346 



Transactions . 



P. Endlicheri is a rock-plant, living on humus lodged in rock-crevices, 

 or occurs as an epiphyte, but is never found on the ground. The roots 

 are adventitious, and form mat-like masses at the nodes. In accordance 

 with its habit, there is no need for great mechanical development, as in 

 Macropiper excelsum ; hence the root-structure is reduced. We may re- 

 gard the structure seen in the root of Peperomia Endlicheri as a reduction 

 from a type such as Macropiper excelsum (younger roots) in adaptation 

 to environment. 



Conclusions. 



Several theories have been put forward as to the origin of Monocoty- 

 ledons and Dicotyledons, and their relation to one another. One theory 

 is that Dicotyledons have come from Monocotyledons, the connection 

 being shown through the Araceae and Piperaceae ; another that Monocoty- 

 ledons have come from Dicotyledons ; and, further, that Monocotyledons 

 are diphyletic. 



The result of the present investigations on the New Zealand Piperaceae 

 has been to lead to the following conclusions concerning the Piperaceae, 

 and the relations between Mono- and Di-cotyledons : That Monocoty- 

 ledons and Dicotyledons have a common ancestry, though the point of 



Fig 



a. Seedling stem, showing slieath merging into stem ; b, passing into lowest internode of 

 seedling — 1 'af- traces passing in to outer ring, bundles passing in from outer ring- 

 to centre (diagrammatic). 



convergence lies probably far back in time, the habit and structure of 

 Monocotyledons being adaptations from the dicotyledonous form to their 

 peculiar conditions of life. That Peperomia is a reduced genus, compared 

 with Macropiper ; that the connection between Monocotyledons and Di- 

 cotyledons may perhaps be shown by an order siich as the Piperaceae, where 

 the one form, Peperomia, shows a reduction from the Macropiper form, the 

 reduction being in the direction of Monocotyledons. That the Piperaceae 

 are relatively an ancient family. They show a relation or resemblance to 

 Aroids, more particularly among Monocotyledons ; the key to the connec- 

 tion between Monocotyledons and Dicotyledons may perhaps be found 

 in a connection between the Piperaceae and Araceae. 



Hill, who "is in full accord with this view, that Peperoma is a reduced 

 genus," suggests " that the determining factor which has brought about 



