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This is a medium to tall plant, which can be used equally well
in a border or as an accent plant. The plants are very decorative
with silvery foliage like branches and tall silvery or golden brown
inflorescences on velvety stems. They are evergreen and low maintenance
plants suitable for normal garden conditions.
Description
Thamnochortus cinereus is a tufted plant with a fairly small
diameter at the base of the plant, from which the stems fan out
to form a rounded shape, about 1 m in height. The tall male inflorescences
can reach a height of 1.5 m above the foliage. Members of the Restionaceae
family do not have real leaves but the sterile branches at the nodes
of the main stems look just like small, needle-like leaves. The
plants can be treated like small shrubs or perennials and should
reach an age of at least seven years if they are grown in a suitable
spot. They normally start flowering during May or June in the southern
hemisphere and the seed ripens during December. A two-year old plant
can already be in flower and at three years old, the plants are
at their decorative best.
Distribution
Thamnochortus cinereus grows in a wide range of conditions
in the coastal mountains of the southern part of South Africa from
Port Elizabeth to Swellendam. It is one of the most common species
on the cooler south-facing slopes of the mountains, where the plants
get a fair amount of rain or mist. The soils are mostly well drained
but the plants also grow along streams or in seeps where the underground
water runs. Although the plants can grow in fairly wet conditions,
they would not be suitable for a bog garden or at the edge of a
pond where the water is not moving underground. The plants mostly
grow in full sun but can tolerate light shade during part of the
day. They are not frost tolerant and require Mediterranean growing
conditions, i.e. mild, wet winters and hot, dry summers.
Name
The genus Thamnochortus is quite large, there are approximately
31 species growing mostly in the southern part of South Africa.
It is part of the family of Restionaceae, which is widespread throughout
the southern hemisphere and can be found in places as far apart
as Australia, Madagascar, Indo-China and Chile. The family name
of Restionaceae refers to the Latin restis, which means cord
or rope and alludes to the use of the plants in southern Africa.
The species in this genus are mostly tufted plants, but some have
creeping rhizomes with stems which pop up some distance from each
other. The height varies considerably between species, some are
only 300 mm high, whereas T. spicigerus and T.
insignis can reach heights of 3 m with a diameter of also
3 m. T. insignis is the only member of the genus which is
of considerable commercial value and is widely used for thatching
roofs. The species name cinereus refers to the silvery colour
of the female bracts.
Ecology
Like all restios, the male and female flowers are on separate
plants. The flowers themselves are very small and insignificant;
the silvery colouring is produced by the bracts, which surround
the flowers. 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 plants produce a large amount of small, winged seeds. However,
in common with most other species of the genus Thamnochortus,
most of these seeds are not viable. The seed is stored in the upper
layer of the soil and produces the new generation of plants after
a large fire, but the plants also coppice from the base after a
fire.
Uses
The economic use of plants of this family has been limited, as the
plants contain a large amount of tannin and so are grazed only as
a last resort by cattle and sheep. The species that have simple,
unbranched stems are sometimes used for thatching, whereas while
the species with branched stems are used as brooms (besems). Thamnochortus
cinereus has been in planted in gardens since 1994, when it
was propagated and distribution by the Kirstenbosch Botanical Garden.
Growing Thamnochortus cinereus
This restio would look very good in a small group in a mixed border,
in a group in a fynbos garden, in between members of the Protea
or Erica families or in large landscaped areas around an office
block. It will also look attractive in a pot on a patio or terrace.
It is not known how it will react to cold, northern hemisphere climates.
The plants are best grown from seed, which has a fairly good germination
rate when treated with smoke or 'Instant Smoke Plus' seed primer.
It must be taken into account that about half of the seeds will
not be viable, so the seed will have to be sown in an even layer,
covering the soil in the seed pan. This species should be grown
in full sun, in a well-drained soil and have plenty of air movement
around it. The plants adapt to a large variety of soil types. The
best time for planting restios is at the beginning of the rainy
season, as the plants need regular watering during the first six
weeks to two months after planting. After this initial period the
plants can survive with a little additional watering but grow better
with a normal garden-watering regime. They may be fed with standard
organic fertilizers such as Seagro, Kelpak or Bounce Back, or by
sprinkling the surrounding soil with a small amount of ammonium
sulfate during the growing season.
The plants will initially be a bit slow to grow, but will have
formed a handsome plant and flower three years after sowing. The
plants produce a new growth flush in the centre of the plant every
year. The individual stems start to deteriorate during the third
year but by that time already two new flushes of growth will have
appeared for the yearly renewal of the plant. This governs the maintenance
of the plant, which really only needs a regular removal of the brown,
dead stems on the outside part of the plant.
References and further reading
- Brown, N., Jamieson, H. & Botha, P. 1998. Grow restios.
Kirstenbosch Gardening Series. National Botanical Institute, Cape
Town.
- Haaksma, E.D. & Linder, H.P. 2000. Restios of the Fynbos.
The Botanical Society of South Africa, Cape Town..
- Linder, H.P. 1985. A conspectus of the African species of Restionaceae.
Bothalia 15: 387-503.
- Linder, H.P. 1991. A review of the southern African Restionaceae.
Contributions from the Bolus Herbarium No. 13.
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Author
Hanneke Jamieson
Kirstenbosch NBG
June 2004
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