382 



LXXX. URTICACE^. 



bicuspidate above the base, 1 -celled, with one pendulous ovul 

 Style oblique, filiform, at length hardened, persistent. StioJ,' 



EiiibrijQ 



simple. Fruit an. acJiene, 1 -seeded. Albumen 0. _,„^^ 

 straiolit ; with 2 cotyledons and a many-leaved plumule ; radicl 

 inferior. — An aquatic Order comprising one genus of douhtful 

 affinity. Leaves whorled^ rigid, dichotoinous, with narrow $er. 

 rated segments. 



1. Ceratophyllum Linn. Ilornwort. 



Character same as of the Order. — JTame : icspag^ tceparoc a 

 7tora, and (pvXXov^ a leaf, from the forked leaves. ' 



1. C. demersmn L. (common H,) ; fruit armed with 2 spines 

 or tubercles near the base and terminated by the longish subu- 

 late style. — a. spines of the fruit rigid long terete. £. £ 

 t, 947. C. oxyacanthum Cham. — /3. * spines of the fruit Ion ' 

 rigid laterally compressed and winged at the base. C. platv^ 

 canthum Cham. **'"-- - ■• ^ "■ ■' - - - . r J 



no spines. 



0' 



■y. *two tubercles at the base of the fruit and 

 C. submersum DC. C. apiculatum Cham. 



Frequent in slow streams and ditches. Ti . 7.— Floating. Stem 

 long, slender. Leaves setaceous, whorled, 2 or 3 times forked, dis- 

 tantly serrate. Flowers small, whorled in the axils of the leaves. 

 Spmes of the//'MzY sometimes very obscure. The foliage of this plant 

 IS often inflated and jointed, so as to look like a Conferva. Smith 

 remarks that he observed the segments of the perianth to be always 

 emarginate or bifid in this species, and entire in C. suhmersum; but'it 

 would appear from Lindley's Veget, Kingd. p. 263. fig. 178, that 

 no dependence can be placed on this. Our var. a. is the most common 

 m this country ; p. is the most common in Germany, and both it 

 and y. may have been passed over with us as the same as a. The 

 vaK y. forms a link between this and the next. 



2. a suhmersum L. (unarmed H.) ; fruit without spines or 

 tubercles and termmated by the very short style. E B. t. 679 

 C. muticum Cham. 



Ditches in the east and south of England, rare. T^ . 6, 7 — Only 

 to be distinguished from the preceding by the very short persistent 

 style (much shorter than the fruit), and the total absence of either 

 spmes or tubercles. 



1 tac- 



con 



I Inin 



Hii 



I 



m 



km 



Orb. LXXX. UETICACE^ Juss. 



Flowers generally monccclous or diceclous (very rarely some 

 of them perfect), scattered, or amentaceous, or a-gre-ated, on a 

 fleshy persistant receptacle. Perianth dividedf persistent or 



wanting. Stamens definite, distinct, opposite the lobes of tbe 



