Oncocalamus macrospathus Burret, Notizbl. Bot. Gart. Berlin-Dahlem 15: 749 (1942)

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Distribution

Map uses TDWG level 3 distributions (http://www.nhm.ac.uk/hosted_sites/tdwg/geogrphy.html)
Angolapresent (World Checklist of Arecaceae)B
Cabindapresent (World Checklist of Arecaceae)B
Cameroonpresent (World Checklist of Arecaceae)B
Equatorial Guineapresent (World Checklist of Arecaceae)B
Gabonpresent (World Checklist of Arecaceae)B
Zairepresent (World Checklist of Arecaceae)B
Oncocalamus macrospathus is distributed from Cameroon, south of the Sanaga River, to Cabinda (Angola). This species is more commonly encountered in coastal forest although it also occurs in the lowland riverine forests of the Congo Basin. (Dowe, J.L., A taxonomic account of Livistona R.Br. (Arecaceae))A

Biology And Ecology

  • This species is commonly found in forest margins, tree-fall gaps and other open areas and is particularly common in seasonally-inundated forest and alongside water courses. (T.C.H Sunderland, A taxonomic revision of the rattans of Africa (Arecaceae: Calamoideae) in Phytotaxa 51. 2012)C

Conservation

  • Least concern (LC). (T.C.H Sunderland, A taxonomic revision of the rattans of Africa (Arecaceae: Calamoideae) in Phytotaxa 51. 2012)C

Etymology

  • (Latin) refers to the large inflorescence bracts. (T.C.H Sunderland, A taxonomic revision of the rattans of Africa (Arecaceae: Calamoideae) in Phytotaxa 51. 2012)C

Description

  • Clustered robust palm climbing to 20-35 m. Stems without sheaths, 18-30 mm in diameter, with 28-40 mm; internodes 18-24 cm long. Leaf sheaths very lightly striate, light moderately to profusely armed with upward-pointing brown spines; armature often concentrated on the sheath apex and often sloughing off at base leaving very feint circular scars; profuse white caducous indumentum present on mature and juvenile sheaths; ocrea ± horizontally truncate, somewhat striate, sometimes with a very slight (0.5-1 cm) rounded lobe abaxial to the leaf, armed as the sheath, although spines often concentrated at apex, extending up to 3 cm. Spear leaf dull yellow to bright green. Juvenile sheaths, armed as the mature sheaths only spines more profuse; leaves bifid, soon becoming pinnate; elaminate rachis up to 2 m long. Leaves on mature stems sessile, or with short (<2.5 cm long) petiole; rachis 1.5-2.0 m long, abaxially rounded, adaxially concave, becoming trapezoid then triangular in cross section distally, armed as the sheath, spines particularly profuse on underside, sparse on upper surface; cirrus up to 1.5 m long, ± triangular in cross section, unarmed; leaflets 30-40 on each side of the rachis, lightly pendulous, composed of a single-fold, linear-lanceolate, or ± sigmoid, boadly attenuate at the base, broadly to finely acuminate at apex, 35-45 cm long × 1.5-2.5 cm broad at the widest point, concolorous, armed along the margin with robust spines, particularly at base of leaflet, single-nerved, with 5-7 conspicuous secondary nerves on each side, lowermost leaflets smaller than the rest, somewhat erect or stiffly swept back across stem; acanthophylls up to 5 cm long. Inflorescences in successive, axils, ca.3m from stem apex; peduncle 15-20 cm long; peduncular bracts ca.3-4, 6-7 cm long; rachis up to 1.2 m in length, arching, pendulous; rachis bracts 2.5-4.5 cm long; rachillae, circular in cross-section, 25-35 cm long, pendulous, bracts bright yellow prior to anthesis, becoming dry, grey; prophyll subtending flower cluster 5-7 mm long, striate. Flower cluster with one central pistillate flower subtended by two lateral cincinni with one pistillate and 3-4 staminate flowers; staminate flowers 5 mm × 3.5 mm; calyx longer than the corolla, with short (<1 mm) stalk, tubular for the basal 2 mm; corolla, enclosed within the calyx, ca.4 mm long, tubular for the basal 1 mm; staminodial tube ca.2 mm long; anthers 0.8 mm × 0.2 mm; pistillode 2 mm × 0.5 mm; pistillate flowers similar to the staminate, 3.5-4.5 mm wide; ovary, 2.5 mm × 0.8 mm, tipped with a ca.1.5 mm long style. Fruit at maturity ± globose, 1.8-2 cm., with 18-20 vertical rows of scales. Seed sub-globose, 1.5-1.8 cm × 1.6-1.9 cm, smooth, lightly flattened to depressed below; sarcotesta <0.3 mm. (T.C.H Sunderland, A taxonomic revision of the rattans of Africa (Arecaceae: Calamoideae) in Phytotaxa 51. 2012)C

Materials Examined

  • CAMEROON: Lejoly 86/1005, 3km S of L'Olonou (02º46N:12º02E), Fr., December 16, 1986 (BR!); Letouzey 4556, 35 km S of Bengbis (03º13N:12º28E), Fr., March 17, 1962 (YA!); Letouzey 11889, Mintom I (02º03N:13º30E) Fl., January 23, 1973 (K!, YA!); EQUATORIAL GUINEA: Sunderland 1913, Akonibe to Evinayong road (01º21N:10º43E) Fl. & Fr., April 2, 1998 (K!, EG!, BH!, WAG!); Sunderland 1914, Akonibe to Evinayong road (01º21N:10º43E) sterile, April 2, 1998 (K!, EG!, WAG!); GABON: Breteler et al. 10957, 5?30km NNW of Ndjale (00º05S:10º45E) Fl., April 21, 1992 (WAG!); Dibata & Mbouissou 958, Mission Otouma (00º13N:10º56E) Fr., February 10, 1992 (BR!); Louis et al. 1350, 32km SE of Sindera (01º14S:10º53E) Fr., July 13, 1983 (K!, WAG!, BR!, HBG); Reitsma 1340, Between Cap Santa Clara and Cap Esterias (00º34N:09º22E) Fr., August 15, 1985 (WAG!); Wieringa 466, 0.5km SE of Tchimbelé (00º36N:10º24E) Fr., January 25, 1990 (WAG!); DEMOCRATIC REPUBLIC OF CONGO: Couteaux 502, Eala (00º03N:18º18E) sterile, October 29, 1938 (BR!); Evrard 2077, Isangi (01º02N:23º41E) Fl. & Fr., December 11, 1956 (BR!); Gossweiler H1039/24, Port Congo, Fr., April 28, 1924 (K!); ANGOLA: Gossweiler 9092, Mayombe, Luali, (05º00S:12º25E) Fl. & Fr., s.d. (K!) (T.C.H Sunderland, A taxonomic revision of the rattans of Africa (Arecaceae: Calamoideae) in Phytotaxa 51. 2012)C

Bibliography

    A. Dowe, J.L., A taxonomic account of Livistona R.Br. (Arecaceae)
    B. World Checklist of Arecaceae
    C. T.C.H Sunderland, A taxonomic revision of the rattans of Africa (Arecaceae: Calamoideae) in Phytotaxa 51. 2012