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
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
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.
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)
Kirstenbosch Botanic Garden.