160 BOTANY OF SOCOTRA. 



and only about a foot and a half high, and from the top of this rise a few rapidly 

 tapering branches, each ending in a small tuft of leaves, or, it may be, in a truss 

 of beautiful pink flowers. 



There has been great confusion in the nomenclature of the species of 

 Adenium from Arabia and tropical Africa, and I may here attempt to clear up 

 the confusion. 



Rcemer and Schultz (Syst. iv. xxxv, and 411) constituted the genus Adenium 

 for a plant collected by Forskal in the vicinity of Melhan in Arabia, north-west 

 of Mokha, which he shortly described — (Fl. yEgypt. Arab. 205) — under the 

 name Nerium obesum, thus: — " foliis sparsis oblongis ; ramis loriformibus- 

 Caudex mollis, bulbum referens supra terram, volumine capitis humani." 



It is to be observed that he does not say anything as to the texture or the 

 indumentum of the leaves. Vahl (Symb. ii. 45.) gives, under the same name, 

 a fuller description of Forskal's plant, and there is no reason to doubt that his 

 description was founded on Forskal's specimens. His description of the leaves 

 is as follows : — " folia oblonga ad apices ramorum, approximata, subpetiolata, 

 saepe tripollicaria, basi angustiora mucronata, avenia: subtus villoso-tomentosa : 

 juniora utrinque mollia." 



G. Don (Gen. Syst. iv. 80) takes up this same plant under Rcemer and 

 Schultz's name Adenium obesum (Adenum he writes). But Sprengel (Syst. 

 Veg. i. 641) refers to it as Cameraria obesum. Alphonse De Candolle (Prod, 

 viii. 412) rightly reverts to the generic name Adenium, and in addition to Ad. 

 obesum, Rcem. and Schult., he describes a second species, Ad. Honghel, a west 

 tropical African form, which is quite a distinct one, having glabrous leaves and 

 the corolla tube internally glabrous. 



Now in the Botanical Register, xxxii. t. 54, we find a figure and a descrip- 

 tion purporting to be of Ad. Honghel, DC. The description is quoted from De 

 Candolle's Prodromus, and is that of Ad. Honghel, but it does not apply to the 

 figure, which is that of a species found at Aden, and not the west tropical African 

 plant. This Aden plant is the one which has always been best known, and was 

 introduced into cultivation and flowered in Britain prior to 1841. But, strange 

 to say, it has never been correctly named. T. Anderson (in Journ. Linn. Soc. 

 v. (1860), Suppl. 23) describes the Aden plant as Ad. obesum, Rcem. and Schult., 

 and under this name it has become generally known, — and he supposed it to be 

 Forskal's plant, and the one referred to by Don and Sprengel, and also the 

 species Ad. Honghel of the Botanical Register, though not of De Candolle. 



He refers to the leaves as " ellipticis ovatis v. spathulatis glabris." 



This is a correct description of the Aden plant, but it evidently refers to one 

 very different from Forskal's plant, — the one described by Roemer and Schultz ; 

 and whilst it suits the figure under Ad. Honghel, in the Botanical Register, to 

 which he refers, yet the description there given is, as I have said above, of a 

 different species, viz., of the true Ad. Honghel, DC. 



