24 July 2010

Senna sp. ‘Pallinup River’ – Undescribed S. artemisioides subsp.

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Senna sp. ‘Pallinup River’ – Undescribed S. artemisioides subsp.

Senna sp. ‘Pallinup River’ has been lumped in with the variable and general grouping called Senna artemisioides subsp. x coriacea, but they have distinctive boat shaped leaflets that are longer and thinner, with plants ranging from the Nullarbor to Albany and extending up to 300 km (185 miles) inland. The still variable Senna artemisioides subsp. x coriacea is recognised as a hybrid/s and also occurs in the Esperance region, but locally is rarely encountered.

Like many Senna species, this one has a liking for limestone and in this instance favouring a non-calcareous overlay of fine sand/clay. It also has a higher moisture requirement than most other WA sennas and is commonly found around roadside culverts and granite outcrops, where rainfall run-off is channeled and soils remain moist for longer periods. They also do particularly well after bushfires or where the soil has been disturbed, although their longevity is dependent on the growth of taller shrubs that will eventually dominate sunlight and moisture availability, consequently they are often short lived in these situations.

Senna sp. ‘Pallinup River’ grows to a metre (3’) in height and can be reasonably bushy with pleasant pale green divided foliage (usually in two pairs). The bright golden yellow flowers (little over 1 cm or ½” diameter) are quite prolific and providing the environment retains moisture, will flower over several months by producing additional blossom on any new growth. The most intense flowering period is from August to November, but depending on local rainfall, flowers can also be produced at other times.