KEY. 159 



in open naked cymes (rarely in close heads, surrounded by a 

 showy, corolla-like involucre). Trees, shrubs, or herbs. 



Comus (698). 

 Fruit a pod, globular, or short and 4-sided, cubic. 

 Leaves mostly alternate, rarely opposite, lanceolate, rarely 

 ovate. Flowers axillary, yellow, or reddish. 



Ludwigia (700). 



SrS. Style 1 279 



Styles 2. Petals strap-shaped. Stamens 8, but 



only 4 of them perfect 129 



Styles 2, divergent. Petals 4 (or 5), ovate. Calyx 

 hemispherical, 4- (or 5-) toothed, somewhat adherent. Petals 

 4 (or 5). Stamens 8 (or 10). Flowers rarely all fertile, per- 

 fect, and complete. Often also marginal and radiant ones 

 present, consisting merely of a broad, rotate, 4-lobed, colored 

 calyx, lacking petals, stamens, and pistils. Pod opening by 

 a hole between the styles. Shrubs. Leaves opposite, ovate, 

 rarely cordate, pointed, serrate. Inflorescence cymose. 



Hydrajigea arborescens, L. 

 279, Ovary hemispherical or globular. Fruit a berry or a 



pod 280 



Ovary oblong or linear. Fruit a pod, 4-celled 

 (4-valved or indehiscent), rarely at length 1-celled 281 



380, Ovary hemispherical. Fruit a berry. (Oxycoccus). 



514 

 Ovary globular. Fruit a 4-celled pod, with 4 

 central, prominent placentae. Seeds many. Petals oblique, 

 inserted -svith the stamens at the summit of the 4-cleft calyx- 

 tube. Anthers oblong or linear, 1-celled, opening by termi- 

 nal pores, and sometimes spurred at the back. Leaves oppo- 

 site, 3- to 5-nerved, ovate-oblong, or lanceolate. Stem terete, 

 or square, often wdnged along the angles. Rhexia. 



381, Calyx-tube not prolonged beyond the ovary 282 



Calyx-tube prolonged beyond the ovary. Leaves 



always alternate 283 



S8S, Seeds with a large downy tuft at the apex. Leaves 



chiefly opposite, at least the lower ones, or scattered. Pod 



linear. Flowers violet, purple, or white. £pilobiiiui. 



Seeds not coniose, but naked. Leaves alternate. 



