Rhopaloblaste elegans H.E.Moore

Conservation

Data deficient. While the relatively wide distribution of R. elegans in the Solomon Islands suggests that the category Least Concern may be appropriate, we know too little about the distribution of this species and the threats that it might face to make an assessment at this stage.

General Description

Moderately robust solitary mid-canopy palm bearing up to 10 - 14 leaves in the crown, with a mass of short, stout adventitous roots present at the stem base. Stem to 12 m tall or more, 15 - 20 cm diam.; surface grey- brown, becoming light grey distally, with chocolate- brown scales on new internodes, leaf scars prominent. Leaf sheath 60 - 70 cm long, light green with dense indumentum of brownish white scales; crownshaft 60 - 80 cm long, 20 - 25 cm wide; petiole short, 5 - 8 cm long, green, concave on adaxial surface, rounded on the abaxial surface; rachis 3 - 3.5 m long, with dense indumentum of shiny brownish black scales and deciduous white tomentum on the adaxial and abaxial surfaces; leaflets 70 - 76 each side of rachis, borne 3 - 5 cm apart, in one plane, semi-spreading, middle leaflet 64 - 68 x 2.7 - 3.4 cm, linear, tapering acutely and bifid at the apex, adaxial surface green, stiff, papery with prominent veins, abaxial surface pale green, with twisted, reddish brown ramenta present along abaxial surface of the mid-veins, dense black membranous scales as on rachis on adaxial surface of mid-veins near base of the pinnae, less dense on the abaxial surface. Inflorescence 30 - 45 cm long, branched to 2 orders, primary branches 15 - 16, up to 40 cm long, basal pair of primary branches strongly recurved; prophyll 35 - 40 x 5 - 6 cm, brown-silky- tomentose; peduncle 6 - 8 cm long, 6 - 7 cm diam., orange-green basally and then green distally; rachillae slender, 30 - 35 cm long, 3.2 - 3.9 mm diam., dull green. Staminate flower slightly assymmetric, 6 - 7 mm long, 4 - 4.5 mm in diam. at anthesis; sepals 2 - 2.5 x 3 - 3.5 mm, rounded; petals 5 - 6 x 3 - 3.5 mm, broadly elliptic; stamens 4.5 - 5 mm long, filaments 2 - 2.5 mm long, connate at the base, anthers 3.6 - 3.8 mm long, 0.9 - 1 mm diam.; pistillode ovoid-conical, 2.5 - 3.2 mm long, 1 - 1.2 mm in wide at the base. Pistillate flower 5 - 5.8 mm long, 4 - 4.3 mm diam. at anthesis; sepals 3 - 3.3 x 5 - 5.5 mm; petals 3.5 - 4 x 2.5 - 3 mm, broadly elliptic; staminodes 4, lobes 0.9 - 1 x 0.8 - 0.9 mm, united at the base; gynoecium 3.5 - 4 mm long, 2.8 - 3.5 mm diam., ovoid. Fruit 25 - 26 mm long, 20 - 23 mm diam., globose, yellowish green to orange when immature, with cupule of persistent perianth 4.5 - 5 mm long. Seed 17 - 21 mm long, 18 - 20 mm diam., globose, brownish, with conspicuous impression over hilum; testa brown.

Distribution

Restricted to the Solomon Islands from Choiseul and St Isabel to Guadalcanal.

Vernacular

Dai'e, Fai Dai (Kwara'ae), Auki (Angariru).

Biology

In gulley forests between ridges on poor coral and limestone soil, associated with Pometia at an altitude of up to 150 m.

Banka, R., & Baker, W. (2004). A Monograph of the Genus Rhopaloblaste (Arecaceae). Kew Bulletin, 59(1), 47-60. doi:10.2307/4111073

Type

Solomon Islands, Guadalcanal, Honiara, March 1964, Moore et al. 9310 (BSIP 4085) (holotype BH; isotypes BSIP, K!).

