66 NEW ZEALAND PLANTS. 



That plants growing in wet stations, such as salt meadows and 

 marshes, should be furnished with appliances to combat drought appears 

 very remarkable. The truth seems to be that for some reason not 

 yet sufficiently explained, although many theories are rife, the plant 

 dare not use too much brackish w r ater, and so is actually in the same 

 position as a plant of a desert region. When dealing with the bog 

 vegetation it will be seen that it, too, is in a similar condition, and so 

 is that in the neighbourhood of solfataras and the like. 



Schimper has summed up these conditions in an excellent manner, 

 pointing out that two kinds of dryness exist. These he has named 

 "physical 5 and "physiological.'' Physical dryness arises from want 

 of water in the soil, but a physiologically dry soil may contain any 

 amount of water, but yet of such a quality that its plant inhabitants 

 cannot use it. To quote a common example, the sea is physiologically 

 dry, so far as man is concerned. Physiological dryness alone concerns 

 plant-distribution . 



SANDY AND EOCKY 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 SoldancUa) 

 (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. 



