The Soybean (Glycine max) is known to most of us. Originally from China, it is now grown worldwide and is one of the world's most important sources of protein and oil.

Well, Australia has its very own native soybeans (Glycine species). In fact, most species in the soybean genus are Australians, and a number of them are common in the Grassy Box Woodlands. They are hardy species that are often found in remnants, both ungrazed and lightly grazed. Look for them in late spring and summer when their clusters of mauve-pink to purple flowers adorn the grass tufts or dead branches they twine up.

We don't suggest that people rush out and start shelling native soybeans for the pot, but scientists in both Australia and the US certainly see them as an important genetic resource. Some native species show high resistance to the serious disease soybean rust (Phakopsora pachyrhizi), and could be used to develop a resistant commercial cultivar. The pollination biology of native species is being studied to help improve production of hybrid seed in soybean crops. Deep-rooted perennial legumes like native soybeans have potential for ameliorating salinity problems, and a cultivar of one species (Glycine latifolia) has already been released as a commercial pasture species for the black soils of the Darling Downs in south-east Queensland.

Being legumes, all soybeans have important relationships with Rhizobium bacteria, which live in root-nodules and allow the plant to fix nitrogen from the air. Research into the rhizobia of soybeans, including native Australian strains, is being undertaken in the US, and may be important in helping with revegetation efforts.

For all these studies, scientists need to collect native soy beans from many different natural populations, to screen for differences in disease resistance etc. That's another reason why saving Grassy Box Woodland remnants, with their precious cargo of native plants and animals, is so important.

Growing native soybeans

Native Glycine species should be easy to grow and reintroduce into Grassy Box Woodland remnants. Collect seeds in summer when the pods begin to split. The seeds have hard coats like wattles and other legumes, and will benefit from hot-water treatment - put some seeds in ajar and cover with just-boiling water. Leave to cool, then examine the seeds - some will have swelled to double their size, others will be unchanged. Sow the swollen ones in ordinary potting mix. Germination will be rapid.

How to recognise native soybeans

The two most common native soybean species found in the Grassy Box Woodlands of New South Wales are Glycine tabacina and G. clandestina. Both have long, trailing or twining stems, with leaves made up of three leaflets, as in clovers. The leaflets are often roundish in very young plants, but become long (0.7 -8cm) and narrow (2-10 mm) in mature plants. The plants have small, mauve to purple pea-shaped flowers. They produce slender pods like beans, each to about 5 cm long and 4 mm wide. These two species are best distinguished by the length of the stalks on their leaflets. In G. clandestina. all three stalks in a leaf are about the same length, while in G. tabacina the middle leaflet has a distinctly longer stalk than the two lateral ones. The leaves of G. tabacina can be difficult to distinguish from another twining woodland pea, Slender Tick Trefoil (Desmodium vari{ms). However, that species has very different pods (with distinctive constrictions around each seed) and white to pink flowers.

Other native soybean species that might be found in the Grassy Box Woodlands include G. tomentella (Woolly Glycine), with soft goldem-brown hairs on the leaves, G. latifolia, with broad, almost round, leaflets, and G. canescens (Silky Glycine), with very slender, silky-hairy leaflets.

References

Button, U. (1988) Major gene resistance to Phakopsora paehyrhizi in Glycine caneseens, a wild relative of soybean. Theo, Appl. Gene/. 75, 923-928.

Doyle, J.J., Doyle, JA & Brown, A.H.D. (1999) Origins, colonization, and lineage recombination in a widespread perennial soybean polyploid complex. Proe. No/I. Acad. Sei. USA 96,10741-5.

Kenworthy, W.J., Brown, A.H.D. & Thibou, G.A. (1989) Variation in flowering response to photoeriod in perennial Glycine species. Crop Science 29, 687-82.

Lolicato, S. J. and Rogers, M.E. (1997) Adaptation of pasture legumes to acid, shallow soils in Central Victoria. Aus/. J. Expa Ag,ic 37, 779-91.