Short Cuts

Short Cuts in this issue:

Smoke Treatment for Baeckea behrii

If You Must Eat Nardoo Sporocarps....

Banksias, Sand and Superphosphate Don't Mix!

Underground Orchid Found in Blue Mountains

The Jar on the Window Sill

Smoke Treatment for Baeckea behrii

I love the delicate drifts of white baeckea that flower on the mallee sandhills during spring. In the past I had tried to grow Baeckea behrii from seed, but I had only been able to grow plants from cuttings. As this Baeckea is a good sandhill-stabilizer, I wanted to promote it for direct-seeding. But I needed to find a way to get it to germinate freely. I decided to try smoke treatment of the seed.

My method is one that anyone can follow; no special equipment is needed.

1. I placed the seed (mixed with a little sand) on a tin lid which I put on a bed of dry grass and eucalypt leaves. All were placed within an old cast iron pot.

2. I set fire to the grass and leaves. When the fire was burning well, I put the lid on the pot. At first I left the lid slightly angled. but I closed it completely as the fire went out.

3. I left the seeds in the smoky pot for about an hour and then I sprinkled them over some seed raising mix in an alfalfa sprout punnet (I use these punnets for very fine seed because their lids fit very snugly and so retain moisture well). Within three weeks dozens of Baeckea behrii seedlings had emerged.

If You Must Eat Nardoo Sporocarps, Prepare them in the Aboriginal Way!

Robert O'Hara Burke, William John Wills, John King and Charles Gray were the first Europeans to cross the Australian interior from south to north. They started from Melbourne in 1861 and reached the Gulf of Carpentaria, but Burke, Wills and Gray all died on the return journey. King was cared for by Aborigines and survived, though crippled. The three deaths have long been somewhat of a mystery, because the explorers state that they had access to plenty of food but it was considered by Wills to lack "nutriment", but now there is an alternative, and highly plausible, explanation. This explanation was provided by John Earle, a biochemist at Sydney's Royal Alexandra Hospital for Children and Barry McCleary, an agricultural scientist. In the scientific journal "Nature" (volume 368, pages 683-684, 1994), they provide evidence that Burke, Wills and Gray died of beriberi, caused by a deficiency of vitamin B1 (thiamine). They base this conclusion on the description of the symptoms recorded by Wills, combined with knowledge of the chemical makeup of freshwater mussels and Nardoo sporocarps that formed part of their diet. The symptoms of acute beriberi are hypothermia, weakening of the pulse and severe muscle wasting leading to an inability to move.

With their rations of flour and salted beef running low, the Burke and Wills party began to eat the freshwater mussel Velesunio ambiguus. The first symptoms of beriberi (near-paralysed legs and breathlessness) started soon thereafter. This is attributed by Earle and McCleary to the enzyme thiaminase that is present in these mussels. It breaks down the vitamin thiamine, so inducing deficiency in the eater. But worse was to come, because the explorers began to supplement their diet with the seedlike sporocarps of the Nardoo fern, which they had seen the local aborigines eating. (Nardoo is the common name of ferns of the genus Marsilea, of which eight species are indigenous to Australia. These ferns grow in shallow water throughout inland Australia. M.drummondii was probably the main species used. Sporocarps are hard, woody structures about 0.5-1 cm long that are produced on stalks that arise from the rhizome. They bear sori, which are the structures in which spores are produced.)

The explorers ground the sporocarps dry, then cooked the flour in much the same way that wheat and barley are ground and cooked. This method of preparation contrasted with that used by the Aborigines, who ground them with water to make a thin paste. As Earle and McCleary explain, Nardoo sporocarps also contain large amounts of the enzyme thiaminase. Mixing the flour with water stops the enzyme's action and also dilutes the other chemicals that are needed for the enzyme to destroy thiamine. In their preparation method, the Aborigines did not allow the watery paste to come into contact with bark or leaf utensils. Had they used bark or leaf, amino acids from them could have activated the thiaminase. The explorers may have lived had they followed the Aboriginal preparation methods.

One wonders how many Aborigines died while the preparation method was being worked out.

From the February 1996 issue of the "SGAP Journal", the newsletter of the South Australian Region of SGAP.

Banksias, Sand and Superphosphate Don't Mix!

Phosphorus is a chemical element which is essential for the growth and reproduction of plants. It is contained in structural materials such as cell walls, metabolic chemicals such as ATP and RNA, and the genetic blueprint molecule, DNA. Soils contain many kinds of phosphorus chemicals which may be of mineral, vegetable or animal origin, but for the purpose here they can be regarded as either readily available or sparingly available to plants. The quantity of sparingly available phosphorus in the soil is usually very much larger than the quantity of readily available phosphorus.

Mast of Australia's soils and rocks contain relatively low amounts of readily available phosphorus. The main exceptions to this are loamy alluvial soils and soils derived from basalt. These soils generally support rich vegetation such as rainforest or dense Eucalypt forests (except where water availability is severely limited). The most phosphorus deficient soils are those from ancient, strongly weathered soils developed 'in situ' from sedimentary rocks such as sandstone or from coarse alluviums. Deep sands and podsolics (sand over clay subsoils) are typical phosphorus deficient soils, and heaths and xeromorphic shrublands are typical vegetation types of low phosphorus soils.

