Thursday, November 26, 2009

Now Flowering in Ravensbourne

Here are three plants whose fruits we notice more often than their flowers. A walk along the lower track at Ravensbourne National Park takes them all in.

Blue ginger Alpinea caerulea

There are a lot of buds on the plants beside the track, so they’ll make a pretty show for some time yet.
Though not as showy as the flowers of exotic gingers, they are pretty little things. They will be followed by showy electric-blue fruits around May next year.

(See entry May 2009 for photo of some of the last crop of fruit.)

Palm Lilies Cordyline petiolaris

The long-lasting bright red fruits are more often seen than these more ephemeral flowers. These beauties are right beside the main walking track, this week.

(See post July 7, for more on this plant)

Black Bean Castanospermum australe
This is one of the dominant trees of the dry rainforest in Ravensbourne National Park. The flowers are everywhere this year, so we can expect a great crop of the giant chestnut-coloured seeds about next Easter. The trees can flower while still quite young, with the flowers sprouting from old wood. Gardeners shouldn’t get too enthusiastic about pruning these plants, as they could accidentally remove future crops of flowers.
On older trees, the flowers tend to be hidden within the canopy. Our attention is often drawn to them by the clamour of nectar-eating birds.
Grown in the open, black beans trees typically become well-shaped specimens, with a dense canopy of shiny, dark-green leaves. (See the tree on the right, in this photo).

They are ideal for gardens which have room for a medium-sized tree, and make an excellent background plant for large gardens.
I noticed recently that the nursery in the Ikea shop in Brisbane was selling “magic beans”. These were pots with newly sprouted black bean seeds sitting on the soil surface. Very ornamental! Young trees can be used as indoor plants, in well-lit situations, for a number of years.
Black beans are toxic, but not really a family problem, as their seeds are not a size which an innocent toddler could easily swallow. Aborigines, whose diet tended to be low in carbohydrates that could be had from them, did eat these starchy things after a long process involved crushing and soaking them in many changes of water to remove the poisons. Modern bushfood-experimenters have tried it. Reports of the results vary. Some have made themselves very ill. All agree that the taste is so boring it’s not worth the trouble, especially when flour is cheap in the shops, safe, and tastes much the same.
The trees were rigorously exterminated from our area by the early white settlers, who believed them to be also toxic to cattle. Some also claimed that it was the size of the beans rather than the toxins which were the problem. Cattle, they said, swallowed them whole, then were unable to regurgitate them for cud-chewing. Intestinal blockages were the result.
I accepted the idea that black bean trees and cows don’t mix until told otherwise by a dairy farmer who had lived all his eighty years on the same property. This contained many of them dotted about the paddocks as shade for the stock, and cattle ate the seeds freely, he told me. He had never had any problems.
He had recently begun to discourage them, but only because he’d found a market for the seeds in Japan, where they were being used to develop a medicine to combat AIDS.
The dark streaky black bean timber is beautiful, and the trees are plantation-grown in the US as well as here. This is a great tree to grow on a “boutique” timber plantation.
Typical dry rainforest trees, they are drought hardy, and tolerate light frosts. They are quite fast-growing, which is why they dominate parts of Ravensbourne National Park. This park was logged with bulldozers in the thirties, so much of what we see there is still in the relatively early stages of progression to mature rainforest. Slower-growing trees will come later.

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