CRASSULACE2E. 31 5 



reduced it, under the name Joubarbes (Seda), to a smaller number, which 

 would have been quite naturally associated had Suridna and Tetracera 

 been omitted. A. L. de Jussieu 1 in 1789 finally removed these 

 two from his order Semperviva. Ten years later Ventenat 2 named 

 the group Succulent^. 3 It at length received the name Crassulacea in 

 the memoirs of A. P. De Candolle 4 at the beginning of this century. 

 Herein he included, besides the numerous genera that had been split 

 off from Sedum, Sempervivum, Crassula, &c, the genus Penthorum, of 

 which Jussieu had only made a genus affine, and which we shall refer 

 to Saxifragacece. Of all these genera we shall retain only the seven 

 referred to above, including Triactina, founded by J. Hooker and 

 Thomson in 1S57. 5 



These eight genera contain about four hundred species. 6 Most of 

 the genera are cosmopolitan ; Sempervivum, Bri/opliyllum, and 

 Triactina alone appear peculiar to the Old World. But if Crassula, 

 Sedum, Kalanchoe, and Cotyledon are represented in America, it is 

 but by very few species. Only one Kalanchoe occurs in Brazil, 

 several Cotyledons in Mexico, and a few Sedums, besides Dlamorpha, 

 in both North and South America. 



The Crassulacece are all succulent plants, and hence have a 

 peculiar habit. The stems, and the leaves (in a yet higher degree), 

 are thick and fleshy, with a rich succulent parenchyma, gorged with 

 fluid. The vascular elements, few in proportion, often assume an 

 arrangement corresponding with the form of the organs. When the 

 leaves become thick and cylindrical, thus resembling the axes, the 

 fibrovascular bundles are distributed in a circle around a central line 

 occupied by fleshy parenchyma, like that which is found between the 

 several bundles. In several genera, and notably in several House- 

 leeks, 7 there are no true medullary rays, but only so-called medullary 



1 Gen., 207, ord. i. ; in Diet. Sc. Nat., xi. 

 (1818), 269 (Crassulce). 



2 Tall., iii. 271 (1799). 



3 Linn-ETTS had united under this name, in 

 his Ordines Naturales, a large number of very 

 diverse fleshy plants, the same as Hawobtii did 

 in 1812 in his celebrated Synopsis Plantariim 

 Succulentarum (Lond., 8vo), wherein a large 

 number of Crassulacea are studied with the rest. 



4 Hist, des PI. Grasses (1799-1829) j Mem. 

 sur la Fam. des Joubarbes [in Bull. Soc. 

 Pkilom. (1801), 1] ; Mem. sur la Fam. des Cras- 

 sulacees, Paris, 4to (1828) ; Prodr., iii. (1828), 

 381, ord. 87. Speengel calls them Sedece. 



5 In Joum. Linn. Soc, ii. 90. 



6 Lindley counted 450, in 1846, in his 

 Vegetable Kingdom (346, ord. 120). 



7 Ad. Be., in Arch. Mus„ i. (1S39), 437. 



