Hydriastele calcicola

Hydriastele (high-dree-Ah-STEL-eh) calcicola (kahl-see-KOH-lah)
Hydriastele calcicola. A–B. Habit. C. Portions of rachillae with triads. D. Portion of rachilla with fruit. All from Baker et al. 1096. All photos: W.J. Baker. PETER PETOE, CHARLIE D. HEATUBUN & WILLIAM J. BAKER Phytotaxa 370 (1) © 2018 Magnolia Press.
Scientific Classification
Genus: Hydriastele (high-dree-Ah-STEL-eh) Species: calcicola (kahl-see-KOH-lah)
Synonyms
None set.
Native Continent
Oceania
Morphology
Habit: Solitary Leaf type: Pinnate
Culture
Survivability index
Common names
None.

Habitat and Distribution

Distribution:—The type locality north of Kikori (Gulf Province) and sight records

Hydriastele calcicola. A–B. Habit. C. Portions of rachillae with triads. D. Portion of rachilla with fruit. All from Baker et al. 1096. All photos: W.J. Baker. PETER PETOE, CHARLIE D. HEATUBUN & WILLIAM J. BAKER Phytotaxa 370 (1) © 2018 Magnolia Press.

on the Mubi River (Southern Highlands Province; Baker 1997) of Papua New Guinea.

Habitat:—Lowland tropical rainforest river margins, on karst limestone crags, 40–500 m. PETER PETOE, CHARLIE D. HEATUBUN & WILLIAM J. BAKER Phytotaxa 370 (1) © 2018 Magnolia Press.

Description

Solitary and gregarious, moderately robust canopy palm to 30 m tall, bearing 15–20 leaves in crown. Stem about 15 cm in diam., inner wood very soft and pithy; internode 4–5 cm long. Leaf about 2.7 m long including petiole; sheath about 100 cm long, not seen close up, crownshaft about 130 × 14 cm; petiole about 60 cm long, deeply channelled adaxially; rachis strongly arcuate; leaflets about 46 per side, arranged regularly, ascending, linear, with short, widely spaced ramenta on the abaxial, basal portion of the midrib; basal leaflets comprising about 4 folds; middle leaflets about 80 × 3 cm, single-fold, obliquely to truncately praemorse apically; terminal leaflets comprising about 2 folds, truncately praemorse apically. Inflorescence about 70 cm long including 3–5 cm peduncle, branched to 2 orders, protandrous; rachillae about 26; triads on average 11 mm apart, opposite and decussate. Staminate flower 17–19 × 3–6 mm in bud, cream; stamens about 13. Pistillate flower about 6 × 2.5–3 mm in bud, cream, with free sepals and free petals with conspicuous, triangular and valvate tips. Fruit about 15 × 9 mm when ripe, obovoid to broadly ellipsoid, bright red, with a distinct, dark, sclerotic zone encircling apical stigmatic remains (up to about 3.5 mm in diam.). Seed about 10–11 × 7.5 mm, obovoid to ellipsoid; endosperm homogeneous. PETER PETOE, CHARLIE D. HEATUBUN & WILLIAM J. BAKER Phytotaxa 370 (1) © 2018 Magnolia Press. Editing by edric.

Culture

Cold Hardiness Zone: 10b

Comments and Curiosities

Notes:—Hydriastele calcicola is a moderately robust, tall palm with arching leaves and ascending leaflets. It occurs in large numbers in the Kikori River catchment (Baker, pers. obs.), where it crows gregariously on limestone outcrops (hence the species epithet). Sometimes the palm emerges directly from near-vertical limestone cliffs. We note that it also occurs at relatively low elevation compared to similar species. Hydriastele calcicola is distinguished by its pithy, non-ventricose stem, ca. 15 cm in diameter, by its leaves with deeply adaxially channelled petioles and multi-fold basal leaflets, and inflorescences with 3–5 cm long peduncles. Hydriastele calcicola is most similar to H. gibbsiana but that species is strongly ventricose and has leaves with adaxially flattened petioles and single-fold basal leaflets. PETER PETOE, CHARLIE D. HEATUBUN & WILLIAM J. BAKER Phytotaxa 370 (1) © 2018 Magnolia Press.