162 



have the ovaria concrete. Some are monopetalous, particularly the genus 

 Cotyledon. Petals and stamens often almost hypogynous. Tillsea has defi- 

 nite ovules. 



Essential Character Sepals from 3 to 20, more or less united at the base. 



Petals inserted in the bottom of the calyx, either distinct or cohering in a monopetalous 

 corolla. Stamens inserted with the petals, either equal to them in numl)er and alternate 

 with them, or twice as many, those opposite the petals being shortest, and arriving at 

 perfection after the others ; Jilaments distinct, subulate ; anthers of 2 cells, bursting length- 

 wise. Hypogynous scales several, 1 at the base of each ovarium, sometimes obsolete. 

 Ovaria of the same number as the petals, opposite to which they are placed around an 

 imaginary axis, 1-celled, tapering into stigmata. Fruit consisting of several follicles, 

 opening by the suture in their face. Seeds attached to the margins of the suture, variable 

 in number ; embryo straight in the axis of the albumen, with the radicle pointing to the 



hilum Succulent herbs ov shrubs. Leaves entire or pinnatifid; stipidcB none. Flowers 



usually in cymes, sessile, often arranged unilaterally along the divisions of the cymes. 



Affinities. These are all remarkable for the succulent nature of their 

 stems and leaves, in which they resemble Cactess, Portulacese, and certain 

 genera of Euphorbiacese, Asclepiadeae, and Asphodelese ; but this analogy 

 goes no further. Their real affinity is probably with Saxifragese through 

 Penthorum, and with Illecebrese through Tillsea, as Decandolle has remarked. 

 In both those orders the hypogynous scales of Crassulacese are wanting. 

 Are not these bodies analogous to the scales out of which the stamens of 

 Zygophyllese spring ? If so, an unsuspected affinity exists between these 

 orders. Decandolle observes {Mcmone, p. 5.) that there is no instance of a 

 double flower in the order, although this might have been expected from 

 their analogy in structure with Caryophyllece. Sempervivum tectorum ex- 

 hibits almost constantly the singular phenomenon of anthers bearing ovules 

 instead of pollen. 



Geography. It appears, from DecandoUe's researches, that of the 272 

 species of which the order consists, 133 are found at the Cape of Good 

 Hope, 2 in South America beyond the tropics, 2 in the same country within 

 the tropics, none in the West Indies or the Mauritian Islands, 8 in Mexico, 7 

 in the United States, 12 in Siberia, 18 in the Levant, 52 in Europe, 18 in the 

 Canaries, 1 in southern Africa beyond the limits of the Cape, 9 in Barbary, 

 3 in the East Indies, 4 in China and Japan, and 2 in New Holland. They 

 are found in the driest situations, where not a blade of grass nor a particle 

 of moss can grow, on naked rocks, old walls, sandy hot plains, alter- 

 nately exposed to the heaviest dews of night and the fiercest rays of the 

 noon-day sun. Soil is to them a something to keep them stationary, rather 

 than a source of nutriment, which in these plants is conveyed by myriads 

 of mouths, invisible to the naked eye, but covering all their surface, to the 

 juicy beds of cellular tissue which lie beneath them. 



Properties. Refrigerant and abstergent properties, mixed sometimes 

 with a good deal of acridity, distinguish them. The fishermen of Madeira 

 rub their nets with the fresh leaves of Sempervivum glutinosum, by which 

 they are rendered as durable as if tanned, provided they are steeped in some 

 alkaline liquor. Malic acid exists in Sempervivum tectorum combined with 

 lime. Turner, 634. 



Examples. Sempervivum, Crassula, Cotyledon. 



