xlii BOTANY OF SOCOTRA. 



Graminese is almost as abundantly represented as Leguminosse, and three- 

 fifths of the species are widely-spread plants in tropical regions. It is note- 

 worthy, however, that a new Hordean genus Ischnurus occurs, having affinity 

 with the Indian Oropetium; and another interesting plant is Rhynchelytrum micro- 

 Stachyum, belonging to a little-known genus hitherto found in two species, one 

 inhabiting Abyssinio, and one ^Ethiopia. There are in addition three endemic 

 species of such widely-spread genera as Eriochloa, Panicum, and Lepturus. 



In Composite we have an order represented by species more than half of 

 which are endemic, and not quite one-seventh are weeds of cosmopolitan 

 tropical growth. Of the shrubby character which Composite of insular 

 floras so frequently exhibit we have illustrations in Socotra. Vernonia 

 Cockbumiana is the largest species, forming at times a small tree ; as small 

 shrubs, or rather undershrubs, we have Psiadia Schiveinfarthii, Pluchea 

 aromatica, Pluchea obovata, Pulicaria stephanocarpa, Pulicaria vierceoides, and 

 Euryops socotranus. Of the distribution of the genera of these shrubs, it is 

 noteworthy that Psiadia is essentially a genus of tropical Africa, Madagascar, 

 and the Mascarene islands — but one African species extends into Arabia, and 

 with this Arabian form our Socotran plant has close affinity ; and that Euryops 

 is primarily a south African genus, with, however, a representative in Nile- 

 land and one in Arabia (probably the same form in these localities). Pulicaria 

 is a genus with maximum development in the Mediterranean region, but 

 with outlying forms in south Africa and western Asia ; but I may note that 

 the two Socotran undershrubs referred to here are included in this genus with 

 some reserve, and may probably eventually be excluded from it. Vernonia 

 is a general tropical genus with a Brazilian centre of greatest development. 

 Upon the island these shrubby forms are, with the exception of the Vernonia 

 and Pulicaria stephanocarpa, inhabitants of the higher lands in the central 

 granitic region ; Vernonia, on the other hand, is widely distributed over the 

 island ; and it is to be remarked that when the plant grows upon the dry 

 unfavourable limestone plains of the higher regions, it does not assume an 

 arboreous character, but forms a low, stunted, gnarled, and twisted shrub. 

 Pulicaria stephanocarpa is the commonest undershrub on the plain about 

 Gallonsir. The great development of Helichrysum is a characteristic feature 

 in the flora ; no less than seven species, and all endemic, are known. They are 

 natives of the highest peaks, and such as H. rosulatum, H. aciculare, H. 

 suffruticosum, and H. Nimmoanum have the character of small undershrubs. 

 Senecio Scotti, belonging to the Kleinia section of the genus, which is 

 almost exclusively south African, is another interesting Composite. Its 

 errant position finds a correspondence in that of Senecio longifiorus on the 

 Abyssinian highlands. Dichrocephala chrysanthemifolia was only gathered on 

 the top of the Haghier peaks, and is the plant found at the highest altitude. 



