Rhopaloblaste ceramica (Miq.) Burret

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

Robust, single-stemmed palm bearing up to 17 leaves in the crown to 20 m

Morphology Stem

Stem 15–29(–35) cm diam., internodes 12–14 cm basally, decreasing to 1 cm towards apex

Morphology Leaves

Leaf to 4 m long including petiole; sheath 1.2–1.5 m long; petiole 3.5–4.5 cm long; leaflets 111–120 each side of rachis, linear; mid-leaf leaflet 100–112 × 2.3–2.5 cm

Morphology Reproductive morphology Inflorescences

Inflorescence 55–130 cm long including 8–10 cm peduncle, widely spreading with basal branches strongly recurved, branched to 3 orders; primary branches ca. 16, to 75 cm long; rachillae 45–75 cm long, 4.9–7.3 mm diam. Male flower 6.5–7 × 6.5–6.8 mm at anthesis, greenish; stamens 6

Morphology Reproductive morphology Flowers

Female flower 4.3–4.7 × 7.6–7.9 mm

Morphology Reproductive morphology Fruits

Fruit 30–35 × 16–18 mm, ellipsoid-ovoid, asymmetric, yellow to red

Morphology Reproductive morphology Seeds

Seed 21–31 mm × 14–16 mm.

Distribution

Widespread from the Bird’s Head Peninsula to north-eastern New Guinea. Elsewhere distributed from Halmahera and Buru to Ceram.

Ecology

Primary and secondary forest at 35–550 m (reported at up to 900 m outside New Guinea).

Vernacular

Ansan (Nuni).

Conservation

Least Concern.

Note

Rhopaloblaste ceramica is the largest of all the species in the genus. It is easily distinguished by its large asymmetrical fruitswith a substantial cupule of persistent perianth, and the inflorescence branched to three orders with very robust rachillae. In Papua New Guinea, R. ceramica is known only with certainty from Sandaun and East Sepik Provinces. The dubious synonym R. dyscrita originates from Morobe Province (see Banka & Baker 2004), which would represent a significant range extension, but the only surviving type material (Clemens 7987, Harvard University Herbaria [A]) is too incomplete to confirm its identity with confidence. Further exploration is required to clarify the occurrence of Rhopaloblaste in eastern New Guinea.

Extinction risk predictions for the world's flowering plants to support their conservation (2024). Bachman, S.P., Brown, M.J.M., Leão, T.C.C., Lughadha, E.N., Walker, B.E. https://nph.onlinelibrary.wiley.com/doi/full/10.1111/nph.19592

Conservation

Predicted extinction risk: not threatened. Confidence: confident

Banka, R., & Baker, W. (2004). A Monograph of the Genus Rhopaloblaste (Arecaceae). Kew Bulletin, 59(1), 47-60. doi:10.2307/4111073

Type

Indonesia, Maluku, Ceram, Teijsmann & de Vriese s.n. (holotype L!; isotype BO).

Morphology General Habit

Robust canopy solitary palm bearing up to 15 - 17 leaves in the crown

Morphology Stem

Stem to 35 m tall, 15 - 29(- 35) cm diam.; surface slightly rough, brownish grey leaf scars prominent; internodes 12 - 14 cm basally, decreasing to 1 cm distally

Morphology Leaves

Leaf sheath 1.2 - 1.5 m long, pale brownish white, moderately to densely lepidote- tomentose; crownshaft 1.3 - 1.5 m long, c. 25 - 40 cm wide, dull-green; petiole 3.5 - 4.5 cm long, shallowly concave on adaxial surface; rachis 3 - 4 m long, with abundant matted dark brown scales on adaxial surface, densely lepidote-tomentose on the abaxial surface, becoming brownish with age; leaflets 111 - 120 each side of rachis, 2.5 - 3 cm apart, in one plane, pendulous, middle leaflet 100 - 112 x 2.3 - 2.5 cm, linear, tapering acutely and bifid at the apex, adaxial surface dark green with dark brown twisted scales near the base of the pinnae and along adaxial surface of midrib, abaxial surface dull green and with some lepidote tomentum

Morphology Reproductive morphology Inflorescences

Inflorescence massive, 55 - 130 cm long, with a spread of 1 - 1.5 m, divaricate, branched to 3 orders, primary branches 16, 45 - 75 cm long, with basal pair of primary branches strongly recurved; prophyll 65 - 70 x 10 - 18 cm, dark green, with dense greyish brown indumentum; peduncle 8 - 10 cm long, 7- 10 cm diam., greyish with some tomentum; robust rachillae 45 - 75 cm long, 4.9 - 7.3 mm in diameter, greyish green; flowers sunken in shallow pits formed by rachilla bracts

Morphology Reproductive morphology Flowers

Staminate flower symmetric, greenish, 6.5 - 7 mm long, 6.5 - 6.8 mm diam. at anthesis; sepals 3 - 3.1 x 3.1 - 3.3 mm, broadly elliptic; petals 6 -6.5 x 6.5 - 6.7 mm, broadly elliptic, glabrous; stamens 3.3- 4 mm long, filaments 2- 2.5 mm long, connate at the base, yellowish, anthers 2.1 - 2.3 mm long, 0.9 - 1 mm diam., elliptic; pistillode conical, 2.3 - 2.5 mm long, 1.2 - 1.3 mm diam. Pistillate flower slightly asymmetric, 4.3 - 4.7 mm long, 7.6 - 7.9 mm diam., borne throughout the rachillae; sepals 3.9 - 4 x 3.7 - 3.8 mm, rounded; petals 4.3 - 4.4 x 2.2 - 2.4 mm, elliptic; staminodes usually 4, lobes 0.8 - 0.9 x 0.7 - 0.8 mm; gynoecium 4.3 - 4.9 mm long, 4.2 - 4.5 diam., ovoid

Morphology Reproductive morphology Fruits

Fruit 30 - 35 mm long, 16- 18 mm diam., asymmetric ellipsoid-ovoid, yellow when immature, becoming red at maturity; cupule of persistent perianth 11 - 12 mm long

Morphology Reproductive morphology Seeds

Seed 21 - 31 mm long, 14 - 16 mm diam., ellipsoid-ovoid, brown; conspicuous impression over the hilum, testa brown.

Distribution

Widespread from Halmahera and Buru in the Moluccas through to Ceram, then to mainland New Guinea. In Papua New Guinea, known only with certainty from Sandaun and East Sepik Provinces in the north-western part of the country. However, the lost type of the dubious synonym R. dyscrita originates from Morobe Province in the east.

Ecology

Well drained lowland to lower montane primary rain forests. In secondary rain forests it is found in old garden areas, on broken coral to deep, loose, porous, black volcanic soil. Also on alluvial flats in deep clay soil. From 35 to 900 m above sea level.

Vernacular

Ahad (Buru dialect), Henahena (Ternate dialect), Ogulubenge (Tobaro dialect, Akelamo Oba, Maluku).

Conservation

Least concern. Though often infrequent, R. ceramica is widespread and cannot be considered threatened.

Note

Rhopaloblaste ceramica is the largest of all the species in the genus and is easily distinguished by its large asymmetrical fruits with a substantial cupule of persistent perianth, and the inflorescence branched to three orders with very robust rachillae.

Use

The shoot apex is edible. The wood is used for walking sticks, arrowheads, spear handles, and floorboards for hoCultivated as an ornamental.

Use

The shoot apex is edible. The wood is used for arrowheads and floorboards for houses. Occasionally cultivated as an ornamental.