Actinorhytis H.Wendl. & Drude, Linnaea 39: 184 (1875)Protologue

Primary tabs

http://media.e-taxonomy.eu/palmae/photos/palm_tc_2778_7.jpg

Distribution

Map uses TDWG level 3 distributions (http://www.nhm.ac.uk/hosted_sites/tdwg/geogrphy.html)

A single species, Actinorhytis calapparia, native to New Guinea and the Solomon Islands, now widespread as an ornamental or ceremonial plant in Southeast Asia. (J. Dransfield & N. Uhl & C. Asmussen & W.J. Baker & M. Harley & C. Lewis, Genera Palmarum. The evolution and classification of palms. 2008)

Discussion

Diagnosis

Biology And Ecology

Etymology

Uses

Description

  • Tall, solitary, unarmed, pleonanthic, monoecious tree palms. Stem erect, bare, conspicuously marked with leaf scars, with a large mass of roots at the base. Leaves pinnate, arching, neatly abscising; sheaths tubular, forming a long, slender, well-defined crownshaft, bearing scattered caducous scales, the mouth with a short ligule; petiole very short in mature individuals (long in juveniles), adaxially channelled or flattened, abaxially rounded, densely caducously tomentose; rachis conspicuously down-curved toward the tip; leaflets very numerous, close, regularly arranged, single-fold, acute, acuminate or briefly bifid, the margins thickened, adaxially glabrous, abaxially with minute dot-like scales and conspicuous ramenta along the midrib, transverse veinlets obscure. Inflorescences infrafoliar, erect in bud, becoming horizontal or pendulous, branching to 3 orders proximally, to 1 order distally, protandrous; peduncle short, winged at the very base, grossly swollen just above the base in the centre, caducously tomentose; prophyll inserted near the base of the peduncle, tubular, beaked, 2-keeled, entirely enclosing the inflorescence in bud, sparsely scaly, splitting abaxially, deciduous; peduncular bract, inserted just above the prophyll, similar to the prophyll but scarcely 2-winged, deciduous; subsequent bracts low, triangular, inconspicuous; rachis longer than the peduncle, ± elliptic in cross-section, bearing relatively few, large, spirally arranged first-order branches, with conspicuous, bare, proximal portions; rachillae rather stiff, elongate, bearing spirally arranged triads in the proximal 1/2 to 2/3, and paired or solitary staminate flowers distally, or rarely, bearing only staminate flowers; rachilla bracts low, rounded, quite conspicuous, tending to form very shallow pits; floral bracteoles sepal-like. Staminate flowers asymmetrical in bud; sepals 3, distinct, imbricate, ± triangular-tipped, keeled; petals 3, distinct, ± ovate, valvate, ± 2–3 times as long as the sepals; stamens 24–33 or more, exserted at anthesis, filaments slender, elongate, inflexed at the tip, anthers medifixed, narrow oblong, ± versatile, latrorse; pistillode columnar, ± as long as the stamens in bud, shorter when stamens exserted. Pollen ellipsoidal asymmetric, occasionally elongate; aperture a distal sulcus; ectexine tectate, perforate-rugulate, aperture margin similar or slightly finer; infratectum columellate; longest axis 33–50 µm [1/1]. Pistillate flowers globular, at anthesis much larger than the staminate; sepals 3, distinct, imbricate, rounded; petals 3, ±twice as long as the sepals, distinct, broadly imbricate with conspicuous, triangular, valvate tips; staminodes 3, narrow triangular, flattened; gynoecium ovoid to obovoid, unilocular, uniovulate, stigmas 3, large, fleshy, recurved, ovule laterally attached near the apex of the locule, hemianatropous. Fruit very large, ovoid, ± beaked, green turning red at maturity, perianth whorls persistent, stigmatic remains apical; epicarp smooth, mesocarp with thin flesh and abundant anastomosing fibres adhering to the endocarp, endocarp closely adhering to the seed, thin, ± bony. Seed globose, with lateral, longitudinal hilum, endosperm deeply ruminate, with a central, irregular hollow; embryo basal. Germination adjacent-ligular; eophyll bifid. Cytology not studied. (J. Dransfield & N. Uhl & C. Asmussen & W.J. Baker & M. Harley & C. Lewis, Genera Palmarum. The evolution and classification of palms. 2008)

Anatomy

Fossil record

  • A fossil seed from the Upper Eocene of Hungary with a ruminate endosperm has been described as Actinorhytis eocaenica (Rásky 1956), but it lacks the central hollow and distinctive radiating ruminations of the modern genus. This fossil seems likely to be a palm, but its equation with the modern genus Actinorhytis is highly suspect. Asymmetric monosulcate pollen with a distinctive irregularly columellate infratectum, Palmaepollenites sp., from the Middle Eocene of Central Java (Nanggulan Formation) is compared with pollen of Actinorhytis and with pollen of Cyphosperma, Cyphophoenix and Moratia (= Cyphokentia) (Harley and Morley 1995). (J. Dransfield & N. Uhl & C. Asmussen & W.J. Baker & M. Harley & C. Lewis, Genera Palmarum. The evolution and classification of palms. 2008)

Relationships

Taxonomic accounts

Bibliography

A. J. Dransfield & N. Uhl & C. Asmussen & W.J. Baker & M. Harley & C. Lewis, Genera Palmarum. The evolution and classification of palms. 2008
B. World Checklist of Arecaceae