Botany

Overview of the Drosera Genus of Australian Natives



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Representatives of the Drosera genus can be found on every continent bar Antarctica. All belong to the sundew (Droseraceae) family and about half of the 100 plus species are endemic to Australia. They appear in a diverse range of environments from the swamps of South America, the snow-covered alps of New Zealand and the rainforests of Borneo.

The leaves are covered in tentacles. All species obtain their nourishment by attracting insects to the sparkling sticky substance on the tentacles on the leaves. The tentacles close around the insect, in some cases the leaves do too, and the soft body of the insect is dissolved by digestive enzymes.

In general, Drosera species can be divided into:
*  Tropical species – These can be grown in sphagnum moss. Place in pots in a tray of water in a shady position. They need high humidity and the temperature needs to be kept above 15oC.
*  Subtropical species – Many of these are easy to grow. Use a soil mix of peat and sand, 3 parts to 2, and keep the soil damp. They can be positioned in sun or part shade. In colder areas they can be placed in a greenhouse or on a sunny windowsill.
*  Temperate species – Use a similar soil mix as for subtropical species. Place the pot in a tray of water. Place in full sun in temperate areas or part-shade in warmer climes. The plants will normally be dormant over winter.
*  Tuberous species – Again use a 3 parts peat to 2 parts sand mix. In their native Western Australia (most tuberous species come from WA), the plants are dormant over the hot, dry summer. Keep the pots dry and out of direct sunlight then, as winter approaches, water by placing in a tray of water as the plant comes out of its dormancy and new growth appears.

Tropical species
Drosera adelae or lance-leafed sundew is native to the coast of northern Queensland. It is an herbaceous perennial with lance-shaped, narrow leaves with sparse tentacles. The very beautiful flowers are tiny in size and appear in spring and summer.

Found in northern Australia and New Guinea is Drosera petiolaris or woolly sundew. It has a rosette of leaves and is found in very wet soil which dries out over winter. Under cultivation, winter dormancy will not occur if the plant is kept damp. The leaves have bright red tentacles round the edges. White or dark pink flowers develop in spring and summer.

Subtropical species
Drosera pygmaea or pygmy sundew is found in damp sandy soils in New Zealand and south-eastern Australia. The leaves are round and on short stalks. Tiny white flowers appear in spring. This species is ideal for home cultivation.

A subtropical species found in Western Australia is Drosera hamiltonii or rosy sundew. It occurs in swampy soils and has fleshy green, spatula-shaped leaves which are covered in red tentacles. The large, light purple flowers appear in spring and summer.

Temperate species
Drosera arcturii comes for the mountains of south-eastern Australia and New Zealand. It has narrow, strappy leaves which have a purplish brown tint. The flowers are small, white and star-shaped.

Drosera spatulate is native to eastern Australia, New Zealand and New Guinea. It grows in wetlands and has green to red leaves depending on the light conditions. The leaves are spoon-shaped and covered in red tentacles. Up to 15 small, white to pink flowers are borne on 1 or 2 erect, leafless stalks.

Tuberous species
One of the climbing sundews is Drosera macrantha, also known as the bridal rainbow, or climbing sundew. It is endemic to Western Australia and has small, cup-shaped leaves with spiky red tentacles along the climbing stem. White to pink flowers appear in spring.

One of the larger species is Drosera giganta or giant sundew. It is found in bogs, creek beds and sandy soils in Western Australia. Numerous branches issue from a central stem. The leaves are shield-shaped and a mustard yellow. The flowers are small and white.

The sundews are a fascinating genus but really just another of Australia’s unique wildflowers.

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