Australian Tropical Rainforest Plants - Online edition

Helicteres isora L.

Herb (herbaceous or woody, under 1 m tall)
Shrub (woody or herbaceous, 1-6 m tall)
Click/tap on images to enlarge
Flower [not vouchered]. CC-BY J.L. Dowe
Flowers. © A. Ford & F. Goulter
Leaves and fruit. © CSIRO
Scale bar 10mm. © CSIRO
Cotyledon stage, epigeal germination. © CSIRO
10th leaf stage. © CSIRO

Linnaeus, C. von (1753) Species Plantarum 2: 963. Type: Habitat in Malabaria, Jamaica.

Common name

East Indian Screw Tree; Isora, Red; Red Isora; Spiral Bush


Usually flowers and fruits as a shrub about 2-5 m tall.


Twigs, petioles and both the upper and lower surfaces of the leaf blade clothed in stellate hairs. Stipules filiform, hairy, about 5-7 mm long. Leaf blades about 6.5-19 x 3-11 cm, margins irregularly crenate. Twig bark strong and fibrous when stripped.


Flowers produced along the stems. Pedicels about 5-10 mm long. Calyx about 20 mm long, the lobes about 2-3 mm long. Outer surface of the calyx tube clothed in stellate hairs. Petals variable, two wide and three narrower. Petals clawed, about 30-35 mm long, a gland or scale present near the junction of the claw and petal limb. Stamens ten, staminodes five, alternating with each pair of stamens. Anther locules borne one above the other. Gynophore curved, about 40-45 mm long.


Fruit about 3-5 cm long, hairy, densely clothed in stalked, stellate or branched hairs, carpels 5, spirally twisted. Pedicel about 4 cm long. Seed about 1.5-2 x 1.5 mm, brown with a finely rugose surface. Cotyledons folded and rolled around the radicle.


Cotyledons wider than long, about 4 x 5 mm, apex truncate or notched, petioles about 1.5 mm long. Lower surface of the cotyledons and the petioles clothed in stellate hairs. First leaves +/- orbicular, about 7-8 x 6 mm, margins +/- crenate with 5-7 teeth on each side, petioles about 1.5 mm long. The upper surface of the leaf blades glabrous, the lower surface clothed in stellate hairs. At the tenth leaf stage: all parts of the seedling clothed in stellate hairs. Leaf blade broadly obovate, base cordate, margin irregularly crenate with about 15-30 teeth on each side, venation palmate with 3-7 veins radiating from the base. Stipules linear, about 4 mm long, clothed in stellate hairs. Taproot thickened, carrot-like (Daucus carota). Seed germination time 11 to 77 days.

Distribution and Ecology

Occurs in NT, CYP and the Gulf Region of NEQ near the Northern Territory border. Altitudinal range from near sea level to 200 m. Grows as an understory plant in open eucalypt forest, vine thickets, monsoon forest and the edges of gallery forest. Also occurs in Asia and Malesia.

Natural History & Notes

It is easily grown and withstands dry periods.

This species may have medicinal properties. ( /herbage/A12946.htm)

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