RIVER-WEED FAMILY. 



205 



Family 43. PODOSTEMACEAE Lindl. Nat. Syst. Ed. 2, 190. 1836. 



RIVER- WEED FAMILY. 



Small aquatic fresh-water mostly annual fleshy herbs, the leaves usually poorly 



llerentiated from the stem, the whole structure commonly resembling the thallus 



an alga or hepatic, the small usually perfect flowers devoid of any perianth and 



Intended by a spathe-like involucre, or in some genera with a 3-5-cleft mem- 



:.mous calyx. Stamens hypogynous, only 2 in the following genus, numerous in 



'.ne others; filaments united or distinct; anthers 2-celled, the sacs longitudinally 



hiscent. Ovary stalked or sessile, 2~3-celled ; ovules usually numerous in each 



. ;1, anatropous ; styles 2 or 3, short. Capsules 2-3-celled, ribbed. Seeds numer- 



s, minute, without endosperm ; embryo straight. 



About 21 genera and 175 species, mostly in the tropics, only the following North American. 



i. PODOSTEMUM Michx. Fl. Bor. Am. 2: 164. pi 44. 1803. 



Habit of the several species various. Flowers sessile or very nearly so in the spathe-like 

 i olucre. Perianth none. Stamens 2, their filaments united to near the summit ; anthers 2, 

 long or oval. Staminodia 2, filiform. Ovary ovoid, 2-celled; stigmas 2, nearly erect, short, 

 bulate. Capsule ovoid, 6-io-ribbed, 2-valved. [Greek, stalked-stamens.] 



About 12 species of rather wide geographic distribution, the following typical. Besides the 

 lowing, another occurs in the southern United States. 



Podostemum ceratophyllum Michx. River- 

 weed. Thread- foot. Fig. 2130. 



dosiemum ceratophyllum Michx. Fl. Bor. Am. 2 : 165. 

 1803. 



Plant dark green, rather stiff, firmly attached to 

 >nes in running water, densely tufted, i'-io' long, 

 e leaves narrowly linear, sheathing at the base, 

 mmonly split above into almost filiform segments 



lobes. Flowers less than i" broad, at length 

 ;rsting from the spathes; capsule oblong-oval, 

 .ther more than i" long, obtuse, borne on a stipe 



about its own length, 8-ribbed; stigmas at length 

 curved. 



Firmly attached to stones in shallow streams, New 

 runswick to Ontario and Minnesota, south to Georgia, 

 abama and Kentucky. July-Sept. 



Family 44. CRASSULACEAE DC. Fl. Franc. 4: 382. 1805. 



ORPINE FAMILY. 



Herbs, or somewhat shrubby plants, mostly fleshy or succulent, with cymose 

 ' rarely solitary regular or symmetrical flowers. Stipules none. Calyx per- 

 stent, free from the ovary or ovaries, mostly 4~5-cleft or 4-5-parted. Petals 

 lual in number to the calyx-lobes, distinct, or more or less united, usually per- 

 stent, rarely wanting. Stamens of the same number or twice as many as the 

 etals ; filaments filiform or subulate ; anthers longitudinally dehiscent. Receptacle 

 ith a scale at the base of each carpel. Carpels equal in number to the sepals, 

 -tinct, or united below ; styles subulate or filiform ; ovules numerous, arranged 

 2 rows along the ventral suture. Follicles membranous or coriaceous, i-celled, 

 hiscent along the ventral suture. Seeds minute; endosperm fleshy; embryo 

 'rete ; cotyledons short, obtuse. 



About 30 genera and 600 species, of wide geographic distribution. 



