EXOGENOUS OK DICOTYLEDONOUS PLANTS. 



393 



and thickened at the apex. Fruit a one-celled capsule, opening hj 

 three valves, each bearing a parietal placenta on its middle. Seeds 

 several or numerous, anatropous, with a crustaceous integument, and 

 a straight embryo, nearly the length of the fleshy albumen (Fig. 604, 

 GO.*)). — Jflx. The Violet is the principal genus of this order; some 

 species, like the Pansy, are cultivated for the beauty of their flow- 

 ers ; others, for their delicate fragrance. The roots of all are acrid, 

 and emetic. Those of some South American species of lonidium 

 furnish a part of the Ipecacuanha of commerce. 



758. Oi'd. CistaceiB {Bock-liose Family). Low shrubby plants or 

 herbs, with simple and entire leaves (at least the lower opposite). 

 Calyx of five persistent sepals ; the three inner with a convolute 

 aestivation ; the two outer small or sometimes wanting. Corolla of 

 five, or rarely three, regular petals, convolute in aestivation in the 

 direction contrary to that of the sepals, often crumpled, usually 

 ephemeral, sometimes wanting, at least a portion of the flowers. 

 Stamens few or numerous, distinct, with short innate anthers. Fruit 



a one-c,elled capsule with parietal placentas, or imperfectly three to 

 five-celled by dissepiments arising from the middle of the valves 

 (dehiscence therefore loculicidal), and bearing the jjlacentae at or near 

 the axis. Seeds few or numerous, mostly orthotropous, with mealy 



FlG. 713. The Rock- Rose, Helianthemum Canadense. 714. Flower from Tvhich the petals 

 and stamens have fallen. -715 Magnified cross-section of the ovary ; -with a single stamen, 

 showing its hypogynous insertion. 716 Cross-section of a capsule, loculicidally dehiscent ; 

 the seeds therefore borne on the middle of each valve. 717. An ovule. 718 Plan of the 

 flower. 719. Section of a seed, showing the curved embryo. 



