19 October 2008

Commersonia fraseri

Looking almost like last minute spring snow fall dusting the branches (if we had such a thing in temperate Australia) - and flowering right now, September-October, is a native shrub in the Sterculiaceae family, Commersonia fraseri. If we are lucky it may even continue with the odd extra flower until January. I have noticed a long flowering season is likely if we have a wet spring and summer. When that is the case the shrubs often flower again in March. If you are travelling around the coast the shrubs are most noticeable at the moment where a bridge crosses a creek. There you will see a mass of white flowers in the gully alongside.

On the Central Coast Commersonia fraseri grows into a large shrub or small tree, 2 to 3 m tall. It is often one of the first shrubs to regenerate where clearing has taken place, particularly along river banks, in sheltered gullies, or along roadsides where it can get a little more moisture than average. It is also grows from East Gippsland, Victoria right into south eastern Queensland, wherever there is wet schlerophyll forest or creek-side rainforest.

The flowers are white and sweetly scented, reminiscent of honey. They are placed along the top of the horizontal branches in loose clusters, giving a massed bloom effect to the whole shrub.

Each individual flower is only 5-7mm in diameter but they are massed in groups, each 3-5cm across. Each flower has five sepals, triangular in shape, five long, skinny, ribbon-like petals that are generally longer than the sepals and another five staminoides; (each three lobed with one vertical and two horizontal lobes), narrow and ribbon-like, as long as the petals but more erect.

This arrangement gives a fluffy look to the flowers.

The fruit is 15 to 25 mm across and covered with soft bristles 5 to 10mm long. They open into five cells, each with two angular, egg-shaped, dull black seeds.

The new leaf branchlets are slender, fawn and covered in a soft down, becoming hairless with age.

The leaves are alternate, simple and variable in shape. Juvenile leaves are broad, jagged and softly hairy, feeling a little like fine, soft velvet, with a fine point at the tip. They are dull on both sides, dark green above, white hairy beneath. Main lateral veins are clearly visible on both sides of the leaf. There are usually five veins, each ending in a larger tooth on mature leaves.

As they age they are more broadly lance shaped to heart shaped, with irregular teeth, two to three teeth per centimeter, often lobed or with a larger tooth at the end of each major lateral vein.

The leaves on these shrubs are always well eaten. Even when very new it is possible to find holes where something has had dinner. (See underside of new leaf above). Whether that is moth or butterfly larva or something else I have not yet been able to determine. This can give quite a straggly, moth eaten appearance to these shrubs

Commersonia fraseri can be grown from cuttings, but with their strong suckering habit care would need to be taken with placement. They would make a good background plant or could be used for screening purposes or utilized as a cover plant when attempting to establish a rainforest. They are very fast growing and quite hardy, accepting at least half shade and tolerant of frost. The sheer number of flowers and the beautiful perfume certainly makes them deserving of a place, if space can be found.

They evidently support wildlife so perhaps space could be found for that reason alone.

A complete list of butterflies and larva supported by the Sterculiaceae family.


My favourite book for attempting to name the plants on my 10 hectares of rainforest and dry schlerophyll forest is Native Plants of the Sydney District An Identification Guide by Alan Fairley and Philip Moore, published by Kangaroo Press and readily available. It is a great book because almost every plant has a photograph, particularly of the flowers, which is what I always notice first in any plant.
Rainforest Trees of Mainland South-eastern Australia by AG Floyd,published by Terania Rainforest Publishing Lismore, Australia. Also a great book with a wealth of information but no photographs

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