. OALLITEICHIKE^. 463 



there is no perianth, and they are therefore more frequently enumerated 

 amongst anomalous MonocMamyds. * 



I. CSRATOPIIVI.I.. CERATOPHYLLTTM. 



Leaves whorled and dissected. Stamens several. Style 1. Ovary and 

 fruit entire, with a single seed. 



1. Common Ceratopbyll. Ceratopliylluin demersum, Linn. 



(Eng. Bot. t. 947, and C. stibmersum, t. 679. Hormoort.) 

 A glabrous pei-ennial, the stems floating like those of a 3Iyriophyll, and 

 the leaves are whorled in the same manner, but instead of being pinnately 

 divided they are twice or thrice forked, with linear, often fine and subulate 

 segments, usually slightly toothed on the edge. Flowers small, and sessile 

 in the axUs of tlie leaves, each one surrounded by a whorl of minute bracts, 

 but without any real perianth ; the males consisting of 12 to 20, sessile, ob- 

 long anthers, the females of a small ovary with a simple style. Fruit an 

 ovoid, slightly compressed nut, 2 to 3 lines long, either smooth or with a 

 few tubercles or prickles, either scattered over the surface or imited in a 

 slightly prominent wing round the edge. 



In pools, slow streams, and shallow margins of lakes, dispersed almost 

 all over the globe. Not uncommon in Britain. Fl. summer, hut very seldom. 



II. CALLITRXCHE. CALLITEICHE. 



Leaves opposite, entire. Stamens solitary. Styles 2. Ovary and fruit 

 4-lobed and 4-seeded. 



1. Common Callitriclie. Callitriche aquatica, Sm. 



(Eng. Bot. t. 722, and C. autumnalis, Suppl. t. 2606 and t. 2732. C. pe- 

 diinculata, Brit. Fl. C. platycarpa, Bab. Man.) 



A glabrous, slender perennial, either floating in water or creeping and 

 rooting in wet mud, flowering young so as to appear annual, varying in 

 length according to the depth of the water. Leaves either all obovate or 

 oblong, 1 to 6 lilies long, or the lower submerged ones narrow-linear, and 

 obtuse or notched at the top; the upper ones obovate, and spreading in httie 

 tufts on the surface of the water, or all submerged and linear. Flowers 

 minute, usually solitary in each axil, between 2 minute bracts varying much 

 in size and sometimes wholly wanting. Male flowers consisting of a smgle 

 stamen with a conspicuous filament ; the females of a sessile or stalked ovary, 

 with 2 erect or recurved styles. Fruit from ^ to 1 line in diameter, the 

 lobes either rounded or keeled on the edge, or surrounded by a narrow 

 wing. 



In shallow waters or wet mud, dispersed almost all over the globe. Abun- 

 dant in Britain. Fl. the toJiole season. It has been variously divided into 

 from 2 to about 20 supposed species, from slight differences in the size and 

 form of the fruits, the direction of the styles, in the bracts, etc., or from the 

 presence or absence of the upper obovate leaves; but the distinctive cha- 

 racters which have been given, all fail when apphed to a large number of 

 specimens collected in different parts of the world. 



