Minnesota Plant Life. 345 



axis so short that it is actually flat or even depressed in the 

 centre, as in roses. To this rule, however, there are a number 

 of important exceptions, as for example, the little mousetail, 

 a member of the crowfoot family, with its elongated axis, upon 

 which the nutlets are produced. The anemones, also, and 

 some of the rose family, like the strawberry, have conical or 

 cylindrical floral axes upon which the carpels are distributed. 

 These elongated axes may not, indeed, in such instances, be 

 really primitive, but may rather be secondarily adaptive. Yet 

 the highest types of flowers do not have such long axes, but are 

 flat, with the carpels central and the stamens in encircling rings. 

 If, now, one can imagine a pine cone, the tip of which is com- 

 posed of seed-bearing scales, while at the base are disposed the 

 pollen-scales or stamens, and then imagine further that the tip 

 of this axis is pressed down with the thumb until the whole 

 becomes flat and saucer-like, it is apparent that the seed-bearing 

 scales will now be at the centre, while the pollen-bearing scales 

 will form a ring around the outside of the saucer. Precisely 

 such change in shape of the ancestral cone is believed to have 

 taken place in the plant world under the slow workings of 

 structural improvements through the ages. Many advantages 

 in flowers might be derived by the passage from the elongated 

 to the flattened type of axis. If, for example, the flower came 

 to depend for pollination upon insects, the flattening of the axis 

 might make the work of the insects surer, or if the flower 

 depended upon its own pollen for pollination, the bringing of 

 the stamens and the stigmas into the same plane would, per- 

 haps, facilitate the process. Of course the ancient prototypes 

 of flowers could not be expected to have these flattened axes, 

 because in them the division of labor between spore-producing 

 and starch-making leaves had not arisen, and each leaf on the 

 axis had to stand in such a position that it could get light for 

 itself from the sun without shading too much the other leaves 

 near by. Elongated flower-axes, like those of the pines, remind 

 one of earlier days, in which such axes had, in addition to their 

 production of spores, also a starch-making work to perform. Any 

 flower which retains in its structure the marks of earlier, less 

 improved conditions, is conceived in this respect to be of lower 

 type than one which has lost these marks, and this is the true 



