Metroxylon amicarum (H.Wendl.) Becc.
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Authority
Henderson, A. & Borchsenius, F. 1999. Evolution, variation, and classification of palms. Mem. New York Bot. Gard. 83: i-xi, 1-324, color pls. I-XIII.
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Family
Arecaceae
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Scientific Name
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Description
Species Description - Pleonanthic trees, (6-) 12-33 m tall. Stem 30-36 cm diam. Leaves 4-7 m long; sheathing leaf base unarmed or armed with single to multiple spines, occurring as clusters, or combs or upon collars, spines 1-1.5 cm long; petiole 1-3 m long, occasionally armed with spines in juveniles, commonly unarmed in adults but occasionally with collars; rachis unarmed; leaflets 87-127 X 7.2-12 cm, regularly arranged to grouped, usually unarmed on the margins and midvein, occasionally armed with 0.5-7 cm long spines along the main vein. Inflorescences branching to second order, interfoliar; peduncle 0.5-1.1 m long, 2.8-5.5 cm diam., erect; one to rive peduncular bracts, unarmed; rachis bracts unarmed, first-order branches erect or horizontal with up to eight rachillae per first-order branch; rachillae 8-16 cm X 11-15 mm , bearing 300-750 flowers, cylindrical, with a short proximal, bare to densely brown pubescent, stalklike portion, and two to eight empty bracts proximally and zero to two empty bracts distally, the rest each enclosing a dyad of flowers; floral prophylls spirally arranged in four to six rows. Staminate flowers 3 mm diam.; calyx 4-7 mm long, with three sepals; corolla 6-9 mm long, with three woody, valvate petals; corolla > 2 X as long as the calyx; stamens 3-5 mm long; pollen elliptic, disulcate, with a scabrate, foveolate, or smooth, tectate exine. Hermaphroditic flowers 3 mm diam.; calyx (4-)6-7 mm long, tubular, three-lobed, with three valvate, woody to basally sepals; corolla (6-)7- 11 mm long, tubular, rounded to three-lobed, with three woody, valvate petals; corolla > 2 X as long as the calyx; stamens 4-8 mm long; pollen with a scabrate, foveolate, or mcoarsely reticulate exine; gynoecium 2-7 mm long. Fruit rounded, (5.3-)7.2-8.3(-13) cm diam., 5.6-13 cm long; epicarp covered in 26-38(-40) rows of golden to chocolate brown and gray-margined, reflexed scales, with midfruit scales 7-14 mm long, mesocarp 2-12 mm thick, fibrous, corky or spongy; endocarp thin if present. Seed globose or occasionally obpyriform, 4.2-5.5 cm diam., invaginated to 3 cm deep.
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Discussion
Metroxylon amicarum (H. Wendl.) Becc, Ann. Roy. Bot. Gard. (Calcutta) 12(2): 187. 1918. Sagus amicarum H. Wendl., Bot. Zeit. 36(8): 115. 1878. Type: Unknown locality, Reichenbach s.n. 1878 (holotype: B). Fig. 5B Metroxylon carolinense (Dingier) Becc, Denkschr. Kaiserl. Akad. Wiss., Math.-Naturwiss. Kl. (Rechinger ed.), 84: 60, fig. 5a & d. 1913. Coelococcus carolinensis Dingier, Bot. Zentr. Bl. 32: 349, t. 2. 1887. Type: Caroline Islands: Ponape, Schneider 1327 (holotype, B; isotypes, B). Metroxylon amicarum (H. Wendl.) Becc. var. majus Becc, Ann. Roy. Bot. Gard. (Calcutta) 12(2): 188. 1918. Type: Unknown locality, Gibbon 1189 (holotype: B). Metroxylon amicarum (H. Wendl.) Becc. var. commune Becc, Ann. Roy. Bot. Gard. (Calcutta) 12(2): 188. 1918. Type: Caroline Islands: Ponape, Ledermann 13409 (holotype: B-n.v., presumably destroyed; isotype: BISH). Common names: Ivory nut palm, oahs (Pohnpei), rupang (Chuuk), oj (Marshall Islands). Although this species is apparently widely distributed over a number of small islands, very few collections exist. The palm fruits are still harvested as a source of vegetable ivory for carvings sold to tourists and young plants are sold to Japan as office plants. Available herbarium materials reflect to some extent this tradition of usage as an ornamental and as a source of ivory; that is, many of the specimens cited are from cultivated ornamentals or are collections of one or more fruits brought to Europe as novelties. Many additional collections of fruits are available at B, but most of these have little or no collection data with them. Fl also has several sets of fruit collections that were used by Beccari in preparing his manuscripts. These fruits are rather extreme in size and do not reflect the norms. Fruits observed on Pohnpei and in several islands of the Chuuk atoll varied widely in size and shape, including obpyriform-shaped fruits not encountered in previous herbarium specimens. Beccari (1918) described two varieties on the basis of indigenous classifications of differing leaf sizes. Beccari indicated that variation in leaf size probably formed a continuum, and he was correct. Ledermann 13409 was not to be found among the collections at B, BM, Fl, or K, but was found at BISH. It seems unlikely that Wendland or Beccari based their descriptions upon a collection in Hawaii, so it is assumed that the original type has been lost or destroyed and that the collection at BISH represents the only remaining isotype. One tree, 33 m tall, was cut down (McClatchey 1163) and examination of the leaves revealed that at such heights, they are greatly reduced, the leaflets fragile, and the petiole vagina extending into the rachis almost to the tip of the leaf. The overall appearance of the leaves was that of the first few bracts subtending an inflorescence of M. warburgii. Perhaps M. amicarum merely has a very extended hapaxanthic inflorescence persisting because of continuous growth of leaves that educe to bracts as the flowering branches are produced. Measurements of these reduced leaves are not included in the description above since they appear to be part of a continuous trend, possibly ending in greatly reduced bracts. Of the species of sect. Coelococcus, M. amicarum is the most phenetically distinctive and is easily circumscribed due to its pleonanthic condition. The trees are also the tallest, reaching 33 m or possibly taller.
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Distribution
Distribution: Caroline Islands (Federated States of Micronesia, states of Pohnpei and Chuuk [Truk]), the Marshall Islands, and formerly in G u a m and Palau. (Although specimens collected in G u a m and Palau are available, I could not locate these trees on those islands and native foresters indicated that the trees have not been present for at least 20 years.)
Oceania|