Macarthur Palm has stems cespitose 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.
(Smith, A. C. 1979. Flora Vitiensis nova: A new flora of Fiji. National Tropical Botanical Garden.)
(Essig, F.B. 1978. A Revision of the Genus Ptychosperma Labill, Arecaceae.)