Ptychosperma macarthurii

Ptychosperma (tee-koh-SPEHR-mah) macarthurii (mah-kahr-thur'-ee)
“Apart from the figs, the Oriental Pied Hornbill also readily consumed the red fruits of MacArthur Palms (Ptychosperma macarthurii) growing nearby. Photo by Dr. Leong Tzi Ming & Dr. Vilma D’Rozario. Singapore, Malaysia. 23 rd October 2012
Scientific Classification
Genus: Ptychosperma (tee-koh-SPEHR-mah) Species: macarthurii (mah-kahr-thur'-ee)
Synonyms
None set.
Native Continent
Oceania
Morphology
Habit: Clustering Leaf type: Pinnate
Culture
Survivability index
Common names
Macarthur Palm, Darwin Palm.

Habitat and Distribution

Fiji, New Guinea, Northern Territory, Panamá, Queensland, Society Is., Windward Is.

Huang Chee Thong a.k.a bloodlamb, photographed a male Pink-necked Green Pigeon (Treron vernans), eating the fruit of the MacArthur palm (Ptychosperma macarthurii) by swallowing it whole

Rain Forest Palm. This species occurs in dense rainforests associated with lowland springs near the margins of riverine floodplains. The soils typically comprise deep organic clay loams without humus development. Within the rainforest patches the species will grow in a wide range of light conditions (Duff et al. 1992; Barrow et al. 1993; Liddle et al. 1996).

Description

Stems grow in dense clumps or rarely solitary, up to 7 m tall, only 7 cm in diameter, thus appearing bamboo-like. Leaves are up to 2 m long or more, compound. Leaflets are 23-28 on each side, more or less regularly arranged, with margins nearly parallel or tapered at the tip. Inflorescence are up to 60 cm wide. Male flowers are 6-8 mm long, with 26-40 stamens. Fruit is red, ovoid, 12-16 mm long. Seeds are deeply 3-6-grooved. (Dr.s Kenneth Greby, Yazdy Palia, Satish Pardeshi.) Editing by edric.

Stems: Clustering, each stem with 8-10 leaves, slender, light gray stems to 8 m tall and up to 3-10 cm in diameter, with widely spaced, ridged leaf scar rings. Leaves: Pinnate, reduplicate, 1-2 m long, with a slightly arching rachis holding drooping, regularly arranged leaflets in a single plane. The crown shaft is about 50-60 cm long, somewhat swollen at the base, and light green with a waxy white coating. Leaflets are green above and below, widest toward the middle or wedge-shaped, prominent midribs with brown or tan twisted ramenta on the underside. Leaflet tips are truncated and jagged (praemorse). Flowers and fruits: Inflorescence is pendulous, to 60 cm long and with yellowish branches. White male and female flowers are borne on the same inflorescence. The ovoid, red fruits are 1-1.5 cm long and have remnants of the stigma at the apex. (lucidcentral.org)

Macarthur Palm has stems cespitose (Growing in tufts or clumps) or rarely solitary, to 7 m high, 7 cm in diameter with leaves to 2 m long or more. The pinnae is 23-28 on each side, more or less regularly arranged, obliquely praemorse, with margins nearly parallel or tapered apically. Flowering is seasonal and begins in October or November but can be earlier and later depending on conditions and plant health. Inflorescence is up to 60 cm wide with staminate flowers 6-8 mm long and 26-40 stamens. The brilliant red fruit begin to ripen in January mostly, appearing until April. The fruit is red, ovoid, 12-16 mm long with seeds deeply (3-) 6-grooved with homogeneous endosperm. (Essig, F.B. 1978. A Revision of the Genus Ptychosperma Labill, Arecaceae.

Culture

Light requirement: full sun, partial sun or partial shade, shade tolerant. Soil tolerances: clay; sand; loam; slightly alkaline; acidic; well-drained. Drought tolerance: high. Aerosol salt tolerance: low. Pest resistance: resistant to pests/diseases. (EDIS University of Florida.) Cold Hardiness Zone: 10a+

Comments and Curiosities

Conservation assessment: In the NT, this species is classified as Endangered; Fire and feral animals have been the primary threats impinging on the populations in the 1990s (Liddle et al. 1992ab, 1996, 2001, 2006). There was substantial mortality following wildfires at the Whitewood Road population in 1990 and 1993, and at Black Creek in 1992. In a 1990 survey, Whitewood Road contained 42% of the known adults, however this was reduced to 5% by 2000-2001. Re-survey of Bankers Jungle in 2003 showed significant impacts from grazing with the loss of juvenile and adult plants. Disturbance from feral buffalo, cattle and pigs declined in the 1990s following on from the Brucellosis and Tuberculosis Eradication Campaign, and changes in land use and fencing of four of the eight populations. In the early 1990s, several populations exhibited a polarised size class structure typified by large adult and juvenile plants. In the absence of wildfire and in a period of reduced disturbance by feral animals, sufficient small juvenile plants survived and grew to infill the intermediate classes. In addition to the above, there are increasing threats from: • changed fire regimes due to increased fuel loads from introduced grasses around rainforest margins; • changed land use in the catchment that could lead to a reduction in the water supply to the springs on which the rainforests depend; • changes in surface water quantity and quality; • clearing proposals and any other action that could remove or damage individual rainforest patches that form an interconnected mosaic essential for the flow of genetic material; and • hybridization with introduced Ptychosperma species. (Northern Territory Government)