54 



LEAVES 



being seen under the lens to be simple and unbranched. The midrib 

 is prominent on the under surface ; the majority of the lateral veins 

 leave the midrib at a rather acute angle (especially in the narrower 

 leaves) and gradually curve round towards the apex, passing into 



smaller ramifications near the 

 margin. The latter is crenate 

 or irregularly crenate- dent ate, the 

 apex blunt or subacute. Each 

 crenation terminates in a small 

 cartilaginous point which is brown 

 or black in old leaves but colour- 

 less in young ; a veinlet enters 

 each crenation and spreads like 

 a brush, a marginal veinlet ap- 

 proaching from either side, the 

 whole forming a well-marked 

 character of the foxglove leaf. 

 The odour of the fresh leaves is 

 unpleasant, and the taste of both 

 fresh and dried leaves disagreeably 

 bitter. 



Although the leaves are directed 

 to be collected from flowering 

 plants, it is not possible to dis- 

 tinguish these accurately from 

 those of the first year ; generally 

 speaking, the latter are narrower 

 and have longer petioles, whilst 

 the biennial leaves are usually 

 broader and have shorter petioles. 

 The separation is, however, not 

 material, as the first and second 

 year's leaves are about equal in 

 activity. 



FIG. 35. Foxglove leaf . Under surf ace, 

 showing the lower veins decurrent 

 in the petiole. About two-thirds 

 natural size. 



Microscopical Characters. Under epi- 

 dermis composed of cells with wavy 

 walls and smooth cuticle ; stomata 

 numerous and small ; hairs abundant 

 and of two kinds, either simple, 



uniserial, three to five or more cells, thin-walled, often warty, and frequently 

 collapsed ; or small, stalked and glandular. Midrib normal in structure and free 

 from bast or pericylic fibres. No crystals of calcium oxalate in any part of the leaf. 



The student should direct his attention particularly to 



(a) The crenate margin, 



(b) The winged petiole with decurrent veins, 





