480 



NATURAL HISTORY OF PLANTS. 



Ceratophylium vulgare (submersum). 



ing a multifid perianth. 1 Inside this we find the indefinite stamens, 

 each formed of a snbsessile extrorse anther, dehiscing more or 

 less completely by longitudinal clefts 2 (fig. 527). The females 

 (figs. 531, 532) have the same receptacle and perianth; and the 

 gynajceum consists of a free one-celled ovary tapering above into a 



long subulate style, undilated at 

 its stigmatiferous apex. 3 Within 

 the ovary and near its apex is 

 a placenta bearing a suspended 

 orthotropous ovule with its micro- 

 pyle inferior. As the ovary grows 

 two or three little points develop 

 near its base, which enlarge and 

 harden greatly in the fruit of 

 Long. sect, of female certain varieties 4 (figs. 528, 529). 

 flower. The fruit is an achene, 5 containing 



a suspended orthotropous seed, with 

 very thin coats and a large exalbuminous embryo. This is well- 

 developed, a complete plant in miniature ; 6 its short radicle is 

 inferior ; and the axis bears first the two large opposite cotyledons, 

 and then a pretty large number of leaves, arranged like those on 

 the stem, 7 and often possessing axillary buds. 9 Ceratojjliyllam com- 

 prises perennial aquatic herbs, submerged-natant, abundant in the 

 fresh waters of Europe, North America, and the Antilles. Their 

 branches are herbaceous, long and slender, covered with rigid brittle 

 verticillate leaves, once or repeatedly di- or trichotomous, multifid 



Fig. 531. 

 Female flower (f). 



Fig. 532. 



iii. 254, t. 297. — DC, Prodr., iii. 73. — Nees jttn., 

 Gen., viii. 1. 11.— Endl., Gen., n. 1829. — Liitol., 

 Veg. Kingd., 263, fig. 178. — Schleid., in Lin- 

 ncea, xi. 513, 1. 11. — C. J. DE Coedem., in Adan- 

 sonia, iii. 292. — Lem. & Dcne., Tr. Gen., 505. — 

 Hydroceratopliyllum Vaill., in Act. Ac. Par. 

 (1719), t. 2, fig. 2. — Dichotophgllum Dillen., 

 Gen., 91, t. 3. 



1 Its divisions are equal or unequal. 



2 The clefts may be well defined or irregular, 

 or else of tardy occurrence. The apex of the 

 connective is prolonged into one or two points 

 above the cells. 



3 It is papillose on one side. 



4 Especially C. demersum L. (-Spec , 1409). — 

 C. cornidum Rich. (Anal. Fr., 46, 93) ; while in 

 C. submersum L., it is said that the prickles are 



quite absent. This is true of the flower in general, 

 even where they are present and attain to a more 

 or less notable development in the fruit. 



5 It is finally quite dry, but is really rather a 

 drupe, with a very bard stone and a very thin 

 exocarp, covered with little warty dots. 



6 Its development was first studied in 1827 by 

 Ad. Beongniaet (in Ann. Sc. Nat., ser. 1, xii. 

 251, t. 44, fig. B). 



7 The first pair above the cotyledons are usually 

 simple, and were described by Nees as a third 

 and fourth cotyledon. 



8 C. J. de Coedem., loc. cil., 293. A trace of 

 mucous albumen is often found between the folds 

 of the embryo. Above, the seed bears a little 

 brown chalazal cupule, much thicker than the 

 rest of the seed-coats. 



