28 CACTACEOUS PLANTS. 



Cactus continues very scarce, and few collections now include examples of 

 it. Fig. i is engraved from a photograph of one of the Blewberry plants, 

 representing it of the natural size, a single tubercle being shown at the 

 side. 



LEUCHTENBERGIA, HooJwr. 



Few who were unacquainted with Leuohtenbergia principis would, at the 

 ]irst examination of a plant not in flower, think it was a member of the 

 Cactus family ; it is so entirely distinct from all the genera and species 

 in outward appearance, and might be easily mistaken for an Aloe or some 

 relative of the Haworthias. A glance at the flowers would, however, be 

 sufficient to indicate its true position in the vegetable kingdom, as the 

 calyx is somewhat tubular with numerous lobes, the outer scale-like, the 

 interior narrow and spreading, the petals being in two series, coloured 

 like the petals, with indefinite stamens and numerous stigmas. The 

 tubercles are triangular, about 3 to 4 inches long, crowned with several 

 peculiar flattened ashy-grey spines that have •■■ withered appearance, and 

 vary in length from half an inch to 2 or 3 inches. These tubercles are 

 arranged spirally round the stem, and, owing to then- differing so much 

 from the tubercles in Pelecyphora and Mamillaria, they have been the 

 subject of much discussion as to their true nature. The apparent diffi- 

 culty of the matter has been increased by the fact that the flowers are 

 produced near the apex of the tubercles and not from the axil, as in the 

 Mamillarias. Respecting this point also there has been a divergence of 

 opinion, some writers describing it as producing the flowers from the 

 axils and others from the apex. Writing me upon this subject, Mr. 

 E. I. Lynch, Curator of the Cambridge Botanic Garden, observes, 

 '' Lemaire in ' Les Cacttes ' ridicules the idea that the flowers of Leuch- 

 tenbergia are borne at the summit of the mammae, but his information was 

 untrustworthy. It does habitually flower from that position, as I 

 have frequently seen. In some cases the flowers are produced near 

 the apex of very little developed mammse in the centre of the plant, 

 and it would be easy to make a mistake as to the actual origin of the 

 flower, as it is wedged in tightly by the other mamma?. Most flowers 

 that I have seen were, however, borne quite clear of the centre." This 

 is undoubtedly the fact, as I have seen flowers down in the centre as 

 described, and, without removing them, it would be almost impossible to 

 decide whence they sprung ; while, on the other hand, Mr. Corderoy has 

 sent me a sketch showing the flowers quite clear from the other tubercles, 

 and close to the summit, as stated by BIr. Lynch. 



These tubercles therefore appear to be of a compound nature, repre- 

 senting the fusion of petiole and peduncle similar to what occurs in 



