Alectryon tomentosus

woolly rambutan


Alectryon tomentosus

(F.Muell.) Radlk. 1879

pronounced: a-LECT-tree-on toh-men-TOH-suss

(Sapindaceae — the lychee family)

synonym — Nephelium tomentosum

F.Muell. 1858

pronounced: neh-FEE-lee-um toh-men-TOH-sum

common names: woolly rambutan, hairy bird's eye

native 4Alectryon from the Greek αλεκτρυων (alectryon), a cock, referring to the cockscomb appearance of a ridge on the fruit. It was the name of a Greek youth who stood guard outside Aphrodite’s door when she was visited in the night by Ares, the god of war. Alectryon fell asleep, and Helios, the sun god, was able to enter the room and discover the lovers. As a punishment, the youth was turned into a cock, who daily announces the arrival of the sun.

Tomentosus is from the Latin tomentum, a stuffing for cushions, of wool, hair, feather, straw, etc., and –osus, meaning ‘full of’; in botanical Latin: fully covered with hair. In the synonym, Nephelium is from the Greek νεφελη (nephelé), a cloud.

Although most authorities use “tomentosus” as the specific, The Plant List of Kew Gardens gives it as “tomentosum”. Although I normally follow Kew slavishly in matters of taxonomy, I am not doing so in this case: the generic is masculine in gender, and the specific, according to the rules of nomenclature, should agree with the generic, and have the masculine ending. Kew's nomenclature is not consistently treated in this genus..

This is a small tree, up to a DBH of about 30 cm. In its natural habitat it can reach up to 15 m tall, but is often smaller. It was first described by von Mueller near the Brisbane River, and is found in all types of rainforest. The trees pictured are in the remnant rainforest at the end of Mandalay Avenue in Nelly Bay, and are the only specimens of the species I have observed on Magnetic Island. The species is endemic to Australia, occurring from Cape York down the east coast as far as the Hunter River, at altitudes up to about 950 m. The tree is also cultivated in other countries with tropical or subtropical climates.

The trunk is grey and smooth. The leaves are paripinnate, with the leaflets increasing in size as they are further out on the axis. There are 4 - 8 leaflets, the margins usually regularly dentate, the upper surface either smooth or finely hairy, and the lower surface usually hairier; the petiole is 10 - 30 mm long, and the petiolules 1 - 2 mm.

The flowers are small and inconspicuous, and usually creamy pink to reddish. Those found locally so far, however, have flowers that are cream in colour.

The fruit is a hairy capsule, 1 - 3 lobed, opening to reveal a red aril and shiny black seeds. This is one of the few rainforest trees that fruits heavily in the winter.

The seeds are carried by birds, but propagation generally takes place quite close to the parent tree, which is often surrounded quite densely by young trees. This is a prolific dry rainforest pioneer, very hardy, and able to withstand dry periods. It is often found sprouting in Brisbane suburban gardens.

dangerous 2The fleshy aril is quite pleasing to the taste, although there isn’t much of it; but the seeds are cyanide collectors, and toxic, especially if chewed. Great caution should be exercised if you are tempted to taste these fruits.

The wood is pinkish, close-grained and tough and may be suitable for tool handles. The tree is generally too small to be of much commercial value.

Along with other Alectryon species, this is a host plant for the caterpillars of:
       • Erysichton lineata, the Hairy Line Blue butterfly,
       • Nacaduba berenice, the Six Line Blue,
       • Prosotas felderi, Felder’s Line Blue,
       • Sahulana scintillata, the Glistening Blue,
       • Prosotas dubiosa, the Small Purple Line Blue, and
       • Candalides spp., the Pencilled Blues. They feed on juvenile foliage and flower buds.

The tree is also host to the Leptocoris tagalicus bug.

Green Catbirds (Ailuroedus crassirostris) feed on the fruits.

Photographed at Nelly Bay 2013, 2017
Page last updated 7th December 2019