578 



CLASS II. MONOCOTYLEDONOUS PLANTS. 



IN the plants belonging to this class the embryo of 

 the seed is accompanied by a single cotyledon. The 

 stem consists of woody fibre, cellular tissue, and spiral 

 vessels ; but 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 the 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 bud, without the aid of 

 buds 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 net-work. 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.E. 



Flowers furnished with petals, arranged in a circular 

 order, or without petals. 1 



(1) Sub-class II., GLUMACE^E, contains plants, which have, instead of 

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

 is the case with the Petaloidese, but are imbricated, such as the GRASSES and 

 SEDGES. 



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