Craspedia (plant)
| woollyheads billy buttons | |
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| Craspedia canens | |
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| Genus: | Craspedia |
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Craspedia is a genus of flowering plants in the daisy family[2][3] commonly known as billy buttons and woollyheads. They are native to Australia and New Zealand where they grow in a variety of habitats from sea level to the Alps. The genus is found in every state of Australia except the Northern Territory. In New Zealand, Craspedia is found from East Cape on the North Island south to Stewart Island. It also occurs on Campbell Island and the Chatham Islands.[4]
Craspedia are rosette-forming herbs with compound capitula borne on erect, unbranched scapes. The capitula are hemispherical to spherical heads of tiny flowers. Most species are perennial; one species is recorded as an annual (Craspedia haplorrhiza). The leaves have considerable variation in form, ranging in colour from white to green, and are often covered in fine hairs.
Species of Craspedia are found in a wide range of habitats from coastal to alpine and are generally plants of open areas, sometimes ruderal. Observations of some Australian species suggest they re-establish well after fire. In Australia Craspedia are commonly found growing in forest habitat, whereas in New Zealand they are generally excluded from closed Nothofagus forests. Craspedia species may occur in dense, widespread populations in mainland Australia, but generally not in New Zealand or Tasmania.
Most Australian non-alpine species are found in native grasslands and shrublands associated with Eucalyptus forests. Alpine species occur in Tasmania. In New Zealand, species can be found on coastal sand dunes, wetlands, fellfields, and greywacke rock scree.
Craspedia grow in a wide range of soil types, including sands, gravels, clays, and loams, which are derived from different geologies across a broad rainfall gradient. They appear to be intolerant only of very infertile and acidic soils. This is apparent in the absence of Craspedia from parts of western Tasmania which are characterised by soils derived from pre-Cambrian quartzose rock. These sandy, infertle soils are dominated by a wet heath ecosystem known as buttongrass moorland.
There are two centres of diversity in Craspedia, both associated with upland areas. One of these is in the alpine and subalpine zone of Kosciuszko National Park, where seven species are found. The other centre is a larger area on the northwestern South Island, where several species grow.
- Species[1]
Cultivation
Craspedia can be propagated by cutting a rosette from a clump, but generally seed is a more reliable and rapid method. Seeds will sprout in days on germination media. Plants are generally self-fertile. The alpine species need regular water and excellent drainage. All species prefer cool roots; surrounding the plants with rock, gravel, or sand provides better conditions. A plant will start growing as a single rosette, and each rosette generally produces one flower stalk.
See also
A closely related genus is Pycnosorus, also often called billy buttons. The genera can be distinguished by the attachment of individual flower heads to the compound heads; in Pycnosorus they are directly attached, and in Craspedia they arise on small stalks.[5]
References
- ^ a b Flann, C (ed) 2009+ Global Compositae Checklist
- ^ Forster, Johann Georg Adam. 1786. Florulae Insularum Australium Prodromus 58
- ^ Tropicos, Craspedia G. Forst
- ^ Ford, K. A., et al. (2007). Phylogeny and biogeography of Craspedia (Asteraceae: Gnaphalieae) based on ITS, ETS and psbA-trnH sequence data. Taxon 56(3) 783-94.
- ^ Asteraceae Key. New South Wales Flora Online.