Within various plant communities there are many adaptations used to obtain and retain phosphorus, and these are most developed in the heath vegetation, since efficient use of the extremely limited soil phosphorus is critical to their survival. For example, they often have enormous root systems (even in moist areas). To retain phosphorus, many heath plants have tough, unpalatable leaves to resist attack by pests and grazing animals.

Some members of the Proteaceae from the heath and shrublands, including many Banksia spp. and Grevillea spp. possess an unusual adaptation known as proteoid (pro-tee-oid) roots. Proteoid roots are highly active in phosphorus uptake and may be able to utilise some of the relatively large quantity of sparingly available phosphorus in our poorer soils. Unfortunately, while these plants are beautifully adapted to poor soils, they may suffer from phosphorus toxicity if fertilised with soluble phosphorus fertilisers.

All fertilisers have an N:P:K ratio on the packet, such as 23:5:18 or 10:5:0. Any fertiliser where the middle number is not zero can cause phosphorus toxicity in sensitive species. Safe fertilisers include things such as urea (43:0:0), ammonium sulphate (21:0:0), lime (0:0:0) and muriate of potash (0:0:30?). Most "general" fertilisers contain phosphorus.

However, the good news is that most phosphorus fertilisers such as superphosphate are either quickly utilised by plants or converted to sparingly available forms. This is especially true in light soils (ie. coarse grained) which have a low phosphorus buffer capacity. This means that they have little resistance to changes in the quantity of readily available phosphorus in them. Therefore, plants in light soils can go quickly into a toxic state and may die, but the soil will quickly (a few years) recover. After 2-3 years the readily available phosphorus would usually be almost depleted. Heavy soils and acid soils usually have a high phosphorus buffer capacity and are less likely to go toxic, but are also slower to recover if toxicity does occur.

Ways to speed up the removal of readily available phosphorus from soil with a toxicity problem include adding a soluble form of iron such as ferrous (iron) nitrate or making the soil more acid by adding ammonium sulphate. Treatment with iron and calcium nitrate will have a slight acidifying effect, as well as adding soluble iron, and so should be especially good. Iron sulphate should also be quite an effective treatment. Fairly high rates of these chemicals are usually required (see the labels for directions).

If toxicity occurs on heavy soils, especially those that are already acid, the most realistic solution may be to grow rainforest rather than heath plants.

Rainforest plants, including members of !he Proteaceae, such as Silky Oaks (Grevillea robusta), Wheel-of-fire (Stenocarpus sinuatus), Beefwoods (Grevillea striata) and the Ivory Curl (Buckinghamia celsissima), are not sensitive to phosphorus fertilisers. With lots of phosphorus floating around, they grow like mad, and then the main things to worry about are water and nitrogen. But that's a very different story ......

From the Newsletter of the NSW Far North Coast Group of SGAP; April 1988.

Underground Orchid Found in Blue Mountains

The life cycle of R.slateri is enacted entirely underground except for a short time in spring when the purplish flower head protrudes into the surface litter but, even then, the head may be a few millimetres below the surface. The plant has no chlorophyll and lives in a symbiotic relationship with a soil fungus yet to be identified.

More is known about the only other Rhizanthella species. R.gardneri, from Western Australia, was first seen in 1979 and has since been found to associate with a fungus which, in turn, has only been identified on Melaleuca uncinata. Pollination is performed by small flies, wasps and termites. R.gardneri also spends its entire life underground.

Based on material in the Newsletter of SGAP's Indigenous Orchid Study Group; April 1996.

The Jar on the Window Sill

You have bought a single herbaceous plant - Scaevola, Goodenia, Myoporum, Brachyscome, Rhodanthe, Helichrysum, Derwentia - and, seeing it bloom, would be delighted if it could be multiplied to fill a bed, adorn a border and add that splash of colour to a particular spot.

Scaevola ramosissima is a scrambling plant which is common in open forests along Australia's east coast. Select the thumbnail image or plant name for a higher resolution image (31k).

But how to propagate easily without fuss, a glass house and daily care? Despair not!!! You only need a glass jar and you can strike many species from the genera mentioned above.

To proceed....

• Sever leafy stems up to 30cm long with a clean cut, strip lower leaves to about 7 or 8 cm from the base, the section that is to be immersed in that depth of water in your jar.

• Change water about once per week.

• Choose a spot that is well lit, free from droughts and, for extra warmth, receives morning sun, although this is not essential. If the area is exposed to night flouro lighting, quicker rooting will result.

• Roots formed tend to be soft and brittle so take care when potting out.

• Hold potted plants in semi-shade for 3-4 weeks before planting out or until growth indicates that they are well rooted.

• Different species may be put in the same jar.

• Any plants that are succulent, herbaceous or soft-tissued are worth trialling by this method. For example Kennedia prostrata, which I tried on impulse, struck readily.

• I have not used hormones either in the water or for pre-soaking cuttings, nor have I tried foliar feeding with liquid fertilisers but I imagine that they could be helpful.

From the March 1996 issue of "Calgaroo", the newsletter of the Society's Parramatta and Hills District Group.

The Society for Growing Australian Plants