Fetch: Notes on Aster tripolium. 



51 



{2) The prevailing form on the salt marsh Is sparingly 

 rayed, having" any number of rayed florets up to six- 

 teen (0-16) on the flowers of the same plant. In 

 many cases the rays are bent downwards and pressed 

 close to the involucre after flowering, so that they 

 are easily overlooked. Plants in which no flower 

 possesses ray florets are not so common. 



(3) Well-rayed plants with sixteen to thirty ray florets in 

 each head occur in all parts of the salt marsh, even 

 at its extreme outer edge. 



Thus, presuming that the salt marsh is the natural habitat 

 of Aster tripolium, the normal form would appear to be that 

 with a few ray florets. The plants which grow inland are the 

 representatives of a former salt marsh flora, the direct descen- 

 dants of sparingly rayed individuals which managed to survive 

 enclosure. Near the Humber they may still be found on land 

 enclosed a hundred years ago, but as a rule they disappear 

 when further reclamations place them at a greater distance from 

 the coast, and the ditches become less brackish. With their 

 more conspicuous flowers they acquire also thinner leaves^ 

 larger intercellular spaces, more chlorophyll, and a normal 

 mesophyll in place of one ' toute palisadique ' (Lesage, Influence 

 du Bord de la mer sur la Structure des Feuilles, 1890). It seems 

 to be, therefore, an instance of the well-known horticultural 

 fact that a check to vegetative growth induces the production 

 of larger flowers. The occurrence of well-ra3'ed plants on the 

 salt marsh, however, hinders the adoption of such an obvious 

 solution, but, whatever the cause, the plant advances from the 

 few to the many-rayed form, not from the rayed to the non- 

 rayed. 



Only in one place were discoid flowers found inland. These 

 grew on a small area east of Patrington Haven, which was 

 enclosed about six years ago. This is surrounded by a drain 

 inside the enclosure, about three yards from the bank, thus 

 preventing the cattle from stra3'ing on the salt marsh. In 1904, 

 constant grazing had exterminated the Aster which previously 

 grew^ on the reclaimed land ; but on the bank and on the level 

 on both sides of it the discoid form was common. 



The two 'varieties' may be gathered from the same plant. 

 On a plant which possessed thirteen main flowering shoots, 

 eleven bore discoid heads only, while the heads of the other two 

 had from o to 8 rays. Conversely those plants on which the 



1905 February i. 



