BOTAXY. 151 



shrubby succulent plants, with opposite or alternate simple leaves. They 

 are found in warm regions chiefly. The greater part of them grow at the 

 Cape of Good Hope. The order has been divided into three sections: 1. 

 Mesembryeae, numerous conspicuous petals, plurilocular capsule, with 

 stellate dehiscence. 2. Tetragonieee, petals 0, fruit woody and indehiscent. 

 3. Sesuvefce, petals 0, capsule with circumscissile dehiscence. There are 

 sixteen known genera, and 440 species. Examples : Mesembryanthemum, 

 Tetragonia, Aizoon, Sesuvium. No species of this order are native to 

 North America. Mesembryanthemum crystallinum is often cultivated in 

 green-houses under the name of ice-plant, so called from the peculiar 

 appearance of the leaves. 



Mesembryanthemum rubrocinctum {pL 69, fig. 5). 



Order 133. Crassulace^e, the House-leek Family. Sepals three to 

 twenty, more or less unÜed at the base. Petals equal to the sepals in 

 number, inserted in the bottom of the calyx, either distinct, or cohering in 

 a gamopetalous corolla. Stamens inserted with the petals, either equal to 

 them in number, and alternate with them, or twice as many, those opposite 

 the petals being shortest ; sometimes one or two rows of abortive stamens ; 

 filaments distinct or united, subulate ; anthers bilocular, dehiscing longi- 

 tudinally or transversely. Abortive stamens or scales (sometimes obsolete), 

 at the base of each carpel. Carpels equal in number to the petals and 

 opposite to them, one-celled, sometimes consolidated ; styles several or 

 combined ; stigmas pointed or four-cornered ; ovules 00, or definite, 

 anatropal. Fruit consisting of several follicles, dehiscing by the ventral 

 suture, sometimes by the dorsal suture. Seeds variable in number ; embryo 

 straight, in the midst of fleshy albumen ; radicle pointing to the hilum. 

 Herbaceous plants or shrubs, often succulent, with simple, entire, or pinna- 

 tifid, exstipulate leaves. They are found in the driest situations, as on 

 rocks, walls, and sandy plains, in various parts of the world. 



Tidbe 1. CrassulecB. Carpels (follicles) distinct ; dehiscent by the inner 

 suture. Sub-tribe 1. Isostemones . Stamens equal in number to the petals. 

 Section a. Eucrassuleae. Examples : *Tillaea, Crassula. Section b. 

 Rocheas. Example : Rochea. Sub-tribe 2. Dlplostemones. Stamens twice 

 as many as the petals. Section a. Umbilicea?. Example : *Echeveria. 

 Section b. Sedeas. Examples : *Sedum, Sempervirum. 



Tribe 2. Diamorphecc. Carpels more or less united, dehiscent by the 

 separation of the dorsal portion. Examples : *Diamorpha, *Penthoruni. 

 So-me of the plants of this order are acrid, as Sedum acre ; Sempervivuni 

 tectorum is known as the House-leek. There are five genera, with twenty 

 species, in North America. 



Sedum acre. Stone crop, Europe {pi. 69, fig. 1) ; a, the plant ; b, a 

 flower ; c, the five carpels ; d, one of the same ; e, f, seeds ; g, leaves. 



Order 134. Surianace^e. Sepals five, persistent ; testivation twisted, 

 imbricated. Petals five, alternate with the sepals, distinct, inserted into the 

 bottom of the calyx. Stamens five, alternate with the petals, sometimes with 

 five alternating ones, that are occasionally abortive, all inserted with the 

 petals ; filaments persistent, distinct, subulate from a broad base, hairy 



151 



