FROG-BIT TRIBE a&9 



Class II 



MONOCOTYLEDONOUS PLANTS 



In the plants belonging to this class the embryo of the seed is 

 accompanied by a single cntyledon. The stem consists of woody 

 fibre, cellular tissue, and spiral vessels ; bnt there is no true bark 

 nor pith, nor is the wood arranged in concentric layers. The stem 

 increases in density (scarcely at all in diameter) by deposits at or 

 near the centre ; hence plants of this class are called Endogenous 

 (increasing by additions on the inside). As new substance is 

 deposited, the old layers of wood are pressed outwards, and thus 

 the hardest part is near the circumference. The growth of the 

 stem is usually produced by a single terminal hud, without the aid 

 of bnds in the axils of the leaves ; there are, however, exceptions 

 to this rule, and the stem is often hollow. The principal veins of 

 the leaves are parallel, not forming a complicated network. The 

 flowers are furnished with stamens and pistils, 3, or some multiple 

 of 3, being the predominating number of the parts of fructification. 

 A large number are destitute of petals, the place of which is supplied 

 by scales or chaff (glumes). 



Sub-Class I 

 PETALOIDE^ 



Flowers furnished with petals, arranged in a circular order, or 

 without petals.* 



Natural Order LXXIX 



HYDROCHARIDACEiE.— Frog-bit Tribe 



Flower-buds enclosed in a sheath ; sepals 3, green ; petals 3 ; 

 stamens 3, 9, 12, or more ; ovary inferior, i or many-ceUed ; style i ; 

 stipnas 3-9 ; fruit dry or juicy, not bursting, i or many-celled. 

 A tribe of aquatic plants, often floating, among which the most 

 remarkable is Valisneria spiralis, the flower of which grows at the 

 extremity of a long, spiral stalk. As the bud expands the spire 

 partially uncoils, allowing the flower to fl®at on the surface for a 

 few hours, and then contract again, drawing thf seed-vessel beneath 

 the surface, there to ripen its seeds. The number of species is 



* Sub -Class II, Glumace.'e, contains plant? which have, instead of 

 petals, chaffy scales, or glumes, which are not arranged in a circular order, 

 as is the case with PetaloidecB, but are imbricated, such as the Grasses 

 or Sedges. 



