Sandy and Rocky Shores; Seaweeds.

Sandy shores are common enough on the New Zealand coast; and as these, when sufficiently firm, are patronised as playgrounds for our children and ourselves, something as to their plants may be of interest. Such, a shore may sometimes be quite without plants, except for the remains of seaweeds which mark the high-tide limit. Where the shore is sheltered, the shore convolvulus (Calystegia Soldanetta) (fig. 27), with its, lilac-striped flowers, is often present. Here, too, is the home of the tiny buttercup (Ranunculus acaulis), its leaves of three small succulent leaflets flat on the sand, and its little yellow flower buried right up to its neck. The New Zealand spinach (Tetragonia expansa), the succulent Atriplex Billardieri, and the prickly Salsola Kali are also plants of the shore.

Gravelly and rocky shores are richer in plant-life than sandy ones, since they are much more stable. On them in some places a dock (Rumex neglectus) is common. This has a rather stout creeping stem, which enables the plant to make considerable patches on the gravelly shore, where it grows far more luxuriantly than on the peaty ground which it also inhabits. On the stony shore of Foveaux Strait a small plant of the cress family (Lepidium tenuicaule) puts down an enormously long root in quest of the fresh water which flows seaward beneath the stones.

Fig. 27.—The Shore-convolvulus (Calystegia Soldanella), growing on dune, New Brighton, Canterbury.
[Photo, A. H. Cockayne.

Where rocks jut out into the sea, forming pools, there the beautiful red seaweeds have their home; but where the sea dashes with fury, the huge brown ones are found. As two of these are so frequently cast up on the shore, they, at any rate, must be known to most who are acquainted with the seaside. The one (Macrocystis Dubenii) grows to an immense size, and its leaves float upon the surface of the sea by means of their small bladders full of air, while, dozens of feet below, the cord-like stems are anchored firmly to the rocky floor of the ocean. The other (D'Urvillaea utilis) is found in rougher water, its stouter stem showing a honeycomb-like structure when cut into. D'Urvillaea gets its name from the Admiral D'Urville mentioned in Chapter II. By the Stewart Island Maoris its "leaves" are made into bags for holding the preserved mutton-birds.

In the calm waters of the West Coast Sounds, where not too deep, are flower-gardens of the sea, whose loveliness can be seen for considerable depths through the transparent water. Generally speaking, the depth of water determines the distribution of seaweeds. Thus the green ones are found in the shallowest pools, and the red in the deepest, while the brown occupy a position midway, and some of these may be seen writhing like snakes over the glistening rocks at low water (fig. 2). Some seaweeds behave like the perching-plants of the forest, and have taken up their abode on other species.