220 THE CEASSTTLA FAMILY. 



of the flower of the different whorls forms the most prominent character 

 of the family, to which the succulent leaves give a peculiar habit. 



Stamens 3 or 4. > Plants very small, with minute flowers 1. TlLLXA. 



Stamens twice as many as the petals (half of them sometimes without 

 anthers). 

 Petals united in a tubular corolla, longer than the calyx ..... 2. CoTTtEDON. 

 Petals free or nearly so, and spreading. 



Flowers mostly with 5 or 6 petals and sepals 3. SEDtiM. 



AH the flowers with more than 6, usually 10 or 12 petals and sepals 4. Houseleek. 



Among the succulent plants in our greenhouses, the Ci-assulas, Eche- 

 verias, Eocheas, and a few others, belong to this famUy, but by far the 

 greater proportion form part of the MesembryantTiemum and Cactus fami- 

 lies, which are entirely exotic. 



I. TIIiI..flE:A. TILL^A. 



Very small annuals, with opposite leaves, and minute flowers in the upper 

 axils. Sepals, petals, stamens, and carpels 3 or 4. 



Besides the European species, the genus contains several from North 

 America, central Asia, southern Africa, and AustraUa, most of them amongst 

 the smallest of flowering plants. 



1. Mossy Tillsea. Tillsea xnuscosa, Linn. 

 (Eng. Bot. t. 116.) 



The whole plant is seldom more than 2 inches high, and usually but an 

 inch, or even much less, although much branched, and crowded with flowers ; 

 it is usually of a reddish colour, and slender, though succulent. Iicaves 

 narrow-lanceolate or linear. Flowers solitary in each axU, or several to- 

 gether in little clusters. Sepals lanceolate, pointed. Petals minute and 

 subulate. Carpels with 2 minute seeds in each. 



On moist, barren, sandy heaths and wastes, in western and sovtthern 

 Europe, extending eastward round the Mediterranean, and northward to 

 the Netherlands. Has been foimd in several of the southern counties of 

 England, but not in Ireland or Scotland. Fl. swnmer. 



II. cotvzjEdon. cotyledon. 



Herbs, or succulent shrubs, with scattered leaves (rarely opposite in some 

 exotic species), and flowers in terminal racemes or panicles. Sepals 5, 

 small. Petals combined into a single tubular or campanulate corolla, with 

 5 teeth or divisions. Stamens 10, inserted at the base of the corolla. Car- 

 pels 5, each with a scale at the base. 



Taking this genus in the sense in which it was understood by Linnoeus, it 

 includes a considerable number of south-west African, besides several south 

 European and central Asiatic ones, which, with our British species, are 

 considered by some modern botanists as forming a distinct genus under the 

 name of Uinhilicus. 



1. IVall Cotyledon. Cotyledon umbilicus, Linn. 



(Eng. Bot. t. 325. Pennywort. Navelwori.) 

 Stock perennial, almost woody. Radical and lower leaves on long stalks, 

 fleshy, orbicular, broadly crenate, and more or less peltate. Flowering 

 stems erect, from 6 inches to a foot high, simple or shghtly branched, leafy 



