Ptychosperma macarthurii

Common name

Macarthur palm

Description

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 leafleaf:
in palms -- the leaf blade (which is usually divided into leaflets or leaf segments), the petiole (or leaf stalk) and the sheath (which forms the attachment of the leaf to the stem)
scar rings. Leaves: Pinnate, reduplicatereduplicate:
Most palm leaflets or leaf segments are obviously folded. If the folds create an upside-down V-shape, with the margins lower than the midrib (so that rain might "run off the roof"), the folding is reduplicate.
, 1-2 m long, with a slightly arching rachisrachis:
an extension of the petiole through the blade of a pinnate leaf to which leaflets are attached
holding drooping, regularly arranged leaflets in a single plane. The crown shaftcrown shaft:
a cylinder of clasping leaf sheaths toward the apex of the stem, found in some pinnate-leaved palms (e.g., <em>Wodyetia bifurcata</em>)
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 ramentaramenta:
irregularly shaped, thin scales, sometimes found along the abaxial midrib of a leaflet
on the underside. Leaflet tips are truncated and jagged (praemorse). Flowers and fruits: Inflorescenceinflorescence:
the reproductive structure of a flowering plant, including palms, consisting of flowers and associated bracts
is pendulous, to 60 cm long and with yellowish branches. White male and female flowers are borne on the same inflorescenceinflorescence:
the reproductive structure of a flowering plant, including palms, consisting of flowers and associated bracts
. The ovoid, red fruits are 1-1.5 cm long and have remnants of the stigma at the apex.

Diagnostic features

Slender, clustering, gray stemmed palms with pinnatepinnate:
like a feather; palms with pinnate leaves usually have compound leaflets attached to a rachis, although a pinnate leaf may be entire with pinnate veins (e.g., <em>Chamaedorea metallica</em>)
leaves, a short crown shaftcrown shaft:
a cylinder of clasping leaf sheaths toward the apex of the stem, found in some pinnate-leaved palms (e.g., <em>Wodyetia bifurcata</em>)
with a waxy white coating, and praemorsepraemorse:
with a jagged edge or like a fish tail
leaflets that are are green on both sides.

May be confused with

Ptychosperma elegans, but it is a taller, solitary palm with ascending rather than drooping leaflets.

Distribution

Native to southern New Guinea and northern Australia

Additional comments

This palm is native to swampy areas, but is sometimes cultivated, including in Hawaii.

Scientific name

Ptychosperma macarthurii (Wendl.) Nichols.

Family

Arecaceae/Palmae

Synonyms

Actinophloeus macarthurii (H. Wendland. ex J. G. Veitch) O. Beccari. ex Wigman

Kentia macarthurii H. Wendland. ex J. G. Veitch