Morphology General Habit

Moderately robust solitary mid-canopy palm bearing up to 10 - 14 leaves in the crown, with a mass of short, stout adventitous roots present at the stem base

Morphology Stem

Stem to 12 m tall or more, 15 - 20 cm diam.; surface grey- brown, becoming light grey distally, with chocolate- brown scales on new internodes, leaf scars prominent

Morphology Leaves

Leaf sheath 60 - 70 cm long, light green with dense indumentum of brownish white scales; crownshaft 60 - 80 cm long, 20 - 25 cm wide; petiole short, 5 - 8 cm long, green, concave on adaxial surface, rounded on the abaxial surface; rachis 3 - 3.5 m long, with dense indumentum of shiny brownish black scales and deciduous white tomentum on the adaxial and abaxial surfaces; leaflets 70 - 76 each side of rachis, borne 3 - 5 cm apart, in one plane, semi-spreading, middle leaflet 64 - 68 x 2.7 - 3.4 cm, linear, tapering acutely and bifid at the apex, adaxial surface green, stiff, papery with prominent veins, abaxial surface pale green, with twisted, reddish brown ramenta present along abaxial surface of the mid-veins, dense black membranous scales as on rachis on adaxial surface of mid-veins near base of the pinnae, less dense on the abaxial surface

Morphology Reproductive morphology Inflorescences

Inflorescence 30 - 45 cm long, branched to 2 orders, primary branches 15 - 16, up to 40 cm long, basal pair of primary branches strongly recurved; prophyll 35 - 40 x 5 - 6 cm, brown-silky- tomentose; peduncle 6 - 8 cm long, 6 - 7 cm diam., orange-green basally and then green distally; rachillae slender, 30 - 35 cm long, 3.2 - 3.9 mm diam., dull green

Morphology Reproductive morphology Flowers

Pistillate flower 5 - 5.8 mm long, 4 - 4.3 mm diam. at anthesis; sepals 3 - 3.3 x 5 - 5.5 mm; petals 3.5 - 4 x 2.5 - 3 mm, broadly elliptic; staminodes 4, lobes 0.9 - 1 x 0.8 - 0.9 mm, united at the base; gynoecium 3.5 - 4 mm long, 2.8 - 3.5 mm diam., ovoid Staminate flower slightly assymmetric, 6 - 7 mm long, 4 - 4.5 mm in diam. at anthesis; sepals 2 - 2.5 x 3 - 3.5 mm, rounded; petals 5 - 6 x 3 - 3.5 mm, broadly elliptic; stamens 4.5 - 5 mm long, filaments 2 - 2.5 mm long, connate at the base, anthers 3.6 - 3.8 mm long, 0.9 - 1 mm diam.; pistillode ovoid-conical, 2.5 - 3.2 mm long, 1 - 1.2 mm in wide at the base

Morphology Reproductive morphology Fruits

Fruit 25 - 26 mm long, 20 - 23 mm diam., globose, yellowish green to orange when immature, with cupule of persistent perianth 4.5 - 5 mm long

Morphology Reproductive morphology Seeds

Seed 17 - 21 mm long, 18 - 20 mm diam., globose, brownish, with conspicuous impression over hilum; testa brown.

Distribution

Restricted to the Solomon Islands from Choiseul and St Isabel to Guadalcanal.

Ecology

In gulley forests between ridges on poor coral and limestone soil, associated with Pometia at an altitude of up to 150 m.

Vernacular

Dai'e, Fai Dai (Kwara'ae), Auki (Angariru).

Conservation

Data deficient. While the relatively wide distribution of R. elegans in the Solomon Islands suggests that the category "Least Concern" may be appropriate, we know too little about the distribution of this species and the threats that it might face to make an assessment at this stage.

Note

R. elegans is easily distinguished from other species by its large globose fruits, slender fruit- bearing rachillae and inflorescences branched to two orders.

IUCN Red List of Threatened Species https://www.iucnredlist.org/species/38682/10137819

Conservation

DD - data deficient