12 
THE SEAWEEDS 
rather irregular lobes, and the seed is set free. This is nearly as long as 
the pericarp, is almond-shaped, and is provided with a thin wing along 
one edge, so that it floats and is easily dispersed. In North Tasmania the 
fruits ripen towards the end of December. 
The Australian species is P. australis J. Hooker. 
The fibre of Posidonia is of commercial value, having a breaking strain 
only slightly less than that of jute. Possible uses suggested by the Imperial 
Institute, the South Australian Department of Chemistry, and the Com- 
monwealth Institute of Science and Industry, are (1) as a diluent of 
wool in the manufacture of low grade fabrics, (2) for the manufacture of 
guano bags, horse-blankets, etc., (3) as an insulating agent for heat, (4) 
as a substitute for jute in the backings of oilcloth and rugs, (5) as a sub- 
stitute for horsehair or kapok in bedding and upholstery, and (6) for 
papermaking. On the north-eastern beaches of Spencer and St, \ incent 
Gulfs accumulations of drift material have formed deposits of fibre mixed 
with sand extending over square miles and in places 7ft. deep. Vaiious 
companies— British, Australian, and Dutch— have exploited these deposits 
with a measure of success, but have been hampered by the preliminary 
difficulties of cleaning and drying the fibre. The final product is known 
in the market as Marine Fibre. 
Zoster a, the Sea-Wrack, or Eel-Grass, has a tough creeping rhizome fixed 
firmly by roots, from which spring at intervals shoots with long narrow 
leaves like blades of grass borne alternately on the shoots. The leaves 
may be a foot long and are about a line wide. The flowers, when they 
form in the summer, are enclosed in the leaf -sheath ; they are numerous 
and sessile on a flat band-like stem. Each inflorescence consists of a spike, 
bearing male and female florets in alternate rows. There are no sepals 
or petals, the anther is solitary, as is the ovulary and therefore the fruit. 
There has been much confusion among authors as to recognition of 
species, resulting in much synonymy. Of the three species which we may 
recognise as Australian, one ( Z . capricorni Ascher.) is a northern form, 
and two others are common in the south. The latest worker on the genus, 
Professor Setchell, of the University of California, who has studied much 
Australian and Tasmanian material and has had access to Irmisclvs 
original plants and notes, writes me: “In tasmanica G. von Martens the 
vascular bundles are always more than 3, viz., one central one and 3 to 
5 on each side of it just between the outer cortex and the inner cortex. In 
Z, Muelleri (Irmisch) Ascherson, the vascular bundles are 3, viz., one 
central one and one on each side of it in a similar position to the more 
numerous lateral vascular bundles of Z. tasmanica. 
Zostera fiats afford feeding grounds to a number of marine animals. In 
the north the Dugong ( Ilalicore dugong Gmelin) pastures on the ‘‘Eel- 
Grass” and rejects seaweeds proper. Both Zostera and Posidonia absorb 
iodine from the sea water, and store it in small quantities as a component 
of an organic compound. 
