136 PRINCIPLES OP PLANT-TEEATOLUGT. 



that half of each lateral sepal nearest the labellum was 

 labelliform. This phenomenon was also observed in 

 C(M.Pi/a lab lata. 



Forms of the snowdrop {Galanthus nivalis) liave 

 been seen in which all six perianth-leaves had the form 

 and coloration of the petals, due to petaloid trans- 

 formation of the usually white and larger sepals. The 

 Sachsian explanation of these cases of the orchids 

 and snowdrop, adopted by Groebel and others, is surely 

 no explanation at all; the same material which normally 

 goes to the building of a petal only has in these cases 

 also been employed for that of a sepal, hence the 

 petaloid appearance of members of the outer whorl; but 

 this proposition merely suggests the further question : 

 what has directed this inflow of petaloid material into 

 the outer whorl? and we are just where we were before ! 



Petalody of the calyx seems to indicate community 

 of origin of calyx and corolla, viz., from the androecium; 

 that petal and sepal are one and the same organ ; and 

 in this sense the phenomenon may be regarded as a 

 reversion from the more recent differentiated condition. 



Staminody. — This is much rarer. Gris records an 

 instance of a flower of the mock-orange (Pliiladeljjhits 

 speciosiis) in which one of the divisions of the calyx 

 bore an anther-loculus. A flower of the Dutch clover 

 {Trifolium refens) was seen in which one or two of the 

 semi-petaloid sepals bore anthers ; also tulips in which 

 most of the sepals had lateral lobes (of which more 

 hereafter) and one of them bore a fertile anther; 

 similarly-lobed sepals were seen in Grocus zonatus. For 

 reasons which will appear later these lobed perianth- 

 leaves of the tulip and crocus are here regarded as 

 partial, imperfect reversions to the stamens from which 

 they originally sprang. 



Magnus observed fusion of the odd sepal with the 

 " column " in the orchids Gatfleya labiata and Tricho- 

 pilia tortilis; he attributes this to the pressure caused 

 by the fused perianth- bases in the bud; but this would 

 hardly occur unless there was an innate tendency, due 



