Australian Tropical Rainforest Plants - Online edition

Cycas silvestris K.D.Hill

Shrub (woody or herbaceous, 1-6 m tall)
Click/tap on images to enlarge
Female plant in fruit. © B. Gray
Fruit. © G. Sankowsky
Female, megasporophylls. © G. Sankowsky
Habit. © G. Sankowsky
Scale bar 10mm. © CSIRO
Cotyledon and 1st leaf stage, hypogeal germination. © CSIRO

Hill, K.D. (1992) Telopea 5(1): 181. Type: Queensland:Cook District: c. 0.75 km NW of Bolt Head, 14 July 1990, J.Clarkson 8813 & J. Neldner: holo: NSW; iso: BRI, MBA.

Common name



Stem can reach a height of 8-9 m under favourable conditions but is more commonly encountered in the 3-4 m range.


Compound leaves about 170 cm long. About 80-95 leaflets on each side of the compound leaf rhachis, each leaflet blade about 17-35 x 1-1.5 cm. Leaflets +/- decurrent on the compound leaf rhachis. Midrib conspicuously raised on the upper surface. Compound leaf petiole spiny.


Male 'flowers' produced in a cone about 20-30 cm long(?) Female 'flowers' (megasporophylls) about 25-30 cm long, each producing 2-10 ovules on the margins of the upper half. Fertile section about 30-40 x 15-22 mm, narrowly triangular, margin dentate, apical spine about 8-15 mm long.


Individual infructescences about 28 cm long. Seeds ovoid, about 30-35 x 25-30 mm, sarcotesta about 1.5-2 mm thick. Testa or endocarp with a small indentation at one end.


First pair of leaves compound, each leaf with a few linear leaflets. Petiole below the first pair of leaflets armed with spines about 5 mm long. Taproot swollen, carrot-like (Daucus carota). At the tenth leaf stage: leaflet blade about 10 mm wide with a conspicuous raised midrib on the upper surface but no other obvious venation. Spines present at least on the apical half of the petiole. Taproot thick and swollen, carrot-like. Coralloid roots present and sections of these roots reveal congregations of blue-green algae. Seed germination time 49 days.

Distribution and Ecology

Endemic to CYP, known only from collections made in the Olive River area of Cape York Peninsula. Altitudinal range quite small, from near sea level to about 50 m. Grows in vine thickets and similar types of vegetation on old sandhills.

Natural History & Notes

This plant has considerable horticultural potential for low care gardens.

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