A NGIOSPERMS : TRILLIUM. 



321 



present the only suggestion which it gives of belonging to the 



leaf series is the fact that the end is divided into three parts, the 



number of parts in each successive whorl of members of the 



flower. If we cut across the body of this pistil and examine it 



with a low power we see that there are three chambers or cavi- 



ties, and at the junction of each 



the walls suggest to us that this 



body may have been formed by the 



infolding of the margins of three 



leaf-like members, the places of 



contact having then become grown 



together. We see also that from 



the incurved 



margins of each 



division of the 



pistil there stand 



out in the cavity oval bodies. 



These are the ovules. Now the 



ovules we have learned from our 



study of the gymnosperms are the 



sporangia (here the macrosporangia). 



It is now more evident that this curious body, the pistil, is made up 



of three leaf-like members which have fused together, each mem- 



ber being the equivalent of a sporophyll (here the macrosporo- 

 phyll) . This must be a fascinating observation, that 

 plants of such widely different groups and of such 

 different grades of complexity should have members 

 formed on the same plan and belonging to the same 

 series of members, devoted to similar functions, and 

 yet carried out with such great modifications that at 

 first we do not see this common meeting ground 

 which a comparative study brings out so clearly. 



645. Transformations of the flower of trillium. 

 If anything more were needed to make it clear that 

 the ^^ of the flower o f tr ini um belong to the leaf 



fig. 382. 

 S caLTofTrii d 



the margin. 



series we could obtain evidence from the transformations which 



