Saturday, June 29, 2013

Broad Leafed Ballart

Exocarpos latifolius

The “fruits” on these plants are just beginning to ripen in the Toowoomba area. They are odd little things, not true fruits, but swollen seed-stems (pedicels). However, for the plant’s purposes they serve the same function as fruits. They attract birds which eat the whole thing. The seeds go unharmed through the birds’ digestive tract and are deposited far from the parent tree, each with its little dollop of fertiliser.

Claims are made that the fruits are both edible and palatable. I found this one to be sweet, but so astringent as to be unpleasant. However, I notice that the “Noosa’s Native Plants” website informs us that the fruits must be very ripe and beginning to “wrinkle like a sultana” before they are nice to eat.

The plants are shrubs and small trees, usually to about 3 metres (although they can grow taller). Their broad leaves make them look quite unlike their close relative, the common ballart Exocarpos cupressiformis, with its cypress-like leaves.

Broad leafed ballarts are partially parasitic on the roots of other plants. Although sometimes described as “attacking the roots” of host trees, they are unlikely to be particularly harmful to their hosts. Their dependancy has not been thoroughly studied, but it seems to be the case that they are parasitic only when quite young and have not grown enough leaves to make their own food.
This attractive plant is not known in cultivation, probably because its needs as a young plant, with regard to a host, are poorly understood. It doesn't seem even to be known just which plants it can use, but they may be other shrub and tree species from its semi-evergreen vine thicket habitat. Plants found growing close to the ballarts, in the area where these photos were taken, include Croton insularis, Notelaea microcarpa, Alectryon diversifolius, and Arytera foveolata. It is possible that planting the seeds in a pot with seedlings of those species might succeed.
Ballart seedlings probably also require the correct mycorrhizal fungus to link them with their host plants, so seeds should be planted with a good handful of “mother soil”, gathered from around the roots of the parent ballart. Please let me know, if you have any success!
Near Toowoomba, we most often see this tree on the eastern slopes of the Great Dividing Range, on sandstone soils. However, I have also seen it on the basalt hills in the Kingsthorpe / Gowrie Junction area. Good drainage is probably necessary for its successful cultivation.
Its bark and seeds were traditionally used as contraceptives, and it is one of the many local plants which may prove to be a useful source of drugs - in this case as a possible cure for tuberculosis.
For more on Exocarpos cupressiformis, see Dec 2010

Singles versus Groups

Cupaniopsis parvifolia
Here are some very pretty scrub tuckeroos, demonstrating just how attractive the trees of our local semi-evergreen vine thickets look when grown in full sun

Look at these trees closely, and you will note that the one on the left is a single tree. The “one” on the right is a group of four. They have grown together since infancy, moulding their canopies into a neat single item.
While these trees are naturally occurring, they are demonstrating a neat trick that we can use in gardens. Planting in close groups creates a canopy more quickly than one plant could do alone. The technique is appropriate for all our local dry rainforest plants, whose deep roots don’t compete with each other.
Like so many species of the dry softwood scrubs, scrub tuckeroos are small trees, suitable for suburban gardens with their shady canopies and deep, drought-defying roots.

Friday, June 21, 2013

Our local Banksias

Tree Banksia  Banksia integrifolia
Banksias come into their own in winter, with their nectar-rich flowers feeding birds and insects at a time when other food sources might be hard to find.
Banksia integrifolia is the only banksia species native to our local basalt soils. It is also Australia’s only tree-sized banksia. Despite the often-used common name, "coast banksia", its natural range extends almost as far west as Goondiwindi. It needs very well-drained soil, so is more usually found on sandy than basalt soils, but it grows well in the light red basalt soil at the crest of the Range.

The one native to red soil at Highfields (and shown in the photos in this post) was identified for me at the Qld herbarium as the northern subspecies Banksia integrifolia subsp. compar. However, on another occasion, another herbarium botanist identified trees over the road as Banksia integrifolia subsp. integrifolia, a plant whose range extends as far south as Victoria. I can only think that the truth of the matter is that we live in an area where the two subspecies overlap, and that our locals are intergrades, but I am happy to be corrected!
Our local subspecies, whatever it is, rarely reaches more than 5 metres tall, so is a good choice for garden use. Plants grown from local seed are worth procuring (or grown from seed collected in spring) as they are likely to be hardier to frost and drought than plants sourced from more coastal areas.
Young flowers are green,

maturing to yellow with a slight hint of pink.

Leaves on young plants are quite toothy, but as the plants mature, they become smooth-edged. They grow in whorls of about 3-5, which gives the trees a distinctive look. Even from a distance, it can’t be mistaken for any other tree.

I don’t know the age of this specimen, but doubt if it would be more than ten years old. Older plants get broader, rather than taller.

Like most Banksias, this tree has a lignotuber  - a woody, swollen trunk base, just below ground level. Lignotubers are an adaptation to fire, which may – with some difficulty in the case of this hardy plant - kill off the whole plant above-ground. Below, though, it remains alive and well, and will re-sprout with vigorous multiple stems in the next rain. Trees which don’t suffer this misfortune develop lovely twisted and gnarled old branches. 
The advantage of lignotubers in the garden is that the plants which have them can be pruned hard, to keep them shrub-sized.

Thursday, June 13, 2013

Sword Rush

Lepidosperma laterale

The sword rushes have responded to the wet autumn weather with beautiful heads of flowers and seeds.
This plant is an excellent one for garden use. Though it looks like a water plant, and can tolerate occasional inundation, it prefers to be in dry ground and is even drought hardy. This means it is particularly suitable for garden designs incorporating dry creek beds which might occasionally collect flowing water. It can also be used anywhere in the garden where it gets at least a little shade each day. It can also grow in full shade.
Sword rushes grow into  bright green leafy tussocks half a metre high, with their dark brown seeds atop flat, sword- like stems. The seeds are appreciated by birds.
As the stems harden with age, their edges can be quite sharp,
Sword-rushes are occasionally sold in nurseries as landscaping plants, but local growers might like to collect their own seed in the wild, as plants of inland provenance are likely to be better at coping with drought and frost..
This is a good plant for to grow for basket-making.