] 50 BOTANY. 



attached to the placentas by long thread-like funiculi ; spermoderm gelatinous 

 extex'nally ; albumen horny ; embryo straight, minute ; radicle pointing to 

 the hilum. Shrubs with alternate lobed leaves, having a plicate vernation. 

 They are natives of temperate regions, and are found in Europe, Asia, and 

 America. Many yield edible fruits, which sometimes contain malic acid. 

 The various kinds of Gooseberry (Rihes grossularia) , and Currant {Ribes 

 rubrum and nigrum) belong to this order. It contains two or three genera, 

 and nearly one hundred species. Examples : Ribes, Robsonia. The 

 family is represented in North America by the genus Ribes with twenty- 

 eight species. 



Order 131. Cactace^e, the Cactus Family. Sepals numerous, usually 

 % and confounded with the petals ; adherent to the ovary. Petals numerous, 

 usually indefinite, sometimes irregular, inserted at the orifice of the calyx. 

 Stamens indefinite, cohering more or less with the petals and sepals ; 

 filaments long, filiform ; anthers ovate, versatile. Ovary fleshy, inferior, 

 unilocular; style filiform ; stigmas numerous; ovules », attached to parietal 

 placentas equal in number to the stigmas. Fruit succulent, one-celled. 

 Seeds «=, parietal, or, after losing their adhesion to the placenta, nestling in 

 pulp, ovate or obovate ; albumen ; embryo straight, curved, or spiral ; 

 cotyledons thick, leafy, sometimes nearly obsolete ; radicle thick, obtuse, 

 next the hilum. Succulent shrubs, with peculiar angular or flattened stems, 

 having the woody matter often arranged in wedges. Leaves usually 

 absent ; when present, fleshy, smooth, entire, or spinous. Flowers sessile, 

 sometimes showy. They grow in hot, dry, and exposed places, and are 

 natives chiefly of the tropical parts of America. Some grow rapidly on the 

 lava in volcanic countries. There are sixteen known genera, and about 

 eight hundred species. Examples : *Opuntia, *Mammillaria, *Echinocactus, 

 *Cereus, &c. These genera, with numerous species, represent the order in 

 (extra-Mexican) North America. 



The plants of this order are remarkable for their succulence, for the great 

 development of their cellular tissue, and for the anomalous forms of their 

 stems, which sometimes are of great size. Opuntia vulgaris or prickly 

 pear yields an agreeable fruit. The Night Blooming Cereus (Cereus 

 grandiflorus) expands its large fragrant flowers only about ten p.m., which 

 become withered before morning. 



Cereus hexagonus {pi. 69, ßg. 3) ; b, spines magnified. 



Order 132. Ficoide/e or MESEMBRVANTHACEiE, the Ficoid or Mesem- 

 bryanthemum Family. Sepals definite, usually five, but varying from four to 

 eight, more or less combined at the base, adherent to the ovary or distinct 

 from it, equal or unequal; aestivation valvate or imbricate. Petals indefinite, 

 colored, sometimes 0. Stamens perigynous, distinct, definite, or indefinite ; 

 anthers oblong, incumbent. Ovary usually plurilocular ; stigmas several, 

 distinct ; ovules 00, anatropal or- amphitropal, attached by cords to the 

 placenta, which is either central or parietal. Fruit a many-celled capsule, 

 opening in a stellate or circumscissile manner at the apex, or an indehiscent 

 nut. Seeds 00, rarely definite or even solitary ; embryo curved or spiral 

 on the outside of mealy albumen ; radicle next the hilum. Herbaceous oi 

 150 



