460 NATURAL HISTORY OF PLANTS. 



teeth as many alternate, sometimes very small (or 0). Petals 4-8, 

 inserted in hollows, seldom large, generally small or very fugacious 

 (sometimes 0). Stamens equal in number and opposite to petals, 

 more rarely 2-verticillate and double in number, or sometimes 2, 3 ; 

 filaments more or less elongate, inserted within receptacle ; anthers 

 2-dymous, introrsely 2-rimose. Germen imbedded at bottom of 

 receptacle, free, 1-5-locular; septa sometimes evanescent; style 

 erect, slender or rather thick, enclosed or exserted, at apex stigma- 

 tose capitate subentire or obtuse. Ovules in cells oo , oftener co - 

 seriate. Fruit girt with receptacle, enclosed or exserted, capsular, 

 dehiscing septicidally or septifragally, sometimes breaking irregularly. 

 Seeds oa , small angular ; cotyledons of exalbuminous embryo thick, 

 orbicular or elliptical, often auriculate at base ; radicle short straight. 

 — Herbs generally small, sometimes creeping, oftener annual, some- 

 times aquatic ; stem oftener 4-gonal ; leaves opposite or verticillate, 

 rarely alternate, entire ; flowers small axillary, solitary or cymose or 

 glomerulate, generally few'. {All warm and temp, regions.) — See 

 p. iiO. 



22. Rhyacophila Hochst. — Flowers nearly of Ammannia, 4- 

 merous ; receptacle campanulate. Sepals 4, valvate; accessory teeth 

 as many small (or 0). Petals 4, oblong, rather large (Hydrolythrum) 

 or minute. Stamens 4 (of Ammannia). Germen 2-locular, oo -ovu- 

 late ; style short, at apex stigmatose capitate. Disk hypogynous 

 short or rather large {Hydrolythrum) unequally lobed. Capsule seeds 

 and embryo of Ammannia. — Small aquatic herbs ; leaves verticillate 

 crowded linear ; flowers in terminal racemes naked at base ; bracts 

 and bracteoles narrow or setaceous, sometimes more or less adnate 

 and raised with the flower. {India, Abyssinia.) — See p. 443. 



