CALLITRICIACE. 119 
Svus-Srecms L—Callitriche vernalis.* Kiitz. 
Pratt MCCLXXI, 
Reich. Tc. Fl. Germ. et Helv. Vol. V. Tab. CXXIX. Fig. 4746. 
C, aquatica, Sm. Engl. Bot. No. 722. 
C. verna, Auct. Plur. Hegelm. Monogr, p. 55. 
C. pallens, Goldb. \ 
: t t. 20, 1 le 
C. cophocarpa, Sendin. est. Hegelm. 
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 depth 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 
zo inch long, and not so broad, pale yellow. Plant pale bright green. 
Vernal Water Starwort. 
French, Callitriche printaniére. German, Friihlings Wasserstern. 
The common starwort is one of the most interesting of our British water-plants. 
Tn 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 Linnean 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 function 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 Nymphea and 
Nuphar, and to the stellate cellular tissue of Juneus and other plants growing in 
water. A question has been raised as to whether they are homologous with hairs or 
* Erroneously named Callitriche eu-yerna on Plate MCCLXXI. 
