484 ECOLOGICAL STUDY OF SALTMARSH VEGETATION. 



progress is arrested and it sickens, turns black, and dies. On 

 the demise of the premier shoot, a series of laterals issues from 

 the inner joints and advances en masse, but is compelled to 

 either turn aside or meet the fate of the leader (Plate xix., 

 fig. 6) . The Sporobolus lawn on the detritus mounds provide? 

 a refuge for a series of miniature colonies, small groups of a 

 species, or individual plants, chiefly ruderals of annual or 

 biennial growth, and a root system usually vertical descending 

 below that of the Sporobolus. The Orache, Atriplex patula L., 

 a weedy annual introduced from Europe, is occasional on these 

 mounds though the bulk of its herbage is disposed in the vacant 

 spaces of the Seahlite-Salicornia formations, isolated plants occa- 

 sionally reaching the verge of the Mangroves. In areas where 

 the conditions are exceptionally favourable it frequently grows 

 in dense patches, reaching a height of 3 feet and temporarily 

 excluding the lower growths by overshadowing them with its 

 close fleshy foliage. A luxuriant growth of the Orache was 

 noted on the marsh plain at Homebush Bay, and a ribbon-like 

 colony was seen at Hen and Chickens Bay crowning a low bank 

 on the margin of a drainage channel. The colony at Hen and 

 Chickens Bay was interspersed, in December, with young plants 

 of the New Zealand Spinach, Tetragonia expansa Murr. In the 

 following June this locality was again visited and the Atriplex 

 had ripened its fruits and was rapidly dying; the Tetragonia — 

 also an annual — having developed the bulk of its heavy foliage, 

 dominated the position. These plants were noted, in several of 

 the estuaries visited, in mutual occupation of an area under a 

 similar phenological arrangement. The invasion of the salt 

 plain by the Orache is ephemeral, its brief existence passing and 

 permitting the reappearance of the lowly marsh herbs. Its 

 leaves are encrusted with an excretion of salt which, in addition 

 to relieving the plants of an injurious deposit, affords the leaves 

 a measure of protection from the intense insolation prevalent in 

 this station. The Orache is widely distributed in temperate 

 regions and owes its dispersal to the agency of both currents and 

 birds. Guppy (13, p. 537) lists the fruits as floating for six 

 months. [Seeds, released from the calyx in which they are 

 enclosed and stripped of their membraneous coat, sank at once 

 — A. A. H.] The capsules of the New Zealand Spinach floated 

 for a week, the dried epicarp supporting the weight of the bony 

 endoearp until saturated. 



