The “Challenger” Expedition *

Abstract

V.INACCESSIBLE AND NIGHTINGALE ISLANDS THE first of these islands, the area of which is about four square miles, is situated about twenty-three miles W. by S. of Tristan d'Acunha. The cliffs rise to the height of about 1,000 feet in a perpendicular range on the north-east side. The tract beneath the cliffs is covered with debris of fallen rocks. On the cliffs themselves the plants are similar to those found in the same situation in Tristan. On the lower land are dense thickets of Spartina arundinacea Carm., a tall, reed-like grass, which here forms an extensive penguin rookery; patches of Phylica arborea Th. also grow on the summits of slight elevations; and under the shelter of the cliffs the trees attain a height of twenty feet, or even more. The trunks are seldom or never straight, but mostly lean over, or become partly procumbent, starting upright again towards the top. The largest trunk seen by Mr. Moseley measured a foot in diameter, but the trees on the upper plateau are said to measure 18inchesacross,theydonot,however,growso high, being stunted by the force of the gales. The wood of the Phylica, though brittle, is said to be useful when properly dried, but in exposed situations it rapidly decays. Underneath the trees are ferns, mosses, and sedges, also Acana sanguisorbce Vahl., the leaves of which are used in New Zealand both as a tea and as a medicine, Chenopodium lomeutosumTh.,_ the tea-plant of Tristan, also grows in abundance, forming bushes with woody sterns. A species of Sphagnum, Carex insularis Carm., and Hydrocotyle cap! tata Th. grew in a swamp near the penguin rookery. From the two Germans who were discovered on the island a goo i deal of information was obtained about the vegetation, more especially of that of the higher land, to which it was found impracticable to ascend from the side of the mountain where the ship anchored. The plants found there were similar to those which grewbelow, but in addition grew the species of Empetrum, found on the other islands, Lomaria boryana Willd., which in some instances attained a height of four feet, Lycopodium insulare Carm., and Lage-nophora commersonii Cass., a small Composite plant with a daisy-like flower. The Tussock grass, which appears closely similar to Daclylis ccespitosa Forst., of the Falk-lands, grows in patches of considerable size on the upper plateau, and straggles up the cliffs to the summit. Nertera depressa Banks also grows on the plateau, and its berries form a favourite food of the Nesocichla eremita, the native thrush of the Tristan group; while the Bunting {Emberiza brasiliensis) feeds on the fruits of the Phylica.