73. CERATOPHYLLACE.E. 74. CALLITRICHACE^E. 293 



Order LXXIII. CERATOPHYLLACE.E. 



Fl. monoecious. Perianth free, in many divisions. Anth. 12 

 20, sessile, 2-celled, 2-pointed ; cells again partially divided. 

 Perigone none. Ovary 1-celled. Seed 1, pendulous. Embryo 

 straight ; cotyledons 4, alternately smaller. Only one genus/ 



1. CERATOPHYLLUM Linn. Hornwort. 



1. C. demersum (L.); segments of 1. linear-filiform, fr. not 

 winged with a spine on each side near the base and tipped with 

 the curved subulate style. E. B. 947. L. 2 4 times forked, 

 dark green; segments of uppermost 1. broader and more rigid. 

 Ponds and ditches. P. VI, VII. 



2. C. submersion (L.) ; segments of 1. setaceous, fr. destitute 

 of spines covered with cylindrical tubercles and tipped with the 

 short curved style. E. B. 6/9. L. pale green. Young fr. 

 smooth. Ponds and ditches. P. VI. VII. 



Order LXXIV. CALLITRICHACE^. 



Fl. mostly monoecious, solitary, minute, usually with 2 white 

 bracts, no perianth. Stam. 1. Filament long. Anth. reniform, 

 I -celled, opening transversely at the top. Perigone none. Ovary 

 1, 4-angled, 4-celled. Styles 2, subulate. Fr. dry, 4-celled, 4- 

 lobed: separating into 4, 1 -seeded, indehiscent carpels. Em- 

 bryo in axis of fleshy albumen. Radicle superior, long. Coty- 

 ledons short, terete. Only one genus. 



1. CALLITRICHE Linn. Water Starwort. 



1. C. verna (L.) ; fr. nearly sessile, lobes parallel in pairs 

 bluntly keeled on the back, styles erect deciduous, bracts falcate. 

 E. B. 722. E. v. 129. Lower 1. linear; floating 1. ovate-spa- 

 thulate, in a rosette, rarely wanting. Fr. small ; keels of each 

 pair of lobes converging. Bracts falling short of fruit. Common 

 in stagnant and slowly running water. A. or P. IV. IX. 



2. C. platycarpa (Kiitz.) ; fr. nearly sessile, lobes parallel in 

 pairs slightly winged on the back, styles erect in flower persistent 

 and refl'exed closely with fruit, bracts falcate.^. B. S. 2864. 

 R. v. 129. Lower I. of st. and branches linear; floating 1. round- 

 obovate-spathulate, in a close rosette, often wanting. Fr. twice 

 as large as that of C. verna, pale when dry. [/3. C. stagnalis 

 (Scop.) ; lobes of fr. more spreading, /. all round obovate-spa- 

 thulate.'] Common, especially on mud. A. or P. V. IX. 



3. C. peduneulata (DC.) ; fr. stalked or nearly sessile, lobes 



