OF THE GENUS ULEX. 41 



Seedlings were also observed of the second year's growth, 

 growing under the same conditions, with more than one hundred 

 trifoliate and difoliate leaves. 



These observations are not only interesting as showing the 

 very considerable variation existing among seedlings of Ulex^ but, 

 as I have already mentioned, afford some evidence of the effect of 

 the environment upon the production of the spiny character; 

 those seedHngs which were grown upon humus soil having begun 

 to develop the spiny character much later than those grown upon 

 the stony loam. 



The primary axis of a seedling stops growing, according to 

 Buchenau, at the end of the first year. In all the seedlings which 

 he examined at this stage, he found that the tips were dead, and 

 the same thing was repeated on the side-shoots. He supposes 

 that the young buds at the apex get killed by the frost. My own 

 observations show that this is not so, however. In many seedlings 

 I have found that both the main axis and the lateral shoots con- 

 tinue to grow a second year, but very rarely for a third year. It 

 is probable, however, that it is only during a fairly mild winter — 

 such as that of 1895-6 — that any considerable number of apical 

 buds escape destruction. 



The trilobed form of the primary leaves in seedlings of Ulex 

 is compared by Buchenau to that observed in seedlings of Cytisus ; 

 and Winkler also has a paper on the comparison of the two seed- 

 lings. According to these observers — and, generally, my own 

 observations agree with theirs — the seedlings of Cytisus develop 

 four- to six-stalked trifoliate leaves, the first few pairs being in pairs 

 and opposite to each other, and the others arranged spirally. But, 

 just as in Ulex^ this development varies. Spathulate leaves are 

 sometimes first developed, then trifoliate ones, and these again 

 may suddenly or gradually pass over into the spathulate form. 

 There is no reduction of the leaves to spines. It is interesting, 

 also, to compare the adult plant of Cytisus with that of Ulex. In 

 the former the lower leaves on a branch are stalked and trifoliate ; 

 the upper ones are sessile and often reduced to a single leaflet. 

 The simple leaves are produced, as in Ulex, by the loss of, first, 

 one lateral leaflet, then the other. Ulex differs from Cytisus only 

 in the fact that trifoliate leaves are formed much less frequently, 



