Australian Tropical Rainforest Plants - Online edition

Gyrocarpus americanus Jacq.

Shrub (woody or herbaceous, 1-6 m tall)
Click/tap on images to enlarge
Flowers and juvenile leavs. © CSIRO
Male flowers. © CSIRO
Flowers. © Mick Godwin
Leaves and fruit. © G. Sankowsky
Scale bar 10mm. © CSIRO
10th leaf stage. © CSIRO
Cotyledon stage, epigeal germination. © CSIRO
10th leaf stage. © CSIRO
Trunk. © G. Sankowsky

Jacquin, N.J. von (1763) Selectarum Stirpium Americanarum Historia : 282. Type: Colombia, Cartagena, N. Jacquin. Holo: BM. Fide Kubitzki (1969).

Common name

Coolamon Tree; Gyro Damson; Helicopter Tree; Shitwood; Twirly Whirly Tree


Deciduous; leafless for quite long periods between June and October. Bark rather shiny brown. Blaze odour noticeable but difficult to describe.


Width of the leaf blades approximating or exceeding the length. Leaf blades about 7-24 x 4-21 cm. Petioles about 4-19.5 cm long. Hairs normally visible with a lens on the upper surface.


Most flowers male with only occasional hermaphrodite flowers. Male flowers: Flowers very small, about 2-3 mm diam. Tepals triangular, small, about 0.75-1 mm long. Perianth tube about 1 mm long. Anther filaments very hairy, about 1-1.25 mm long, anthers about 1 mm long. Hermaphrodite flowers: Style + stigma about 2 mm long. Style sigmoid. Stigma capitate.


Fruits usually 2-winged, each wing +/- spathulate, about 50-70 x 9-14 mm. Cotyledons much folded. Endosperm scanty.


Cotyledons papilionate, about 20-35 x 40-50 mm, hairy on the upper surface, 3-5 veined. At the tenth leaf stage: leaf blade triangular or cordate, usually with one large lobe or tooth each side of the midrib, hairy on the upper surface, densely hairy on the undersurface; petiole hairy; taproot and stem swollen, carrot-like (Daucus carota). Seed germination time 3 to 232 days.

Distribution and Ecology

Occurs in WA, NT, CYP, NEQ, CEQ and southwards to coastal central Queensland. Altitudinal range from near sea level to 900 m. Grows in monsoon forest, dry scrub and open forest. Pantropic, also occurs in Africa, Asia, the Pacific and Central America.

Natural History & Notes

Three subspecies occur in the region, see Flora of Australia Vol. 2.

This species may have medicinal properties. This plant used medicinally by Aborigines. Cribb (1981).

Gyrocarpus americanus Jacq. subsp. americanus, Botanische Jahbucher 89: 183(1969). Gyrocarpus americanus subsp. sphenopterus (R.Br.) Kubitzki, Botanische Jahrbucher 89 : 185(1969), Type: Queensland, Carpenraria region, R. Brown 4468. Holo: BM. Iso: E, NY, P. Fide Kubitzki (1969). Gyrocarpus sphenopterus R.Br., Prodromus Florae Novae Hollandiae : 405(1810), Type: Northern Territory, Arnhem Bay, R.Brown 4468. Holo: Bm. Iso: E, NY. Gyrocarpus acuminatus Meisn., Prodromus 15(1): 248(1864), Type: Ad Port Denison, Novae Holl. (Ferd. Mueller!). Holo: G-DC. Iso: NY. Fide Kubitzki (1969). Gyrocarpus jacquinii Gaertn., De Fructibus et Seminibus Plantarum 2: 92(1791), Type: E collectione sem. Banksiana. Gyrocarpus americanus subsp. pachyphyllus Kubitzki, Botanische Jahrbucher 89 : 185(1969), Type: Australien. W.-Australien. Broome: HOCHREUTINER 2831 (G; L, Typus ..). Gyrocarpus rugosus R.Br., Prodromus Florae Novae Hollandiae : 405(1810), Type: Northern Territory, Arnhem Bay, R.Brown 4468. Holo: Bm. Iso: E, NY. Fide Kubitzki (1969). Gyrocarpus asiaticus Willd., Species Plantarum 4(2) : 982(1806), Type: Habitat in India orientali.
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