THE SELECTION OF PLANT TYPES. 2OI 



form. Of the Gymnosperms only the largest and most impor- 

 tant group, the Conifers, is represented in our temperate flora. 



1 1 . Larix decidna, the European larch, is very commonly 

 planted as an ornamental tree, and possesses advantages over 

 most other available species. Its fertile cones mature in the 

 same season in which they appear, and their tissues do not 

 become inconveniently hard for cutting until quite late. Both 

 sorts of cones are produced pretty freely on the lower branches, 

 where they are readily accessible. In structure the cones are 

 as typical as those of the pine or spruce, and in one or more of 

 the respects above mentioned they are better than those. 



12. Fagopynnn, the cultivated buckwheat, or a large-flowered 

 species of Polygonum may perhaps serve as well as anything if 

 it is desired to follow out the angiospermous life history in a 

 single plant. On the other hand, many of the Liliaceae show 

 the arrangement of cells in the embryo sac before and up to the 

 time of fertilization with especial clearness, and many other 

 plants are particularly favorable for the study of certain other 

 details. The bean and other Legnminosae show the structure 

 of a primitive ovary, but its ovule is peculiar, and the absence 

 of a permanent endosperm in the seed is a disadvantage. 



It must be evident that this is not an attempt to furnish a 

 guide to the study of the types proposed. A few of the more 

 salient features illustrated by the forms suggested have been 

 barely mentioned, and may serve as hints, to be taken for what 

 they are worth. But enough has perhaps been said to make 

 clear the writer's conviction that phylogenetic considerations are 

 important in such a course. The general idea of progressive 

 development and increasing complexity ought to be everywhere 

 brought out to give coherence and unity to the work. But 

 this is impossible if the course be a helter-skelter mixture of 

 plant and animal types. It may be urged that the sequence of 

 types in the latter case is never an unconsidered one, but allows 

 an instructive comparison of certain plants with certain animals. 

 Granting this, it is yet difficult to see how any adequate com- 

 pensation for the sacrifice of conceptions of descent and 

 relationship is possible. Biology without phylogeny may be 

 compared to a cell deprived of its nucleus, not dead, perhaps. 



