Friday, September 23, 2011

Black Bootlace Orchid

Erythrorchis cassythoides (Galeola cassythoides)

It’s flowering time for this fascinating climbing orchid.

It’s a plant with no leaves at all, and is of the kind that is often called a “saprophyte”.

Most of the world’s plants need green stuff for survival. Chlorophyll is what makes leaves green. It’s a substance that is essential for photosynthesis, the process which is the plant equivalent of eating. Photosynthesis uses solar power to combine carbon (taken from carbon dioxide in the air) with hydrogen (from water, which is made of hydrogen and oxygen) to make carbohydrates.

Our bootlace orchid, however, has nothing green about it. Its rather evil-looking black bootlace stems come up from roots which are getting all the food the plant needs by being parasitic on certain soil fungi. The fungi, in turn, are growing on dead plant matter. The term “saprophyte” comes from sapro (decay) and phyte (plant). It means a plant that lives on decaying matter. Nowadays, however, the term is falling out of use, because it is now understood that the alleged saprophytes are really living on the soil fungi, which are themselves living on the decayed matter, Strictly speaking the plants are not saprophytes, but “myco-heterotrophs”!

Bootlace orchids climb up the trunks of their trees with these spongy, water-absorbing roots. For most of the year the plants are quite inconspicuous, but in spring they put out a great show of flowers.

They are closely related to a Mexican climbing orchid, Vanilla planifolia, the source of the vanilla we use for flavouring. You can see the bootlace orchid’s seed pod, which appears in February, does look rather like a vanilla pod.

Bootlace orchids are always found growing on eucalypts which are completely or partly dead - another good reason for not being too “tidy” about clearing away dead trees on our properties.

Saturday, September 10, 2011

The Vet's Grasstree - an update

Xanthorrhoea glauca subsp. glauca
Two years ago, I wrote about this lovely grasstree, one of Toowoomba's most remarkable plants, which grows in the grounds of the veterinary surgery on the corner of West and Herries Streets, in Toowoomba.

I had been told that it had been transplanted there, on a bullock dray, as a large tree - and also that its estimated age was 1500 years.
An interesting story, but quite wrong!
I was delighted to be contacted this week by a member of the family of Mr Ray Lamb, the man who did the transplanting. She had stumbled across my blogsite while researching her own family history.
So I was able to contact him and get the true story - and it turns out that not a single bullock was involved!
For the corrected story, see my article of September 2009
The encouraging thing about it, for those who'd like to grow a tree like this for themselves, is that with good care, you too may be able to produce a tree like this within your own lifetime.
(And if you're in Toowoomba for the Carnival of Flowers, don't miss seeing this lovely plant.)

Thursday, September 8, 2011

Peacehaven Tours

Toowoomba’s Carnival of Flowers is coming up, and the Friends of Peacehaven will be contributing their mite, by running free tours of this new and exciting Botanic Park, each day from
Saturday 17 to Tuesday 20 September, at 2.00pm.
It offers a chance for people to see the first operating Botanic Garden in the Toowoomba Region for many years.

This view, from the “Rainforest Path”, shows the Bunya Mountains in the Distance. Many of the trees planted in Peacehaven are species found in this Darling Downs rainforest.
The garden’s main focus is on plants native to the Downs. Plantings are now 4 to 6 years old, and the small trees are showing impressive growth, demonstrating how attractive our local plants can be and how suitable they would be for garden use. They include trees which attract birds and butterflies, and some bush tucker species.
The Friends of Peacehaven operate a small nursery, which will be opened briefly after each of the tours.
Peacehaven Botanic Park is in Kuhl’s Road Highfields.
To find it, head north out of Toowoomba on the New England Highway. A little over 6k from the northern edge of Toowoomba you reach Highfields’ first set of traffic lights, where you turn left into Cawdor road. Drive 1k, then turn right into Kuhl’s Road. Peacehaven is 300 metres along, on the left.

Arrowhead Violet

Viola betonicifolia
The arrowhead violets are flowering beautifully this week, all ready for Toowoomba's Carnival of Flowers.
The species grows naturally in forests and woodlands, preferring its soil to be a little damp. Its water requirements are not heavy, though. This year-old plant has had no watering since it was planted a year ago. It would be appreciating the mulch which keeps the soil moisture fairly constant.
For a brief period in the 1990s, this perennial native violet species was adopted as the floral symbol of Toowoomba, ousting the better-known “Toowoomba violet” (which is an introduced plant, a large-flowered variant of the European sweet violet Viola odorata).
While my head would prefer to see native plants rather than exotic ones adopted as symbols of cities, my heart is with the introduced plants in this case. Bunches of them were sold by mothers of soldiers lost in the first world war. The money so raised was used to build our iconic “Mothers’ Memorial”. It would be a pity to lose this bit of our heritage.

The spear-leafed violet is native to Toowoomba and along the range. Its deep purple flowers resemble those of the introduced violet, but are slightly redder in hue.

I can understand the wish to use it as our city’s symbol. It was once very common here, and hosted the Australian Fritillary butterfly, a species which is now listed as critically endangered, but may actually be extinct, for lack of the plants on which to rear its babies.
The plant flowers generously in spring. At other times of the year it has the botanically interesting habit producing seeds from small self-pollinating flowers which never open. This has given it an undeserved reputation for “not flowering well” - as the buds seem to come to nothing. It actually flowers beautifully, but only does it in spring.

Thursday, September 1, 2011

Mountain Coolibah

Eucalyptus orgadophila
Just west of Toowoomba, on the blacksoil slopes, is Mountain Coolibah Country. Where you see them growing naturally, you know that the soil pH is approximately neutral, and, compared with soils further west, has a good proportion of phosphorus

Here’s a typical tree. Mountain coolibahs always seem to have a bit of a lean, in the main trunk, and then lesser branches have grown out of the upper side of the leaning trunk. The dark grey fibrous bark persists on the lower trunk, but the beautiful pale branches shed their bark every spring.

The mountain coolibahs are flowering at present. The flowers are not conspicuous, but the air around them is humming with the sound of the European honeybees, gathering the nectar and pollen.

If you live in mountain coolibah country, and want to plant a Eucalypt, you can hardly do better than this tree. It’s very resistant to both frost and drought, koalas love the leaves, and it's a good honey tree. Older trees make good hollows, which are safe havens for gliders and other shy bush creatures.
The hollows are also a popular habitat for our most drought-hardy orchid, the beautiful black orchid of the west, Cymbidium canaliculatum, which survives drought by sending its great mass of roots deep into the hollows of this tree.

As a young thing, mountain coolibah has these pretty blue-green leaves. Note that they are broader than the adult leaves, and have rounded ends with a distinctive notch.

In the original mountain coolibah woodlands, kangaroo grass Themeda triandra, which is now so fashionable for landscape gardening in the cities, was the dominant grass. Overgrazing has caused it to be supplanted by Queensland bluegrass, Dichanthium sericeum. Planting kangaroo grass with this tree in a garden setting would be a nice touch.

It is a fire-resistant tree, and can be part of a “fire ecology”, that type of local vegetation whose health is maintained by regular burning. However when fire is not a regular event in its environment, it shares its root-space with “scrub trees” - those small, shady dry rainforest trees such as scrub wilga Geijera parviflora, and gumby gumby Pittosporum angustifolium, which love to grow on the same soil.