Omver. — Vegetation of the Kermadec Islands. 133 



with salt spray are too severe, the result being that the upper exposed 

 twigs of all the trees are dead. 



The top of Dayrell Islet supports a very scanty vegetation. The soil 

 is everywhere undermined by burrowing shearwaters, and is in every way 

 similar to the steep slopes of Meyer Island. There are a few small trees 

 of Metrosideros villosa of a straggly habit, while Myoporum Icetum and 

 Coprosma petiolata form low dense bushes about 1 m. high. 



(d.) Sand Duties. — The only true sand dunes on Sunday Island form a 

 single line fringing Low Flat Beach on the north coast. They are low, and 

 consist of the fine sand of which the beach is composed, heaped up by 

 wind against the land. They are covered Avith Ipomosa pes caprce, which sends 

 its runners two or three metres on to the beach itself, and its long white 

 roots still further under the beach. Among the Ipomoea are found chiefly^^ 

 Imperata Cheesemani, Scirpus nodosus, Eleusine indica, and Apium prostratum. 



(e.) Gravel Flat.— A flat extends along the beach in Denham Bay for 

 about 2 km., and has an average width of 75 m. Its outer edge coincides 

 with the limit of storm seas and shifting gravel ; along its inner edge is 

 forest. The vegetation of this flat forms an important plant formation, 

 as in Denham Bay seeds of plants brought by ocean-currents and washed 

 ashore are most likely to find a suitable place for germinating. 



The principal plants of the gravel flat are Ipomoea pes caprce, Mariscus 

 ustidatus, Scirpus nodosus, Sccevola gracilis, Myoporum Icetum, Ageratum 

 conyzoides, Stellaria media, Euphorbia Peplus, Cynodon Dactylon, Calystegia 

 SoldaneUa, Tetragonia expansa, Deyeuxia Forsteri, Imperata Cheesemani, 

 and Erechthites prenanthoides. 



Ipomoea pes caprce has long, branched, trailing stems, which lie along 

 the ground, rooting here and there at the nodes. Leaves large, 2-lobed, 

 dark yellowish-green, firm in texture, forming a mass of vegetation cover- 

 ing the ground to a height of 30 cm. Flowers large and conspicuous, pale 

 lilac, produced in abundance. 



SccBvola gracilis is a procumbent undershrub with long, spreading, hairy 

 branches, and rather dense hairy foliage, covering the ground to a height 

 of about half a metre. Leaves 114 x 39 mm., 110 x 42 mm., 97 x 35 mm., 

 80 x 25 mm., yellowish-green, firm in texture, covered with short stiff hairs. 

 Flowers small, axillary, white with a yellow centre, produced abmidantly 

 throughout the year. Fruit fleshy, white. 



Myoporum Icetum occurs on the gravel flat as low shrubs, 1-3 m. tall, 

 with dense light-green foliage, through which project numerous dead twigs. 

 Detached plants only are found, with the foliage on the seaward side reach- 

 ing the ground. 



The grav(d flat is said to be covered by hurricane seas only, though 

 other heavy seas sometimes break over parts of it, killing some of the vege- 

 tation. In July, 1908, the sea flooded part of the flat, and killed Ipomoea 

 pes caprce, and some of the leaves and twigs of Myoporum Icetum. 



The soil is gravel, similar to that of which the beach is composed. During 

 westerly weather it is continually drenched with salt spray. 



From October till April, wideawake terns {Sterna fidiginosa) occupy 

 the front portion of the gravel flat, and keep the vegetation well trampled 

 down, ^\^len they depart, however, the Ipomoea pes caprce grows up tall 

 and rank, covering the ground with dense dark-gTeen foliage to a height 

 of 40-50 cm., and elsewhere a host of weeds, chiefly Stellaria media and 

 Euphorbia Peplus, soon springs up. 



