Thursday, April 25, 2013

Darling Downs Grasslands

I recently found a really excellent blog article on the grasslands of the Darling Downs, written by a visitor from Victoria,  John Morgan, who leads the Plant Ecology Lab at the Department of Botany at La Trobe University.He speaks of "C3" and "C4" grasses.  See article below for an explanation of these terms.
My only criticism of the article is that I wish he had learned to spell the name of our fair city. (It features as "Tawoomba").
(It's an interesting perception, too, that he thinks our local botanists are "more like cowboys". One hopes this is a reference to their sensible headgear, not to their style of botany!)
See it at:

Slender Bamboo Grass, Austrostipa verticillata, a C3 grass

Grasses for All Seasons
C3 or C4?
The first grasses, like most other plants, used a type of photosynthesis known as “C3". Many of them still do. These grasses are known as winter grasses, and tend to be found in the southern half of Australia. Their seeds germinate in autumn, and the plants do most of their growing in autumn and spring. C3 grasses stay green over winter and are at their best in partially shaded areas. They flower in spring, and seeds mature in early summer, after which the plants brown off and remain dormant through the hot period. Then they return to their active growth phase in autumn.
River Tussock Poa labillardieri, a C3 grass

Summer  grasses were a later arrival on the evolutionary scene. They came with an innovation in photosynthesis, known as “C4", which makes particularly efficient use of atmospheric carbon dioxide. They are thought to have evolved around 30 million years ago at a time when the world temperature dropped dramatically, and the available CO2 halved. The C4 process allows these plants to photosynthesise while keeping the pores in their leaves closed. This saves water, but works best in hot conditions. Their ability to make efficient use of water means that they make more green leaf out of a given amount of water than C3 grasses do.

Queensland Blue Grass (Silky Blue Grass) Dichanthium sericeum, a C4 grass.
C4 grasses evolved in the tropics, and their descendants are still happiest in the northern parts of Australia, where the rains come in summer. Their  seeds germinate best in hot, wet weather. Typically fast-growing plants, they are more active in summer than winter, and they prefer to grow in full sun.
Once established, (as indicated by their first flowering), they are very drought hardy. After growing and flowering actively throughout the summer, they have a little rest period in winter, and may brown off.
C4 grasses also tend to be well-adapted to poorer soil..

 Barb wire grass Cymbopogon refractus, a C4 grass
We live in the part of Australia where C3 and C4 grasses overlap. Those of us who like to grow grasses in our gardens have plenty of local native species of both types to choose from. This is a great convenience for gardening, because a mixture allows us to have actively growing green grass for most of the year.
It also means that we can have the beauty of their flowers and seedheads – and the bird-attracting seeds – for a longer period than we would if we only grew one kind or the other.

Choosing Local Grasses for Local Gardens
Here is a shortlist of the more popular perennial grasses for garden use:

C3 Grasses
Austrodanthonia bipartita (Rytidosperma bipartitum) LEAFY WALLABY GRASS
Austrodanthonia racemosa (Rytidosperma racemosum) CLUSTERED WALLABY GRASS
Austrodanthonia tenuior (Rytidosperma tenuius) PURPLISH WALLABY GRASS
Austrostipa aristiglumis PLUMP SPEARGRASS (PLAINS GRASS)
Austrostipa ramosissima STOUT BAMBOO GRASS
Austrostipa verticillata SLENDER BAMBOO GRASS
Elymus scaber WHEAT GRASS
Microlaena stipoides WEEPING RICE-GRASS
Notodanthonia longifolia (Rytidosperma longifolium) LONG-LEAF WALLABY GRASS
Poa labillardieri RIVER TUSSOCK
Poa sieberiana SNOW GRASS

C4 Grasses
Bothriochloa bladhii FOREST BLUEGRASS
Bothriochloa erianthoides (Sorghum erianthoides) SATIN TOP
Capillipedium spicigerum SCENTED TOP
Chloris truncata WINDMILL GRASS
Chloris ventricosa TALL WINDMILL GRASS
Cymbopogon refractus BARB WIRE GRASS
Dichanthium sericium QUEENSLAND BLUE GRASS
Dichanthium queenslandicum KING BLUEGRASS  NB: listed as VULNERABLE
Panicum decompositum NATIVE MILLET
Panicum queenslandicum,  YABILA GRASS (Umbrella grass)
Sarga leiocladum (Sorghum leiocladum) NATIVE SORGHUM
Themeda avenacea NATIVE OAT GRASS
Themeda triandra  (Themeda australis) KANGAROO GRASS

