CALLITRICHACE7E. 1 1 9 



Sub-Species I.— Callitriche vernalis.* Kntz. 



Plate MCCLXXI. 



Reich. Ic. Fl. Germ, ct Helv. Vol. V. Tab. CXXIX. Fig. 4746. 



C. aquatica, Sm. Engl. Bot. No. 722. 



C. vcrna, Auct. Plur. Hegclm. Monogr. p. 55. 



C. pallcns, Goldh. 1 , , tt 7 



r^ , n ■, ( "^"^st. liertelm. 



U. cojjuocarpa, bcudtu. J 



Pollen grains elliptical. Fruit sessile, longer than broad, subcordate, 

 convex on the faces ; marginal furrows shallow ; margins of the lobes 

 shortly and sharply keeled ; styles erect or spreading, subpersistent. 



In ditches and ponds or in mud. Common, and generally distributed. 



England, Scotland, Ireland. Perennial. Early Spring to Autumn. 



Stems round, slender, varying in length according to the dejDth of 

 the water in which the plant grows. Leaves when submerged mostly 

 linear ; when growing out of the water, obovate ; but even when im- 

 mersed a few of the upper leaves are larger (^ to 1 inch long), obovate, 

 and with the internodes between them very short, so as to form a 

 floating rosette. Flowers in the axils of the leaves ; often there is a 

 female flower on one side of the stem, and a male one opposite to it. 

 Each flower with 2 white membranous strapshaped incurved deci- 

 duous bracts at the base. Filament at length very long. Fruit about 

 2V hich long, and not so broad, pale yellow. Plant pale bright green. 



Vernal Water Starwort. 



Frencli, Callitriche printaniere. German, Frilhlings Wasserstern. 



The comm.011 starwort is one of the most interesting of our British water-plants. 

 In the early spring, and even in the winter, its bright green stellate leaves are 

 striking objects in deep ditches and ponds. The under surface of these leaves is 

 studded with numerous gland- like bodies having a circular rosette form. They can be 

 easily seen by the low powers of the microscope, but are not visible to the naked eye, 

 giving only a whitish glistening aspect to the under surface of the leaves. They were 

 first described by Dr. Lankester at a meeting of the British Association held in 

 Edinburgh in 1850, and afterwards in the proceedings of the Linnaean Society. 

 These gland- like bodies consist of from four to eight distinct cells surrounding a cen- 

 tral cell, which is attached to the cellular tissue of the leaf below. At first these little 

 cells are filled with fluid, but as the plant gets older, and the period of inflorescence 

 arrives, they are filled with air. The fonction performed by these little bodies is 

 undoubtedly that of lightening the leaf, and thus enabling the whole plant to lift itself 

 in the water. In this respect their function is analogous to the vesicles found in 

 Utricularia, and to the intercellular spaces found in the leaves of Nymphcea and 

 Nuphar, and to the stellate cellular tissue of Junctis and other plants growing in 

 water. A question has been raised as to whether they are homologous with hairs or 



* En-oneously named Callitriche eu-verna on Plate MCCLXXI. 



