Species profile—Cycas desolata

Classification

Plantae (plants) → Equisetopsida (land plants) → Cycadaceae → Cycas desolata

Photo of Cycas desolata () - Forster, P.,Queensland Herbarium, DES (Licence: CC BY NC)

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Species details

Kingdom: Plantae (plants)
Class: Equisetopsida (land plants)
Family: Cycadaceae
Scientific name: Cycas desolata P.I.Forst.
WildNet taxon ID: 6326
Nature Conservation Act 1992 (NCA) status: Vulnerable
Conservation significant: Yes
Confidential: Yes
Endemicity: Native
Pest status: Nil
Short Notes: Gymnosperm, three sheets plus carpological, status annotated by author
Description: Cycas desolata is a cycad with a trunk growing to 4m tall, occasionally to 8m. The leaves are blue when young, aging to dull green, 75-120cm long. Strongly keeled in cross-section (V-shaped), with 90-136 leaflets the opposing pairs inserted at 30-50 degrees to the rhachis (central leaf stalk). The, petiole (basal leaf stalk) is 10-23cm long and spineless (lacking pinnacanths). The leaflets mid-way along the stalk are 18-21cm long, 3.5-5mm wide, narrowing to 2.5-4mm at the base, spaced 1-5mm apart, and are flat in cross-section or margins slightly recurved. The cataphylls (reduced leaf-like structures enclosing the whole of a developing shoot) are linear, 3-4.5cm long, and sharply pointed.
The male cones are narrowly ovoid (egg-shaped), orange to brown in colour and 24-40cm long by 8-9.5cm in diameter. The scales arranged around the male cone are 2.8-3.8cm long and 5-13mm wide, with a 3-4mm spine at the tip. The female sporophylls (megasporophylls) are 13-24cm long and bear 2-6 ovules. The apical lobe (expanded part at the apex) is ovate, 28-32mm long, 20-25mm wide and obscurely toothed with an apical spine 5-15mm long. The seeds are 35-39mm long and 32-35mm wide.
The species is distinguished from the related C. cairnsiana and C. cupida by the pale-blue new foliage with relatively few leaflets per leaf, the spine-free leaf petioles, the relatively long and spiny cataphylls, and the shorter apical spine on the megasporophyll lobe. (Forster 1995; Hill 1998)
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Habitat: Cycas desolata occurs on flat terrain and low rocky outcrops in sparse open ironbark (Eucalyptus spp.) woodland, on stony shallow soils. (Hill 1998)
Reproduction: Male cones shed pollen and female sporophylls are receptive in November. Pollination is effected by small beetles in an obligate mutualism.
Notes: Contributors: Ailsa Holland, Paul Forster, Mellisa Mayhew 17/06/2009
References: Forster, P.I. (1995). Cycas desolata (Cycadaceae), a new species from north Queensland. Austrobaileya 4(3): 345.
Herbrecs (2008). Cycas desolata, in BriMapper version 2.12. Queensland Herbarium. Accessed 29/09/2008.
Hill, K. (1996). A taxonomic revision of the genus Cycas (Cycadaceae) in Australia. Telopea 7(1): 1-64.
Hill, K.D. in McCarthy, P.M. (Ed) (1998). Flora of Australia 48: 613.
Jones, D.L. (2002). Cycads of the World, Ancient Plants in Today's Landscape. edn 2. New Holland Publishers, Australia.
Profile author: Ailsa Holland (17/06/2009)