Kangaroo Grass Themeda Triandra

Friday, April 19, 2013

Soft Water Vine

Cayratia eurynema
Climbing is one of plants’ knackiest inventions.
Leaves are their little solar power stations, and the more of them it can place in sunny positions, the better the plant grows. You know the story, I’m sure. Using solar energy, leaves convert carbon (from carbon dioxide in the air), and hydrogen (from water, which is made of hydrogen and oxygen) into carbohydrates. They release lots of lovely oxygen in the process, and use the carbohydrates for body-building and the energy to do it.

In a crowded environment with a dense canopy, new little plants may never be able reach enough light. Many wither on the forest floor.
Rainforests are called “vine forests” for a good reason, though. All sorts of quite unrelated plants have evolved into vines. Climbing has given them the ability to acquire height quickly. Because they use other plants for support, they don’t have to spend time and energy building their own trunks. Therefore they can compete effectively for a share of the sunlight, at a much earlier age than a seedling tree, germinated at the same time, could ever do.
They use a lot of different techniques. Some just scramble, poking lots of little branchlets among the foliage of other plants to support themselves. Some use thorns to hang on. Some twine their stems around any support they can find - I have even seen a blood vine twining up a strong strand of the web of a golden orb spider.
Some have developed specialised twining organs, called tendrils.
All those methods depend the climber finding suitable bits of vegetation to grab.

Just a few plants have bypassed all that, and climb straight up the trunks of giant trees. Most of them do it with clinging roots, produced along their stems.

Cayratias, like a very few other members of the grape family, have a very specialised way of achieving it. They have adhesive discs on the ends of their tendrils.

Some of their overseas relatives like Boston ivy Parthenocissus tricuspidata (which is really a kind of grape, not an ivy at all) and Virginia creeper (P. quinquefolia) have found a special place in gardens because of this ability. They can climb on masonry, so are used to ornament brick walls and buildings.
Our local soft water vine can probably be used in the same way. Plants with clinging tendrils have the advantage over root-climbers like ivy, in that they restrict themselves to the wall’s surface, rather than sending questing roots into mortar and tiny cracks, to grow and break the wall apart.
The soft water vine can also be grown on trellises and pergolas.
It is an attractive foliage plant, one of the few local examples of plants with "pedately compound" leaves. Note how the stem first divides into three, then two of these divisions divide into two. This distinctive style of leaf makes it easy to identify in its native rainforest habitat.
 Soft water vine has large bunches of tiny white flowers, and bird-attracting little black “grapes”.
It is frost tender, and can tolerate heavy shade (which means it can also be used indoors, as a pot plant).

Wednesday, April 10, 2013

White Bollygum

Neolitsea dealbata
I took this photo last week in Goomburra National Park.

You can see that this tree has fruits in the bird-attracting colours of red and black. They are ripening progressively, which , besides making the tree highly attractive, will provide food for an extended period. White-headed pigeons were there in a crowd.
We can find the plant growing naturally along Great Dividing Range, mostly on the eastern side, but also in damper, more sheltered western sites within a few kilometres of the Range. It differs from its rainforest cousin Neolitsea australe in having larger leaves, smaller and more colourful fruits (about 1cm) and a bit of hairiness in the shoots, leaf-stems, and the veins on the backs of the leaves. Mature leaves have white backs, and are aromatic when crushed. Note the brown, hairy leaf-stem (petiole).

Extremely good value in a garden, it is a fast-growing small tree. It makes an excellent screen with foliage extending to the ground, or can be trimmed up to make a small shade tree. Drought hardier than other Neolitseas, it is a suitable candidate for waterwise gardens in Toowoomba and nearby red soil areas. Like all dry rainforest plants, however, it grows faster if watered and mulched in its first few years of life.
It would prefer a frost-free corner of the garden.
New flushes of leaves are very ornamental. A soft shade of pinkish brown, they hang limply all over the plant.

This young plant is growing in a local garden. Photographed last November, its new flush of leaves were just hardening off.

White bollygum is a member of the laurel family, whose members are all host plants for blue triangle butterflies.