Archontophoenix: Difference between revisions

Overview:[edit]

Archontophoenix H. Wendland & O. Drude is a genus of single-stemmed, pinnate-leaved, monoecious, Arecoid palms endemic to eastern Australia. The genus was established in 1875 by Hermann Wendland and Oscar Drude in the journal Linnaea. Though no type species was designated at the time of publication, the accepted lectotype is A. alexandrae (F. Mueller) H. Wendland & Drude (=Ptychosperma alexandrae F. Mueller) which was described in the same publication. A number of other names have been applied to the genus; for example Seaforthia, Ptychosperma, Loroma and Jessenia.

The genus is rather undifferentiated and the species do not display a great degree of variation. The main features of the genus include: solitary habit; tall erect trunk; leaf bases forming an elongate crownshaft; leaves paripinnate; pinnae linear-acute with a prominent midrib raised on both surfaces; inflorescence infrafoliar at maturity, protandrous, branched to three or four orders; two bracts which fully enclose the inflorescence in bud, the prophyll attached at the base of the peduncle, fully enclosing the peduncular bract which is attached slightly above the attachment of the prophyll; bracts are completely deciduous immediately prior to floral maturity; flowers unisexual and borne in triads throughout most of the rachillae, staminate flowers only in the distal portion; peduncle short; rachis elongate, angled proximally, becoming terete distally; rachillae zig-zagged throughout or distally; staminate flowers asymmetrical in bud; petals thin, angled, valvate, opening widely at anthesis; stamens 9-34; anthers dorsifixed near the middle; pistillode about as long as stamens; pistillate flowers smaller than the staminate, globose; stigma trifid; staminodes three; gynoecium unilocular, uniovulate; fruit one-seeded, conic-ovoid to elliptical, red at maturity; stigmatic remains apical or nearly so; mesocarp with thin to thick fibres; endocarp thin, brittle to crustaceous, non-operculate; hilum elongate; endosperm ruminate; embryo basal; germination adjacent-ligular; eophyll bifid.

Variation between the species is primarily expressed in the following characteristics: degree of enlargement of the base of the trunk; colour of the crownshaft - from shades of green to red/purple; degree of lateral twist in the leaf the pinnae in near-horizontal to vertical orientation; whether silver/grey scales or ramenta are present or absent on the lower surface of the pinnae; size and degree of branching of the inflorescence; colour of the flowers white/cream to lilac; number of stamens - 9-34; whether the filament is desexed or not; size of the fruit - 8-26 mm long; texture of the epicarp - smooth or pebbled; position of the stigmatic remains apical or eccentric; thickness, type and degree of branching of the fibres within the mesocarp; the degree of adherence of the raphe fibres to the seed; and the degree to which the mesocarpic fibres are embedded in the endocarp. Distribution of the genus in along the eastern coast of Australia, from Durras Mountain, New South Wales [35&deg 10'S] to Cape York, Queensland [10° 40'S], in coastal and near coastal lowlands and ranges, from sea-level to 1200 m altitude. Lowland and moderate altitude populations are continuous for many kilometres where conditions permit (e.g. A. alexandrae, A. cunninghamiana and A. tuckeri, whilst other species have small populations which are isolated and remote from others (e.g. A. myolensis and A. maxima).

Main habitats include rainforest, wet sclerophyll, gallery forest, moist vineforest and swampforest; and occasionally in seasonally dry forests such as deciduous or semi-evergreen vineforests. Soil types are varied, derived from granite, basalt, metamorphics, siliceous sand and schists.

The Species:[edit]

The taxonomic history of A. cunninghamiana began in 1857 when W. Hooker described Seaforthia elegans in Botanical Magazine. There was some confusion in regards to the true identity of the taxon which he intended to describe; some of the accompanying illustrations depicted what we now know as Ptychosperma elegans as well as A. cunninghamiana. The following year, Hermann Wendland clarified the situation with his description of Ptychosperma cunninghamiana in Botanische Zeitung. Subsequently Wendland and Drude renamed it Archontophoenix cunninghamiana in 1875 in Linnaea when they created Archontophoenix as a new genus. A. alexandrae was first described in 1866 as Ptychosperma alexandrae by Ferdinand von Mueller in Fragmenta Phytographiae Australiae.

The early history of this species is not as complex as A. cunninghamiana; Wendland and Drude transferred it to Archontophoenix in Linnaea in 1875. Two subspecies of A. alexandrae have been named, A. alexandrae var. schizanthera by Wendland & Drude in the same publication, and A. alexandrae var. beatricea ( the latter originally as P. beatricea by von Mueller in 1882), both of which now appear to be unnecessary considering the overall variability of that species.

(by John Dowe from Palms & Cycads No. 39, Apr-Jun 1993)