ON A GRARIA CEJE. 499 



15. lopezia Oa v.— Flowers nearly of Diplandra ; sepals 4, val- 

 vate. Petals 4, unequal, imbricate ; the 2 posterior narroAver, glan- 

 dular witMn above claw. Stamens 2, epigynous ; the anterior sterile 

 petaloid free or occasionally adnate with style and receptacle (Seme- 

 iandra) ; the posterior fertile ; filament free subulate or (Semeiandra) 

 tigWy gynandrous ; anther introrse, or more rarely subextrorse, 2- 

 rimose. Germen inferior subglobose or obconical, 4-locular, some- 

 times crowned with minute disk ; style, etc., of Diplandra. Ovules 

 in cells co , oo -seriate in internal angle. Fruit capsular subglobose, 

 from apex loculicidally 4-valvate ; valves solute from seminiferous' 

 columella. Seeds oo , obovoid (sometimes joined in pairs) ; testa 

 rugose granulate; embryo exalbuminous. — Glabrous or pubescent 

 herbs ; leaves alternate or partly opposite, petiolate, dentate ; flowers 

 in long or short racemes at top of twigs ; pedicels slender. {Mexico, 

 Guatemala.) — See p. 474. 



IV. TRAPES. 



16. Trapa L. — Flowers hermaphrodite, 4-merous ; receptacle 

 cupular, enclosing adnate base of germen (in great part free). Sepals 

 4, valvate (or lateral a little exterior), persistent, sometimes spines- 

 cent at apex. Petals 4, inserted at base of subepigynous undulate 

 or obtusely lobate disk, sessile, undulate, imbricate or more rarely 

 contorted. Stamens 4, inserted alternately with petals ; filaments 

 subulate; anthers ovately oblong introrse, 2-rimose. Germen in 

 great part free (at base only inferior) attenuated to slender style 

 capitate at stigmatose apex ; cells 2, lateral. Ovules in cells solitaryg 

 descending; micropyle introrsely superior. Fruit stipate with 

 adnate calyx and receptacle turbinate coriaceous, ligneous or sub- 

 osseous ; stipate to middle with 2-4 spinescent incrassately indurate 

 sepals and from base to apex with style, indehiscent, by abortion 1- 

 spermous. Seed large descending ; testa membranous adnate spongy 

 above ; cotyledons of incurved exalbuminous embryo unequal ; one 

 abortive minutely squamiform ; the other very large fleshy ; radicle 

 superior (in germination perforating apex of seed and fruit). — 

 Floating herbs ; rhizome elongate ; leaves 2-form ; the lower sub- 

 merged opposite rootlike piunatisect; the upper emerged floating 

 rosulate, petiole inflated spongy, limb rhomboid dentate; flowers 



32—2 



