Hemithrinax Hooker

Henderson, Andrew, 2023, A revision of Coccothrinax, Hemithrinax, Leucothrinax, Thrinax, and Zombia (Arecaceae), Phytotaxa 614 (1), pp. 1-115 : 91-92

2. Hemithrinax Hooker in Bentham & Hooker (1883: 930).

Type:— Trithrinax compacta Grisebach & Wendland in Grisebach (1866: 221) (= Hemithrinax compacta (Grisebach & Wendland) Hooker ex Salomon )

Thrinax subgenus Hemithrinax (Hooker in Bentham & Hooker) Drude (1889: 34).

Type:— Hemithrinax compacta (Grisebach & Wendland) Hooker ex Salomon.

Hemithrinax section Macrocarpae Muñiz in Muñiz & Borhidi (1982: 312) . Thrinax subgenus Hemithrinax section Macrocarpae (Muñiz) Borhidi & Muñiz (1985: 226) .

Type:— Hemithrinax rivulalris León .

Hemithrinax section Hemithrinax Muñiz in Muñiz & Borhidi (1982: 312). Thrinax subgenus Hemithrinax section Hemithrinax (Muñiz) Borhidi & Muñiz (1985: 226) .

Type:—Not designated.

Stems 1.0 m long and 8.3 cm diameter, solitary. Leaves more or less deciduous or only leaf bases persisting on stem; leaf sheaths split at the base; leaf sheath fibers 1.0(0.1–2.3) mm diameter, stout, woody, separating into long, single, curled fibers, or few, single, or wiry, separating into curled, multi-fiber strands; petioles 14.8(10.3–22.6) mm diameter just below the apex; palmans 30.9(10.7–51.0) cm long, relatively long, without prominent adaxial veins; interfold filaments present; leaf blades not wedge-shaped; segments 41(26–53) per leaf, the middle ones 68.2(38.0–102.0) cm long and 4.2(2.3–6.2) cm wide; segments not pendulous at the apices, giving the leaf a flat appearance; middle leaf segments relatively long and narrow with a shoulder distal to the palman apex, widest at the shoulder; middle leaf segment apices blunt and rounded or attenuate; leaf segments not waxy or sometimes with a deciduous, thin layer of wax adaxially, without indumentum abaxially, with close rows of small, whitish dots between the veins on the abaxial surface, together with fewer, larger, scattered brownish or greenish scales, without or with well-developed transverse veinlets. Inflorescences erect amongst or above the leaves with few to numerous partial inflorescences, or erect amongst or above the leaves, with few partial inflorescences at apex of inflorescence, or compact amongst the leaf sheath bases; rachis bracts tubular, closely sheathing, membranous, brown tomentose, or swollen, woody, not tomentose; partial inflorescences 5(3–9); proximalmost rachillae straight, 6.4(3.0–12.0) cm long and 1.1(0.7–1.4) mm diameter in fruit; rachillae glabrous at or near anthesis; flowers spirally arranged; stamens 6(6–8), short, forming a compact ring around the gynoecium at anthesis, the anthers extrorse; fruit pedicels 0.2(0.1–0.7) mm long; fruits 9.0(5.0–14.3) mm long and 8.8(4.5–13.8) mm diameter, yellowish; fruit surfaces smooth or sometimes with projecting fibers; seed surfaces smooth or shallowly lobed; seeds in longitudinal section intruded by the hilum from base to about half way, the apex of the intrusion rounded.

Distribution and habitat:— Hemithrinax is endemic to Cuba. Rodríguez et al. (2020) have given a detailed account of the distribution of the species in Cuba.

Key to the species of Hemithrinax

1. Leaf sheath fibers 1.6(0.8–2.3) mm diameter, stout, woody, separating into long, single, curled fibers; leaf segment apices blunt and rounded, briefly splitting; middle leaf segments 44.3(38.0–50.5) cm long; western Cuba (Villa Clara) ............. H. ekmaniana

- Leaf sheath fibers 0.5(0.1–0.8) mm diameter, few, single or wiry and separating into strands; leaf segments apices attenuate; middle leaf segments 80.2(57.0–102.0) cm long ............................................................................................................................ 2.

2. Inflorescences erect amongst or above the leaves; fruits 14.2(14.0–14.3) mm long; eastern Cuba (Holguín) ............... H. rivularis

- Inflorescences compact amongst leaf sheath bases; fruits 5.7–5.8 mm long; eastern Cuba (Holguín, Santiago de Cuba) ................ ........................................................................................................................................................................................ H. compacta