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Graminae
Common names
Hairy spinifex, rolling spinifex, spring rolling grass, beach
spinifex (Australia).
Description
A stout, dioecious, perennial grass, up to 30 cm tall, with
strong, creeping stolons which root at the nodes. Plants are vegetatively
similar, some male, some female or bisexual. The male inflorescence is
a terminal cluster of stalked racemes, each cluster subtended by large,
partly enclosing, silky-hairy bracts. The female or bisexual inflorescence
is a large, globose, spiny head of numerous sessile racemes, each of which
is reduced to a single spikelet, which is enclosed by a large, silky-hairy
bract, the axis extending beyond the spikelet into a long, stout bristle,
10 cm or more in length (Tothill & Hacker, 1973).
Distribution
Australia, New Caledonia and New Zealand.
Season of growth
Perennial.
Soil requirements
It is essentially a plant for dune sands and sands of the sea-shores.
Sowing methods
Seed will not germinate in the presence of light, and so must
be buried in the sand by drilling. It can be propagated by cuttings.
Sowing depth and cover
Seed must be sown deeper than 1.25 cm to exclude light, but
no deeper than 3.75 cm to ensure good germination. Deeper sowing leads
to rotten seed in waterlogged conditions (Harty & McDonald, 1972).
In the field, a depth of 3 cm has given satisfaction. Sown areas can be
covered with brush wood.
Seed treatment before
planting
Apart from removing the caryopses, soaking the seed in either
fresh water or sea water does not improve germination (Harty & McDonald,
1972).
Grazing management
It is unpalatable to stock.
Optimum temperature for
growth
Best temperatures for germination of the caryopses were 15-25°C
and 20-35°C.
Natural habitat
Sea-shores.
Genetics and reproduction
2n=18 (Fedorov, 1974).
Seed production and harvesting
Inflorescences of beach spinifex have been harvested from open
beach sites by hand and stored in hessian bags. Spikelets (the caryopsis
enclosed in its lemma, palea and glumes) are usually attached to all or
part of their associated spines. They were obtained from the inflorescences
by several methods, the best of which was the use of a barley de-awning
machine. This consisted of a cylinder, containing a centrally mounted spindle
carrying long metal fingers, which rotates between fixed metal fingers
attached to the inner surface of the cylinder. With this machine the spines
were uniformly clipped short, and spikelets obtained in this way were free
flowing and suitable for mechanical sowing Hammer milling gave a high yield
of caryopses, but was responsible for a great deal of breakage as the caryopses
are soft. Partial threshing of the inflorescences, followed by winnowing,
would help protect the caryopses from damage (Harty & McDonald, 1972).
Further reading
Barr, 1965; Harty & McDonald, 1972; Maiden, 1894.
Dormancy
Seed has no after-ripening requirements (Harty & McDonald,
1972).
Value for erosion control
It is excellent for the stabilization of sands on the sea-
shore due to its vigorous stoloniferous habit. One plant can colonize a
considerable area (Tothill & Hacker, 1973). It is used a good deal
on the coasts of Australia, New Zealand and New Caledonia. It is also used
in reclaiming coastal dunes after mining for zircon and rutile (Barr, 1965).
Tolerance to salinity
Excellent. It is continually exposed to salt-water spray.
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