PHANEROGAMS — PROFESSOR BAYLEY BALFOUR. 47 



Order XX. RUTACE^E. 



A large order, spread over temperate and warmer regions of the whole world, 

 but attaining a maximum in south Africa and Australia. Of the three genera 

 found in Socotra, two are old-world genera with species often cultivated, and 

 the third is otherwise only known in two species from Texas and California. 



1. RUTA. 



Ruta, Linn. Gen. n. 523 ; Benth. et Hook. Gen. PL i. 286. 



A considerable genus, characteristic of the Mediterranean region and 

 Atlantic islands, and sparingly spread in western and central Asia. 



R. graveolens, Linn. Sp. 548 ; DC. Prod. i. 710 ; Boiss. Flor. Orient, i. 

 921; Oliv. Flor. Trop. Afr. i. 304; Hook. fil Flor. Brit. Ind. i. 485. 



var. angustifolia, Hook. fil. (he. cit.). 



B. angustifolia, Pers. Synops. i. 464 ; Wight and Arn. Prod. 146. 



Nom. Vern. Shedah (B.C.S.). 

 Socotra. Near Tamarida. B.C.S. n. 434. 

 Distrib. From the Canary Islands to Scindh. 

 Probably an escape in Socotra. 



2. THAMNOSMA. 



Thamnosma, Torr. et Fr^m. in Fremont 2nd Eep. (1845), 313, and Bot. Whipple Exp. 17, t. 3 ; 

 Benth. et Hook. Gen. PL i. 288. 



A tritypic genus, which has been hitherto known from the new world only, 

 and there represented by two species, one, T. montana, on which Torrey and 

 Fremont founded the genus brought from mountain passes in California, and 

 obtained later by Bigelow during the Whipple Expedition ; the other, a Texas 

 and north Mexico plant, described and figured by Gray (Sprague and Gray Gen. 

 111. ii. 143, t. 155) as Rutosma texana. It is a fact of no little interest to find a 

 third species turning up on the hills of Socotra, nor is it any the less so when 

 we find that besides the genus Peganum represented by one species, this is the 

 only genus of the true Rues found in the new world, and the only one indigenous 

 in Socotra. The genus is a very distinct one, marked by its peculiar papulose 

 appearance and simple leaves, and separated from all the Kuteae by its 8-lobed 

 disk and the bicarpellary ovary. The Socotran species necessitates an emenda- 

 tion of the generic character, to the extent that the ovary is sometimes sessile, 

 not always stipitate. In Kew Herbarium is a plant from the Transvaal, 

 collected by Dr Atherstone, which is not far removed from this genus. The 

 floral characters are alike, and the general glandular papulose covering is 

 present. It differs, however, in the leaves, which are compound, not simple. 



