120 COLIN CLOUT'S CALENDAR. 



and similar stunted creeping meadow plants, there is 

 not much material to spare upon the leaves, and so they 

 only develop one terminal leaflet with a single pair of 

 lateral ones beneath it : in other words, they are shortened 

 into trefoils. The complementary leaflets on each stalk 

 remain always undeveloped. In these vetches, again, 

 and still more in the true peas, it is the terminal leaflets 

 that are wanting ; and in their place the end of the 

 common leaf-stalk lengthens out into twining tendrils, 

 which help the branches to creep over other plants, so as 

 to gain a decided advantage in the struggle for life over 

 the little procumbent clovers. 



Sometimes among the peas, however, circumstances 

 call for a different modification ; and then we get all 

 sorts of curious distortions or abortions, as the case may 

 demand. Thus the beautiful pink grass-pea, growing 

 among tall blades on borders of fields, requires foliage 

 like the grasses themselves, in order to compete with 

 them on terms of equality ; and it has achieved its end 

 by dwarfing the leaflets till they have disappeared al- 

 together, while at the same time the denuded leaf-stalk 

 has flattened out into a broad blade, exactly imitating 

 the grasses among which it lives. In its close relative 

 the yellow vetchling all the true leaves are reduced to a 

 long tendril ; but to make up for them the barbed stipules 

 or flaps, normally mere tags about a quarter of an inch 

 long, have grown out into a pair of expanded and heart- 

 shaped green leaves. Here we must suppose that from 

 generation to generation the original leaflets got less and 

 less work to do, and so gradually died away by mere 

 disuse ; while at the same time the leaf-stalk in the one 

 case and the stipules in the other grew larger and larger 



