KEY. 269 



Perianth greenish, the 3 inner sepals larger, some- 

 what colored. Flowers small, in slender, panicled racemes, 

 Avhich on the fertile plant become reddish in summer. Sta- 

 mens 6. Rumex Acetosella, L. 



885, Filaments of the sterile flowers united into a solid 

 column ; anthers 6-12, linear. Ovary of the fertile flowers 

 6- to 9-celled ; stigmas 6-9. Sterile' spathe l-leaved, with 

 about 3 long-peduncled flowers ; the fertile 2-leaved, with a 

 solitary, short-peduncled flower. Leaves round-heart-shaped, 

 long-petioled, spongy-reticulated and purplish beneath. 



Ijimnobiiiin Spongia, Rich. 



Filaments not united, or scarcely any. Ovary 1- 



celled, with 3 parietal placentae. Stigmas 3. Leaves linear, 



or oval-oblong 886 



886, Stems leafy and elongated. Both sorts of flowers 

 solitary and sessile, from a sessile and tubular, 2-cleft 

 spathe. Sterile flowers small or minute, with 3 sepals, as 

 many narrower petals, and 9 sessile anthers. Fertile flowers 

 with a tubular, exceedingly long and thread-form, 6-lobed, 

 colored perianth, and 3-6 antherless filaments, the tube rising 

 to the surface of the water, to be fertilized by the sterile 

 flowers, which break off under water and then float on its 

 surface. Leaves linear, or oval-oblong, whorled or opposite. 



(707) Anacharis Canadensis, Planch. 

 Stems none. Only the fertile flowers solitary. 

 Sterile ones crowded on a conical spadix in a 3 -parted 

 spathe, which is borne on a short scape, and consisting of a 

 3-sepalled calyx only and 3 stamens ; they break away and 

 rise to the surface of the water, to fertilize the pistillate 

 flowers. The latter have a 3-lobed calyx-tube, which is not 

 extended beyond the elongated ovary, and 3 linear, small 

 petals ; they are sessile in a tubular, bifid spathe, borne on 

 an exceedingly long, peduncle-like scape. The latter coils up 

 spirally, to draw the fertilized ovary under water, to ripen. 

 Leaves linear, thin, long and ribbon-like. 



Vallisneria spiralis, L. 

 {Eel-grass.) 



887, (876.) Flowers (at least the sterile) with a regular 

 perianth of 3 to 6 segments or sepals 888 



Flowers naked (the sterile, in one genus, in a little, 

 coAvl-shaped spathe), or glumaceous 902 



