172 



PEINCIPLES OF PLANT-TERATOLOGY. 



of that above-mentioned in the purple clover would 

 not modify the imparipinnate character of the leaf. 



In various species of Frag aria and Potentilla the 

 leaves of the epicalyx or calyculus, representing, 

 according to the usual view, the stipules of the sepals 

 fused in pairs, may become divided and the original 

 ten stipules restored. The stipular theory seems 

 proved by an observation made by Velenovsky in 

 flowers of Fragaria vesca in which some of the sepals 

 appeared as simple green foliage-leaves and the 

 divided calyculus clearly as stipules. Domin observed 



a c 



(0»o} h 



Fig. 48. — Carpinus Betulus. a. Normal compound bract. 6. Its dia- 

 gram, c. Bracteoles dissociated from bract, d. Diagram of same. 

 (After Celakovsky.) br, bract ; br 1 and br 2 , bracteoles. 



in Potentilla canescens small foliar organs similar to 

 the calyculus-leaves occurring scattered to the number 

 of two or three, on or immediately below the recep- 

 tacle ; in P. verna he occasionally saw a leaf of the 

 epicalyx developed as a foliage-leaf ; which facts lead 

 him to think that the calyculus may represent five 

 bracts which have been carried up from below ; but 

 they are probably consistent with the former view. 



In the madders (Rubia peregrina and B. tinctorum) 

 and the crosswort {Galium Gruciata) the usually fused 

 stipules may become divided, thus yielding, instead of 

 four, six leaves in a whorl. 



Velenovsky observed in Salix the splitting of the 

 median gland of the flower into two, representing the 

 reproduction of the ancestral pair of bracteoles (fig. 43, 

 p. 160). 



