06 February 2009

Coastal Hakea - Hakea clavata

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Coastal Hakea - Hakea clavata

A very deceptive common name, as this hakea commonly occurs many kilometres inland, particularly to the north and northeast of Esperance. Hakea clavata is largely restricted to granite outcrops where it grows in shallow soils, where its roots can penetrate rock fractures. This environment is extremely harsh, being exposed to hot and very dry conditions for long periods. However, this harshness represents a habitat that few large shrubs can tolerate, so Hakea clavata can grow with little competition and even provide shelter for small plants beneath.

To survive and prosper in this terribly dry and exposed environment, this hakea has evolved (moisture absorbing) 50-75 mm (2"-3") pencil thick fleshy leaves to help it over the many dry periods typical of low rainfall areas. This moisture saving means Hakea clavata is slow growing and requires many years to fully develop, which is only achievable thanks to large areas of bare rock naturally creating firebreaks to protect these shrubs from periodic bushfires. Some plants on large outcrops and well away from inflammable vegetation, can be of substantial age and grow to over 3 metres (10') in height, plus spread even further.

As this shrub is rarely burnt, the usual hakea genus method of reseeding (by keeping their seed enclosed within a thick woody capsule and only releasing when the plant dies, thus protecting them from bushfires) will not work. So Hakea clavata releases its seed unaided early each summer, thereby giving its prodigy the slim chance of reproduction, providing it is by chance, blown into a vacant crack in the granite and then overlooked by seed eating predators.

The flowers that occur in clusters at the base of leaves, can vary from off-white to a striking deep pinky red, which are visited by both birds and insects. Their main flowering period is from June to October, but they can also flower off and on from January to May particularly after summer rainfall.