Saturday, February 3, 2018

Something special, in Rainy Weather.

Tar Vine Boerhavia dominii

Some of you will be familiar with this delightful little plant.

I photographed the one below near Wyreema,

and the one below this was at McEwan State Forest near Pittsworth. As you can see, the leaves vary a bit from place to place.

The plant itself is not showy enough to ever become popular as a garden ornamental, but is pretty, all the same. The tiny flowers are exquisite. As a romantically-inclined farm child from the Darling Downs, I was sure they would be fairy favourites.

A friend from Pittsworth sent me these photos yesterday, showing the amazing transformation of the seeds after rain. She says the little blobs which have developed to encase the seeds are “slimy”.

Aren’t they beautiful? Like little pearls! If you click on the photos, you can get a good look at the details.

On the second rainy day, the seeds are falling off, and collecting under the plant, looking "like frogspawn".

The reason for it all is that the seeds contain mucilage, which swells when wet, encasing the seed in a little damp ball to improve its chances of staying wet long enough for the newly germinated seeds to have a good chance of growing. Now would be a very good time to move some of those seeds into a bare dry patch that needs a bit of ground cover, and tuck them under a light cover of damp soil, being careful to preserve their mucilage coating. They can cope with a very tough, sunny site that gets very dry.

The mucilage has another function as well. It is designed to stick to the fur of passing mammals.This technique has helped the plant to spread itself about over much of Australia.

ADDENDUM: Since I published this blog, a correspondent has told me several other things about this plant.
The secret of its survival in hard, dry conditions is its persistent  taproot. This root is edible, and is still collected for this purpose by people living a traditional lifestyle in Central Australia. (If you want to try it, please be cautious. It may need to be cooked first). The leaves of the closely related B. diffusa are often used as a green vegetable in many parts of India.
Apparently it is unpopular with farmers, and can actually reduce the value of a farm because it is a difficult "weed" to kill by any means including poison, and tends to tangle in a plough. Pastoralists, however, regard it as a good, palatable pasture plant. Horses are said to get fat (and lazy) on it.

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