34 



BRITISH FLOWERING PLANTS 



The first leaves or "cotyledons" generally differ 

 very much from the leaves which follow. Klebs — 

 writing as lately as 1884 — refers to these difierences, 

 and expressly says that they are " an enigma." I have 



suggested^ as an explanation 

 that the cotyledon develops 

 iu the seed, and the leaf 

 in the bud, and that the 

 conditions of the two are 

 very different. 



In the same work I have 

 vs in a variety of cases en- 

 deavoured to indicate the 

 reasons for the various forms 

 assumed. Fig. 18, which 

 represents the seedling of 

 the Horned Poppy, may be 

 taken as a typical case 

 showing the gradual passage 

 from the simple filiform 

 cotyledon to the fully de- 

 veloped leaves. In other 

 cases the cotyledons them- 



Fio.l8.—Glaudwncorniculatum. Seed- SelveS are mOre COmplcX. 



ling. (Nat. size.) c, cotyledon ; 1-7, Examoles are mentioned, 



successive leaves. ^ -in 



and reasons suggested for 

 the differences under the Violet, Eadish, Geranium, 

 Lime, Oak. 



The Stem 



There are two ways in which a prostrate, stemless 

 plant may raise itself into the light and air. One would 

 be by bending itself round so as to form a tube (Fig. 19). 

 We can imitate this by a sheet of paper, which is much 

 less pliable and more rigid if rolled up. In such cases 

 the opposite edges will often unite, or, in botanical 

 language, will become adnate, at any rate below, often 

 remaining free above. Of such a growth an ordinary 



^ Avebury (Lubbock), A Contribution to our Knowledge of Seedlings. 



