The genus Ptychosperma has two species occuring naturally in Australia, both confined to tropical Queensland. The species under consideration in this paper is P. macarthurii (H Wendl. c x Veitch) H. Wendl ex Hook.f. in subgenus Actinophloeus section Caespitosa .(1 )
This highly attractive palm has a fairly limited distribution, from the southern MacIllwraith Ranges in north-eastern Cape York Peninsula to Cape York and various Torres Strait Islands, north to the region around the Fly River delta in almost lowlands east of the Great Divide, however the present author has observed a rather small colony of it along the lower Wenlock River in north-western Cape York Peninsular.(2 )
P. macarthurii is a small palm of moist rainforests and broad-leaved riverain gallery forests and favours light to moderate shade, a rich, moist loamy or sandy soil and a high humidity. In places where a large tree has fallen, letting in more light than is usual, this plant responds with great vigor. The leaf crowns become larger and the stems attain greater diameters.
Figure 1. P. macarthurii in Kuching, Borneo.
It should be mentioned here that this species is polymorphic; that is there are several forms of it and the Australian ones are considerably different to that cultivated form. The plants encountered in cultivation are all apparently progeny from the collections of Sir William Macarthurs gardener, J. Reedy, who obtained his material from the Katau or Binatauri Rwer in the Gulf of Papua region of New Guinea. Seeds were sent to the then Botanic Garden at Buitenzorg in Java, now Bogor. It is probable that all cultivated material has come from Bogor originally without further collections of wild seed of a different form.
The commonly cultivated P. macarthurii is considerably more vigorous than the Australian plants growing in the wild; it has numerous stems which attain greater diameters and broader pinnae. In the Iron Range area for instance, this species is mostly solitary trunked with few to many small basal shoots, which may or may not mature. Forms with very slender stems add pinnae are common and are so delicate and distinct that at first one cannot understand the true nature of them.
Environmental factors are naturally very important. In heavy shade the plants can mature (flower) when only 2m tall and with stems only 1-3c.m. in diameter while those experiencing stronger light are larger. Stems can attain heights of up to 15m. but are commonly 5-8m. The adaptability of this species under varying light conditions is such that a specimen can be made to suit any site under cultivation. A plant may form a delicate and tiny specimen, eventually flowering in a 5-8 gallon container under rather dark conditions, while a large and vigorous plant can be grown in the ground in a brightly light site.
This species is also tolerant of a wide range of soil conditions. Along the tidal reaches of the lower Claudie River here at Iron Range, it can be seen growing amongst the mangroves and Nypa fruticans vegetation where it receives regular salty or brackish inundations and full sun.
Flowering is seasonal and begins in October or November but can be earlier and later depending on conditions and plant health. The brilliant red fruit begin to ripen in January mostly, appearing until at least the present month, April.
In the Lockhart River region the Palm is called 'Achar' by the Aboriginal people and was formerly a food, the tender "cabbage" being eaten.(3 )
This species is fairly hardy and should succeed under cultivation in any reasonable cfimate of the sort already proved suitable for the Papuan form of the same. The juveniles grow moderately at first but after forming their 8th - lOth leaf increase in vigor and should attain maturity in 2-3 years.
References: 1. Essig, F.B. A Revision of the Genus Ptychosperma Labill (Arecaceae ), Allertonia Vol. 1, No. 7, 1978. 2. Tucker, R. Notes on the Palms of Northwestern Cape York Peninsula, Principes Vol 24, No. 3, 1980. 3. Ethnobotany notes from Lockhart River (MS)   Contributed by: Robert Tucker (Text - from Palms & Cycads No. 2, May 1984) Mike Gray (Figure 1)
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