rattan palms. Stem circular in cross section, with short to medium internodes; sucker shoots axillary. Leaves pinnate, strongly bifid in juveniles, with a terminal cirrus; sheath strictly tubular, bearing scattered, brown or black, bulbous-based triangular, brittle spines, sometimes becoming bare, and scattered, thin, white, caducous indumentum; ocrea conspicuous, tightly sheathing, neatly horizontally truncate, lobed or somewhat saddle-shaped, armed as the sheath, spines often concentrated on ocrea margin; knee absent, although rounded horizontal swelling visible at the base of the leaf in some species; leaves sessile, or with a very short flattened petiole; rachis unarmed or sparsely to profusely armed on the underside; cirrus bearing reflexed acanthophylls; elaminate rachis co mmon on lower part of stems, bearing equidistant, alternate to opposite acanthophylls; spear leaf deep orange to bright crimson to light green; leaflets few to numerous, usually single-fold, sometimes with 2-4 folds, entire, acute, linear, lanceolate or sigmoid, regularly arranged, usually armed along the thickened margins with robust spines, less so distally, midribs evident, other large veins rather distant, transverse veinlets conspicuous, proximal few leaflets smaller than the rest, often erect, vertical to rachis and stiffly swept back across stem or arching and somewhat pendulous. Inflorescences produced in axils; peduncle enclosed within the leaf sheath and emerging from its mouth, hemisperical or flattened and rectangular in cross-section; prophyll tubular, tightly sheathing, 2-keeled, 2-lobed at its tip, much shorter than the sheath; peduncular bracts ca.4, ± distichous, tightly sheathing at first, later splitting longitudinally, each with a short triangular or straight lobe; rachis longer than the peduncle; rachis bracts like the peduncular, rather close; rachillae pendulous with a basal 2-keeled tubular prophyll and numerous distichous, short, tubular, somewhat inflated, striate bracts, each enclosing a flower cluster, eventually longitudinally splitting and tattering post anthesis; flower cluster partially covered by a tubular 2-keeled prophyll and consisting of 5, 7, 9 or 11 flowers arranged in a group; 1-3 pistillate flowers in the centre subtended by 2 lateral cincinni of 0-2 pistillate and 2-4 staminate flowers, each flower, apart from the central pistillate, bearing an open, spathulate, 2-keeled, prophyllar bracteole. Staminate flowers symmetrical; calyx membranous, striate basally, stalked, tubular, with 3, short, triangular, apiculate lobes; corolla enclosed or only slightly exceeding the calyx, divided almost to the base into 3, elongate, striate, valvate petals; stamens 6, filaments united to form a thick fleshy, androecial tube, free from the corolla, tipped with 6 shallow lobes, bearing pendulous, rounded, latrorse anthers on the inside; pollen elliptic, monosulcate, with scabrate, tectate exine; pistillode very narrow, conical, slightly exceeding the androecial tube. Pistillate flowers superficially very similar to the staminate except slightly broader; calyx and corolla similar; staminodial tube bearing tiny empty anthers; gynoecium tricarpellate, triovulate, ± ellipsoidal, covered in reflexed scales, style long, narrow, 3-angled; ovule basally attached, anatropous. Fruit ± spherical, stigmatic remains minute, conical; epicarp covered in vertical rows of rather thin reflexed scales, mesocarp very thin, almost obsolescent at maturity, endocarp not differentiated. Seed single, ± rounded, smooth or warty, basally attached with an oval hilum, covered with a thin, papery, sweet sarcotesta; endosperm homogenous, laterally penetrated by a smooth-margined mass of inner seed coat; embryo lateral opposite the intrusion. Germination adjacent-ligular; eophyll bifid, petiole of seedling dull reddish pink. (T.C.H Sunderland, A taxonomic revision of the rattans of Africa (Arecaceae: Calamoideae) in Phytotaxa 51. 2012)B

Relationships