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NEW AND OLD SPECIES OF MESEMBKYAKTHEMUM. 



53 



V 



New and Old Species of Mesemhryantliemum^ with critical notes 



By N. E. Brown, A.L.S. 



(Plates 5-10.) 

 [Read 6tli February, 1919.] 



The object of this paper is twofold in its nature. First to describe some 

 new species of Mesemhryantliemum that are in cultivation, and in the second 

 placo I wish to demonstrate to future monooraphers the necessity for a 

 thorough revision of the nomanclature of this interesting genus, as in the 

 later monographs of it I have found that there are many errors in identiti- 

 cation. In justification of the latter remark it is necessary that I should 

 aive the details which follow concerning the history of the genus. 



For the bulk of our knowledge of tlie genus iMesemhDjanthemum v:q are 

 indebted to Ha worth, who between 1794 and 1821 published four monographs 

 of this genus. He was the first to make a systematic classification of its 

 specieSj and as he described from liA^ng plants, chiefly cultivated by himself 

 or at Kew, and had a thorough knowledge of them, he made very few 

 mistakes as to species ; and his grouping of them into sections has been 



(apart from a shufHing of their sequence) 



the present time. 



Avery large proportion of the known species were described by him ; but in 



many cases his descriptions are inadequate for identification, as they are 



often only comparisons w^lth other known species, yet they are accurate as 



far as they go. Fortunately, it happens that a large number of his species 



are represented in the Kew Herbarium by a series of excellent coloured 



drawings made from the type plants, so that the majority can be correctly 



Georoo Bond and Thomas 



determined. These drawings were 



mad 



Duncannon, two skilful artists who were employed at Kew Gardens between 

 1822 and 1835 to make drawings of the plants cultivated there. The result 

 is that there are now preserved in the Kew Herbarium many hundreds of 

 good coloured drawings of plants belonging to a large umnber of natui'Ml 

 orders cultivated at Kew at that period, some of them being made from type 

 plants of Alton's ' Hortus Kewensis/ These drawings are all unpublished, 

 and their existence is, I believe, generally unknown. I therefore desire to 

 call the attention of Botanists to them. About a quarter of these drawings 

 rejjresent succulent plants, including \ery nuuiy described by Ha worth, and 

 therefore depict his types, the drawing being in many cases all that exists to 

 frive us a true conception of what some of his species vyere like. 



As many of the drawings of Mesemhryanthemum will be found upon 

 compiirison with the plant to be coloured too green, it maybe w(dl to explain 

 to those who have not cultivated these i*lants that this may be (hie to many 



LIKN. JUUKN. — IJOTANY. VOL, XLV. 



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