2.34 NOTES ON THE TEASELS, DIPSACUS SYI.VESTKIS AND 



Teasel " even the tips of the awns of the flowering head have this 

 downward inchnation. 



It is not easy to say what are the foes so carefully guarded 

 against. That there are, or have been, foes in the case of the cups 

 there can be no doubt; for the most careful observation will not 

 show that the water is in any case absorbed by the plant, or used as 

 nourishment. 



Ants have been suggested as possible enemies, but it is hard to 

 see what harm they could do. The prickles in any case are not 

 against them. In the allied species, D. piiosus, the cup is represented 

 by a fringe of bristly hairs, which also is no protection against ants. 

 Slugs and snails in both species are guarded against ; but far more 

 effectively in D. sylvestris, although there is reason to believe that 

 no English species of MoUusca now attack the plants. 



It does not seem that the prickly apparatus is directed against 

 the attacks of cattle, as these prickles are rarely hardened enough to 

 cause much inconvenience till the plant has flowered, when the 

 foliage will be dry and tasteless. 



It may be that the prickles at an early stage guard against 

 molluscs^ and at the last stage assist in dissemination of the seed- 

 heads by attaching themselves to the wool of cattle, &c. 



We will now attempt to trace the mutual relationship of the two 

 species. 



When we consider that D. piiosus has only the rudiments of a 

 prickly system, and a rudimentary form of cup, we infer, either that it 

 is a degenerate form of D. syhestris, or, on the other hand, is more 

 nearly allied to an ancestral form. An examination into the struc- 

 ture and habits of both species will show that the latter alternative 

 must probably be the one accepted. 



In plants of the first year it is hardly possible to discriminate 

 the species, both being so much alike. The configuration of the 

 leaf in this early stage is instructive, the limb is reduced to a rudi- 

 mentary fringe for nearly half the length of the mid-rib, and the 

 leaves may therefore be regarded as petioled. There is a tendency 

 to development of the sheath of the petiole equally in both species. 

 The epidermis is also here equally active, giving rise to occasional 

 prickles, and develops the serrature on the mid-ribs of the leaves of 

 both. 



The start in the following spring appears to run for a short time on 

 equal lines, as the radical leaves are much alike ; but a difference soon 



