L7(J THE .lolKNAl. OF BOTANY 



preceding plankton -phase being visualized as representing a million 

 anils to a Litre 1 ,— are presented in three at first sight widely different 

 and divergent plant-series of the present world. Of these the 

 Ploridese still remain a wholly marine group, with but the slightesl 

 transmigrant extensions to fresh-water streams of the land (Batrach- 

 ospermum, Lemanea) ; Lichens, as plant-forms capable of enduring 

 the most extreme conditions of exposure and desiccation, in associa- 

 tion with their algal helots ; and thirdly the equally marvellous race 

 of the Laboulbeniaceas, holoparasitic on insects of the water and oi 

 the land. In tracing the connection of this last group of at present 

 wholly isolated fungus-types with their marine ancestors, one may 

 possibly find a further clue to the methods by which such subaerial 

 forms have been enabled to pass the period of the transmigration. 



(To be continued.) 



THE MARITIME FORMS OF MATRICARIA INODORA. 



By L. V. Lester-Oakland, M.A., F.L.S. 



It seems worth while to attempt to give an account of the 

 present state of our knowledge of the various maritime forms of 

 Matricaria inodora. There is a considerable number of them, and 

 they present a great range of variation, but the extreme forms are 

 connected by intermediates. It is hard to know what to do with 

 such a series. The variety may be the result of inter-crossing, or 

 there may be a number of " pure " races which we have so far failed 

 to discriminate. A complete account of them is impossible without 

 a prolonged study of the plants themselves in a living state, of their 

 environment, and of their response to changes of environment. 



These forms all agree in presenting certain definite points of 

 difference (though not of structural difference) from the agrestal M. 

 inodora. (a) They are biennial or perennial, not annual, (b) They 

 are more robust in habit. (c) They are more or less fleshy or 

 succulent. There are also certain features which are not common to 

 all of them, but which appear in one or more of them, but not 

 in M. inodora. (a) The fruit is larger and more fleshy. (*) The 

 flowers are often larger and the ray-florets in some cases broader. 

 (c) The margin of the phyllaries often has a brown border — light or 

 dark, narrow or deep. 



The question then arises whether it is best (1) to include them 

 all under some specific name, e. g. M. maritima, as distinct from 

 M. inodora ; or (2) to rank certain of them as varieties of M. inodora 

 (as is done by some botanists in the case of var. salina), and regard 

 the rest as specifically distinct; or ( '>! ) to regard them all as varieties 

 or forms of 21. inodora. On the whole, the last course seems to me 

 to represent the facts most closely, ami 1 suggest that the forms may 

 conveniently be grouped under three heads. 



1 ' Plankton-phase and Plankton-rate, 1 Journ. But. 1919, Supp. iii. 



