Hydriastele ramsayi (Becc.) 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

25. Hydriastele ramsayi (Becc.) Baker & Loo (2004: 67) . Gulubia ramsayi Beccari (1910: 159) . Kentia ramsayi (Becc.) Beccari (1913: 148) . Gronophyllum ramsayi (Becc.) Moore (1963: 265) . Type:— AUSTRALIA. Northern Territory: Port Essington, Ramsay s.n. (holotype MEL!, isotype FI)

Figure 55 (line drawing). Figure 56 (photo plate). Figure 57 (map).

Solitary, robust palm to 30 m tall, bearing 9–17 leaves in crown. Stem 30–35 cm in diam., moderately ventricose. Leaf 1.5–3 m long including petiole; sheath ca. 100 cm long; petiole 30–80 cm long; rachis arcuate; leaflets 50–60 per side, arranged regularly, single-fold, ascending, linear acuminate to shallowly notched, ramenta lacking; middle leaflets ca. 80 × 2.5 cm. Inflorescence 50–60 cm long including 3.5–4.5 cm peduncle, branched to 2 orders, protandrous; prophyll often ± sigmoid, with pithy keels; rachillae ca. 31–32, not markedly sinuous; triads on average 5–6 mm apart, opposite and decussate. Staminate flower ca. 13 × 4 mm in bud (when dry), cream; stamens 5–6, exposed in bud. Pistillate flower ca. 5 × 4 mm in bud (when dry), green to cream, with free sepals and free petals with conspicuous, triangular and valvate tips. Fruit 12 × 6 mm (when dry), ellipsoid, red, with a distinct, dark, sclerotic zone encircling apical stigmatic remains (up to ca. 2 mm in diam.). Seed not seen; endosperm homogeneous.

Distribution:— The central northern portion of Australia’s Northern Territory including the Cobourg Peninsula and Melville Island. Also reported from the north eastern portion of the territory ( Dowe 2010).

Habitat:— Open eucalypt woodland dominated by seasonal drought and frequent wildfires, on sandstone slopes or flat ground on sandy soil, lowland.

Uses:— None recorded

Vernacular names:— None recorded

Conservation status:— Least Concern (LC). Hydriastele ramsayi has a relatively wide distribution (EOO> 92,000 km 2) and the AOO (552 km 2) is likely to be a low estimate due to an incomplete occurrence record.

Specimens examined:— AUSTRALIA. Northern Territory: Liverpool R. area, 25 May 1980, Craven 5918 (MEL, L!); Coburg Peninsula, Smith Point, 11°8’S, 132°9’E, 18 October 1971, Must 834 (K!, L!); 4 miles SE of Raffles Bay , 11°20’S, 132°26’E, 18 July 1961, Chippendale 8191 (K!); NW side of Cadwell R., ca. 25 km SE of Maningrida, 12°10’S, 134°25’E, 31 October 1973, Rodd 2921 (K!); Same locality as preceding, 12°10’S, 134°25’E, 31 October 1973, Rodd 2922 (K!); Arnhem Land, Oenpeilli, 12°18’S, 133°4’E, 1 October 1948, Specht 1113 (K!) .

Notes:— Hydriastele ramsayi is the only member of Hydriastele endemic to Australia. It is an emergent palm distinguished by its robust, moderately ventricose stem, arching leaves with single-fold terminal leaflets that are shallowly notched at their tips, and protandrous inflorescences branched to 2 orders. In addition, the prophyll is often distorted, and the staminate flowers congenitally open, features that are shared with the Papuan H. biakensis although that species is not reported to have a ventricose stem and has protogynous inflorescence branched to 4 orders with markedly sinuous rachillae.

Hydriastele ramsayi is unusual in the genus (and Areceae in general) in occupying a seasonal, rather than everwet habitat. The species is also described in detail by Dowe (2010).

Figures

FIGURE 55. Hydriastele ramsayi. A. Habit. B. Leaf apex. C. Leaf base. D. Infructescence. E. Portion of rachilla with triads. F. Staminate flower. G. Pistillate flower whole and in section. H. Fruit whole and in section. Scale bar: A = 1.8 m; B–D = 6 cm; E = 1 cm; F = 4 mm; G = 3.3 mm; H = 7 mm. All from Specht 1113. Drawn by Lucy T. Smith.

FIGURE 56. Hydriastele ramsayi. A–B: Habit.All from Dowe 201 & 202. All photos: J. Dowe.

FIGURE 57. Distribution map of the Palauensis group of Hydriastele in Northern Territory, Australia.