INTRODUCTORY CHAPTER. ; 



x 

 and amongst Liliacese there are only two bulbous forms, both new, one brought l 

 the English and one by the German expedition. Of the eight species of Liliacet, 

 known, six are endemic, and one of the other species is represented by an 

 endemic variety. By far the most interest attaches in this family to the 

 existence of Aloe Perryi, the source of the Socotran aloes, and to Dracaena 

 Cinnabari, the Socotran dragon's-blood tree. Both are endemic plants. The 

 alliance of the Socotran Dracwna with the Canary Island tree, with that of 

 Abyssinia and with one recently found in Somali-land, is a fact of leading 

 importance in geographical distribution. 



Cruciferse, Caryophylleae, and Urticacese come next in numerical import- 

 ance. Cruciferse is chiefly remarkable for an endemic genus, Lachnocapsa, the 

 affinity of which it is difficult to determine. In Urticacese we have another of 

 the remarkable plants of the flora, namely, Dorstena gigas, which is a low-grow- 

 ing plant, which possesses a thick gouty stem, from which a yellow viscid juice 

 exudes. The occurrence of the south African Australina capensis is a curious 

 fact of distribution in this family. 



Verbenacese, which, like Naiadaceae, has six species, half of them being 

 endemic, has an endemic genus Coelocarpus, the affinity of which arrests 

 attention. The closest relationship appears to be to Citliarexylmn, a tropical 

 and subtropical American genus, spreading from Brazil and Bolivia to Mexico, 

 and so close is the affinity that it is only in the andrcecium technical characters 

 of separation are found. 



Of Crassulaceae, Ficoidese, Umbelliferse, Ebenaceae, and Orobanchacese, 

 each with five species, Umbelliferte alone calls for mention here, and that 

 because of its containing an endemic genus, Nirarathamnos, belonging to the 

 affinity of Bnpleurum. It is an elegant woody undershrub, growing only on the 

 higher peaks of the central granitic region of the island. 



Of seven orders which have each four representatives, — Hypericinese, 

 Zygophyllese, Anacardiacese, Lythrarieae, Plumbaginese, Gentianeae, and Com- 

 melinaceae, — Anacardiaceee and Gentianese have each three endemic species. 

 In the first of these two orders, one of the endemic species, Rhus thyrsijiora, 

 which is amongst the commonest tree on the island, has affinity amounting 

 almost to identity with R. paniculata, a plant only known from Birma and 

 Yunan; and the two others are species of Odina, one of which, O. asplenifolia, 

 yields a false frankincense like the nearly related 0. obovata of Somali-land, 

 the other being the ukshare, uksha, or eksche of the inhabitants, one of the 

 largest trees of the island. In Gentianese there are three very pretty endemic 

 species of Exacum, one of which, E. affine, has been introduced to cultivation in 

 this country ; E. cceruleum, from the higher parts of the central granitic region, 

 is however the prettiest species. Lythrarieae has only one endemic species, but 

 that one possesses as much interest as any plant in the flora. Punica protopunica, 



