Feb. 1893.] BOTANICAL SOCIETY OF EDINBUEGII, 571 



In most cases the adult form is not reached till a 

 considerable number, often four or five leaves of an 

 intermediate nature, have appeared ; and in some cases, 

 where the adult form is highly specialised, as in Ulex, 

 several distinct series of leaf-forms arise in succession 

 before the permanent condition is attained. 



Those genera, such as Vicia and Lathyrus, which have 

 hypogeal cotyledons almost always have the first leaf at least, 

 and often the first two or three, reduced to mere scale-like 

 organs, representing apparently the vagime of normal leaves, 

 since three teeth are always discernable, and all gradations 

 may be observed between the lateral teeth and the stipules of 

 the adult leaves, while the median tooth passes over gradually, 

 but not so distinctly, into the petiole of the higher form. 



In genera with epigeal cotyledons the first leaf has, in 

 many cases, a rather large lamina, which, borne on a long, 

 slender, nearly vertical petiole, projects upwards above 

 surrounding objects, and thus secures both light and air. 

 The petiole is generally provided with a sheathing vagina, 

 the margins of which are continued upwards into a pair 

 of delicate stipules, which are, however, not of exactly the 

 same shape, and not perhaps so highly specialised as those 

 attached to the adult form of leaf. 



Where the first leaf arises on an undeveloped first 

 internode within a tubular sheath formed by the union of 

 the cotyledonary vagin;e, it not unfrequently happens that 

 the thickening of the plumular bud, consequent on its 

 formation, splits the sheath along a line corresponding to 

 the median plane of the leaf, and the two cotyledons, which 

 lay at first opposite each other in a plane at right angles 

 to that containing the first leaf, are forced to converge 

 towards one another on the side opposite that from which 

 the first leaf springs. This, however, cannot occur if the 

 first internode be even slightly elongated, so as to raise 

 the first node above the vaginal sheath. 



Stem. — The aerial stem in most of the British 

 Leguminosaa is annual, dying down in autumn to the 

 level of the ground, and being replaced in spring, if the 

 plant persists for more than one year, by a larger or 

 smaller number of lateral branches, which arise from the 

 subterranean part of the stem. 



