WAYS OF THE WILD.

Auckland Star, Volume LXI, Issue 57, 8 March 1930, Page 2 (Supplement)

WAYS OF THE WILD.

A NATURALIST'S NOTEBOOK, NEW ZEALAND'S SEAWEEDS. (By A. T. PYCROFT.) ~ „ A correspondent, "Dulse," wishes $6 know in what localities New Zealand edible seaweeds are to be found, how to recognise them and how to prepare them for food; also, the Maori and scientific names of various sorts. The Algae, Latin Alga, seaweed are divisible into threa main groups—the brown and black, such as kelp, a word of unknown origin, but referring to the large brown and black seaweeds; dulse, a seaweed of a reddisu brown colour, which is sometimes eaten, as in Scotland; carrageen, a small purplish branching cartilaginous seaweed which, when blanched, is the Irish moss of commerce, and is a gelatinous productobtained from species of gigartina cllOKdrus and gracilaria, of which genus we have numerous representatives. From one species the Chinese obtain a valuable cement. Sea lettuces, or sea cabbages, are seaweeds with green paper-like fronds. These are also sometimes eaten as food. They belong to the genus ulva, from the Latin a sedge. Great Variety. New Zealand's authority on our seaweeds is Mr. R. M. Laing, Fellow of tne New Zealand Institute, whose iirst paper on seaweeds appeared as far back as 18S5. A recent paper by this authority was published in the "Transactions of the New Zealand Institute" in 1927. Laing states: Our first knowledge of New Zealand seaweeds commenced with Cook's first voyage. Marine algae arn not 'so widely distributed as might on first thoughts be imagined; indeed, it might be supposed that the only limitations to their distribution would be due to unsuitable environment, but this is by no means the case. In spite of the great geological age of this class of plants and their marine habitat, many of them are local in distribution. Mr, W. Martin, author of a recent work, "The New Zealand Nature Book," state? that every station along the New Zealand coastline from the spray-drenched; cliffs above high-tide mark to a depth of many fathoms supports its quota or the live hundred species of marine algac v or seaweeds, that inhabit this region. This great variety is. in measure a reflex of the wide latitudinal range of tin coastline, but to a greater degree it ia due to a complex of factors, chief ii. which are the intensity and quality of the light, the temperature and salinity of the water, the depth, the duration o£ daily exposure to the air, and the degree of shelter present. Each species is as a rule limited to one zone or station, and hence comparatively few algae range along the whole coastline. The deep sea is, generally speaking, a barrier between the species and so are long reaches of sand, and the mouths of large rivers, The open ocean, however, is not devoid of its seaweeds. These are surfacefloating weeds, like the gulf weed, a branching seaweed, sometimes_ called tbe sea grape, on account of its having numerous berry-like air vessels, This weed is found in the Gulf Stream, in tho Sargasso Sea, and elsewhere. Many species of sargas--um, of which the Gmi weed is probably the best known exotic example, are met with round the eoas's, particularly of the North Island. Thess have sma 1 ! spherical, or more rarely elliptical, floats, borne on short stalks originating near the bases of the fronds. The stems are flat and the leaves possess a distinct midrib.

Food and Medicinal Value of Seaweeds,

My correspondent "Dulse" expresses the opinion that there is such a lot of exopthalmic goitre prevalent in JS«ew Zealand, preventable only, as far as is known, by the ingestion of iodine in organic form, that 'the spreading of information on the rendering available for food of such substances as seaweeds with their large iodine content cannot but be of the greatest public benefit. Little is- at present known of the food value of New Zaaland seaweeds. Laing states that different kinds have considerable medicinal value, real or imputed, and that the use of seaweed has been suggested as a cure for goitre, so prevalent in New Zealand. Seaweed is already an ingredient in various cough cures. There is little doubt but that the vegetable harvests of the sea will become more and more valuable. The Japanese cultivate certain species. The Maori used two species of kelp or laminaria medicinally. Species of the genus laminaria are usually found in from two to ten fathoms of water. The fronds commonly grow in clusters, and are from thirty to fifty feet in length. One species, known to the Maori _ as rimu-roa, was used as a cure for itch and intestinal worms. The tender leaves were 1 oaf ted and eaten. Another species of laminaria, known as karengo, was fomented with the sweet juice of the poisonous tutu and used as an aperient. It sets as a jelly, and was eaten when cold. This seaweed was also dried and packed away in baskets for future use, and as a present to inland friends. Rimu-rapa (D'Urvillea Antarctica) and Rehia (gigartina) were also mixed with the sweet'juice of the tutu and eaten as a jelly when cold. Raw seaweed, the general name of which is riniu, was used by the Maoris in the ceremonies of the whare-kura or the house of learning. Seaweed was also the sacred offering in place of the slain sacrifice. Kohukohu was another seaweed used in sacred rites, but I am not sure to what species it belonged.

What Seaweeds Are. Seaweeds possess no true roots, stems, leaves, flowers, fruit or seed. They are spore bearing plants, and so do not need the same organs as do flowering plants. Roots serve to take in nourishment, but the seaweed is able to absorb food with its whole surface, and so in place of roots' it has at most an enlarged "holdfast" by means of which it is glued to the rock for security. The longer seaweeds are remarkably buoyant, due to large air-filled cells or air-filled floats. Almost all are tough, light and pliant. The Southern Maoris split the fronds of the giant kelp and make a bag in which they pack mutton birds. In one respect the seaweeds are similar to laud plants. Both, when growing in shade, develop long spaces between the points of The stem from which the leaves arise, while strong light has a stunting effect. Thus the deep-water, shade dwelling species are mostly of slender or attenuated habit. Propagation in seaweeds i% effected both sexually and without sexual action. In some, small leads or leaflets, on becoming detached, can give rise to new individuals. The green seaweeds develop either by cell-division or by spores. The spores, of such species as produce them, are carried in external receptacles, or in conceptaeles sunk: below the surface of the frond.