Hydriastele procera (Blume) Baker & Loo (2004: 67)

Petoe, Peter, Heatubun, Charlie D. & Baker, William J., 2018, A monograph of Hydriastele (Areceae, Arecaceae) in New Guinea and Australia, Phytotaxa 370 (1), pp. 448-450 : 448-450

21. Hydriastele procera (Blume) Baker & Loo (2004: 67) . Kentia procera Blume (1838: 65) . Areca procera (Blume) Zipp. ex Blume (1843: 95) . Gronophyllum procerum (Blume) Moore (1963: 265) . Type:— INDONESIA. West Papua Province: Triton Bay, 1828, Zippelius s.n. (holotype L!)

Figure 46 (line drawing). Figure 47 (photo plate). Figure 35 (map).

Solitary and gregarious, robust palm to 30 m tall, bearing 10–15 leaves in crown, crown spherical. Stem 20–30 cm in diam., moderately ventricose; internode 6–25 cm long. Leaf (1–) 2–4 m long including petiole; sheath ca. 100 cm long, with some white bloom, crownshaft not seen; petiole 15–20 cm long, flattened adaxially; rachis straight or slightly drooping; leaflets 40–61 per side, arranged regularly, single-fold, pendulous, linear; with ramenta attached to the basal portion of the abaxial side of the midrib; middle leaflets 70–90 × 3–4 cm, acuminate to briefly bifid apically; terminal leaflets acuminate to briefly bifid apically. Inflorescence 55–90 cm long including 7–12 cm peduncle, branched to 2 or 3 orders, protandrous; rachillae 23–40, ca. 2–3 mm in diam.; triads 6–7 mm apart, opposite and decussate; ca. 6 inflorescences present. Staminate flower 14–16 × 3–5 mm in bud (when dry); stamens 6. Pistillate flower ca. 6–6.5 × 3 mm in bud, with free sepals and free petals with conspicuous, triangular and valvate tips. Fruit 10–15 × 6–7 mm when ripe (and dry), ellipsoid, with a distinct, dark, sclerotic zone encircling apical stigmatic remains (up to ca. 3.5 mm in diam. when dry). Seed ca. 9.5 × 5 (when dry), ellipsoid; endosperm homogeneous.

Distribution:— West Papua Province in western New Guinea.

Habitat:— Limestone cliffs and crags, 0–200 m.

Uses:— Flooring.

Vernacular names:— None recorded.

Conservation status:— Data deficient (DD). More data are needed about the range and abundance of this species.

Specimens examined:— INDONESIA. West Papua Province: Triton Bay, 1828, Zippelius s.n. (L!); Kaimana Regency , Kaimana Distr. , Kroy village , 110 m, 3°37’S, 133°44’E, 7 May 2001, Mehen SM 21 (MAN, K!); Raja Ampat Regency, Waigeo Island , Rabia strait, 6 m, 0°14’S, 130°50’E, 28 June 1997, Maturbongs 532 (MAN, K!); Raja Ampat Regency, Gam Island , Durumangkintus, limestone forest behind Yenbeser village , 0°27’58.88”S, 130°40’33.3”E, 5 October 2011, Heatubun 1133 (MAN, K!) .

Notes:— Hydriastele procera is a tall and robust palm with a moderately ventricose trunk that often occurs gregariously on limestone. The species is distinguished by its spherical crown of more-or-less straight leaves in combination with protandrous inflorescences (ca. six inflorescences are present at any given time) with relatively slender rachillae (ca. 2–3 mm in diam.), staminate flowers with six stamens, and relatively large fruits (10–15 × 6–7 mm when dry). Hydriastele procera is most similar to H. wosimiensis , but that species has up to 26 inflorescences, thicker rachillae (ca. 3.5 mm in diam.), staminate flowers with 12 stamens and smaller fruits (7.5–9.5 × 5–5.5 mm when dry).

Figures

FIGURE 35. Distribution map of the Longispatha group of Hydriastele in New Guinea and adjacent islands.

FIGURE 46. Hydriastele procera. A. Leaf apex. B. Mid-leaf portion adaxial side. C. Mid-leaf portion abaxial side. D. Infructescence in part. E. Portion of rachilla with triads. F. Staminate flower. G–H. Pistillate flower whole and in longitudinal section. I. Fruit whole and in longitudinal section. Scale bar:A–D = 8 cm; E, I = 7.5 mm; F = 5 mm; G–H = 3.3 mm.A–D, I from Maturbongs 532; E–H from Heatubun 1133. Drawn by Lucy T. Smith.

FIGURE 47. Hydriastele procera. A–C. Habit.All from Triton Bay, western New Guinea. All photos: Charles Humfrey.