126 MARINE ANGIOSPERMS [CH. 



remain, with their green colour masked by a layer of various 

 animal and vegetable growths. Probably the plant does not 

 attain its full development until the fifth or sixth year, and an 

 individual may live for another six years or more after reaching 

 maturity. The rhizomes are fixed in the soil by long, whitish, 

 fibrous roots, which put out a great quantity of tortuous laterals. 

 The roots form a network, which holds in its meshes the 

 gravel and mud, and thus contributes towards maintaining the 

 stability of the bed of the creek in which the plant grows. The 

 leaves, which are linear and membranous, attain the length of 

 20 to 30 cms. Fig. 84, p. 125, shows the appearance of a trans- 

 verse section of the leaf near the base of the limb. At the 

 junction of the sheath with the blade there is a ligule which 

 Bornet compares with that of the Grasses. At the extreme base 

 of each young leaf, ten ' squamulae intravaginales ' occur, and 

 the same structures are associated with the stamens and carpels. 

 The male and female flowers of Cymodocea aequorea, which 

 are borne on separate plants, and are buried 2 or 3 cms. deep 

 in the soil of the sea-shore, mature about the end of May or the 

 beginning of June. Only the stamens and styles emerge into 

 the water. The flowers are solitary, and are borne without any 

 perianth in the axils of ordinary foliage leaves. The male flower 

 consists of a pedicel bearing two stamens, completely fused as 

 to their filaments. The double nature of the stamen is revealed 

 in the single large anther of a vivid red hue, which has eight 

 pollen sacs, and is supplied by two vascular strands. The female 

 flowers are only manifested externally by white, filamentous 

 styles, which emerge in groups of four from the sheaths of 

 certain leaves. Two of these styles correspond to each of the two 

 carpels which constitute the gynaeceum. The ovary is unilocular 

 with one ovule. Until the disappearance of the pollen-mother- 

 cell, the pollen grains are roundish, but at this stage they elon- 

 gate, without increasing in diameter, until they attain the 

 dimensions of about 2 mm. by yi^- mm., thus becoming thread- 

 like. The fruits, which are ripe by August, are flat and oval 

 being roughly i cm. long by 0-5 cm. wide. The endocarp is 



