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OBSERVATIONS ON RANUNCULUS FICARIA. 



MARY A. JOHNSTONE, B.Sc, F.L.S. 



One of the most curious features of the morphology of the 

 Lesser Celandine (Ranunculus Ficaria) is the duplicated 

 grouping of tuberous roots, a duplication, the occurrence of 

 which is limited to certain plants. 



The simpler type of plant possesses only the underground 

 tuberous organs. Below ground it consists of a much abbre- 

 viated stem region, a few ordinary absorptive roots and a 

 crowded cluster of pear-shaped storage roots, together with, 

 at certain times, the remains of the tubers of the previous 

 season. From the top of the buried stem arise one or more 

 branching aerial stems, bearing scale and foliage leaves ; a 

 varying number of radical leaves may also spring from the 

 same region ; flowers are borne apparently terminally on the 

 branches. 



In the more complicated plant, additional tuberous bodies 

 arise in the axils of the cauline leaves ; these also are modified 

 roots. When present at all, they occur in the axil of every leaf , 

 the number at any level varying from one to about nine. When 

 the plant dies down in June, the tubers, together with the 

 minute bud to which they are attached, drop to the ground 

 along with the decaying, leaf age. There they may develop as 

 independent plants, and thev thus constitute a well-known 

 example of vegetative reproduction. They are interesting in 

 many ways, but the only point upon which I wish to touch 

 now is the relationship of the plants that bear them to those 

 of the first group, and the relationship of both to their 

 surroundings. 



The commonly accepted theory is that plants bearing 

 aerial tubers are restricted in their occurrence to deeply shaded 

 situations, from which flower -bearing plants are in their turn 

 absent. The absence of flowers is considered to be correlated 

 with the infrequency of insect visits in such quarters, re- 

 production being provided for by the vegetative structures 

 in the leaf axils. Whilst acknowledging the existence of 

 of a sufficient amount of evidence to account for such a 

 generalisation having been put forward, I think, after comparing 

 together a very large number of habitats, that the explanation 

 does not account for the actual distribution of the plants, 

 and I should like to record a few out of many instances where 

 I have considered it to fail. 



A word first about those specimens which bear aerial 

 tubers. The most significant distinguishing characteristic is 

 the great reduction in the number of flowers produced, and in the 

 number of carpels on these few flowers ; in some colonies, 



1917 Mar. 1.2 



