Thamnochortus insignis (Mast.)

Family: Restionaceae
Common names:
Dekriet, Thatching reed, Albertinia thatching reed

Thamnochortus insignis

Plants of Thamnochortus insignis are tall, grass- or reed-like tussocks with a diameter of 500 mm to 1 metre at the base and a spread of 3 metres or more at the top and up to 2,5 m tall. Male and female plants are separate and very similar when they are not flowering.

Male plant - 5 years oldThamnochortus insignis flowers in summer (January-February) and produces large amounts of seed in autumn (April-May). The plants are at their most ornamental from about 2 months before flowering to a few months after producing seed.

Thamnochortus insignis grows in dense stands in the southern Cape around Albertinia. It can now be found along the roadsides from Port Elizabeth to the Cedarberg, where the seed has been distributed by the trucks carrying the thatching material.

The plants are wind pollinated with the male inflorescences in small tassels swaying in the wind, while the female flowers are at the base of medium sized bracts, which catch the pollen from the air and funnel it towards the small fringed styles of the female flowers. The male flowers produce pollen in such large amounts that female bees come and collect the pollen to use in the beehives and during a still day the droning of the bees around the plant can be heard clearly.

The seed comes in the form of a tiny nutlet inside the old flower, which by this stage has formed two small wings. This helps the wind to carry the seeds away from the plant. The seeds are produced in very large quantities by each female plant, but are not all viable; a large number of nutlets are empty inside. Why the plants expend all this energy to produce sterile seeds is not clear, but is particular to this genus as well as to the genus Elegia.

Growing Thamnochortus insignis

The propagation is from seed. The seed should be treated with smoke, or soaked in a smoke water solution, before sowing. The seed should be sown during early autumn, when the nights are cool, between 10 and 15 degrees Celsius, and the days are still warm, between 20 and 30 degrees Celsius. After about three weeks the seed germinates and after another six to nine weeks can be pricked out.

Thamnochortus insignis occupies a relatively large space and in a large garden it can be a beautiful accent plant. In a fynbos or water-wise garden these plants can form the backbone of the garden, in between the much shorter-lived proteas and ericas.

The plants prefer a deep, slightly acidic sandy soil but adept readily to normal garden conditions as long as the soil is well drained. In garden situations the plants should be planted in a sunny position with good air circulation, do not plant very close to a wall. During the first three months after planting the plants should be watered regularly, once they are growing well they need very little water. When planted in a situation to their liking, the plants will stay very healthy and attract no pests and diseases.

The first culms are small, finely divided and curly looking. The tall, single culms only appear when the seedlings are nearly a year old. When the plants are three years old they are starting to bulk up.

Thatch drying outThamnochortus insignis is the only restio which has a wide commercial use. It is one of quite a few species of restio with tall, straight culms, which in the past have been used for thatching roofs and still are used like this occasionally in rural areas.Stacked sheaves of T.insignis. It is the only species, which is used in such large quantities that it has a commercial value. The plants are long-lived and culms can be harvested every five years. Depending on the weather conditions a well-thatched roof can last about 30 years on the coast and up to 70 years in dry areas like the Karoo.

The Restionaceae family, or restios, occur mainly on the Southern Hemisphere, and are found in South America, Africa, Australia and New Zealand. In Africa there are about 330 species, most of which can be found in the fynbos of the Cape Floristic Region.

For more about thatching and restios see two articles from Veld & Flora:
On restios and roofs by Dr J Rourke (1974)
The thatching reed of Albertinia by H P Linder (1990)


Hanneke Jamieson
Kirstenbosch Botanic Garden
April 2001

To find out if SANBI has seed of this or other SA species, please email our seedroom.

This page forms part of the South African National Biodiversity Institute's plant information website