3^6 



Minnesota Plant Life. 



criterion of rank among flowers. Precisely the same thing is 

 apparent in human society, for a civiHzed man who retains char- 

 acteristics which may have been vahiable to the savage but have 

 been outgrown during the progress of civihzation. is regarded 

 as of lower grade than his fellows. 



The flattening of the axis of the flower into a disk is pos- 

 sibly the most fundamental evidence of improvement; that is, 

 of passage from a lower to a higher type. Connected with 

 this flattening arose a rearrangement of the parts of the flower. 

 In the pine cone the scales are arranged spirally, just as if they 

 were foliage leaves, but in apples the stamens and carpels are 

 produced in whorls. A spiral arrangement of stamens and 

 carpels, because it is more like the fundamental grouping of 

 foliage leaves upon a stem, is believed to indicate a lower type 

 of flower than when whorls are substituted — a grouping not 

 so common among foliage leaves, but quite unobjectionable for 

 spore-producing leaves. Even among the pines the tendency 

 to gather the leaves of the flower into more compact clusters 

 may be seen in such plants as the junipers and red cedars. 



Again, as flowers came to be blocked out as definite spore- 

 producing tracts, made up of leaves arranged on a shortened 

 axis, the leaves below the stamens became modified from their 

 proximity to the true floral parts. Thus the area known as 

 perianth came into existence. By a further specialization peri- 

 anth came to consist of outer perianth — that is, lower perianth, 

 or calyx, and inner — that is, upper perianth, or corolla. Under 

 such conditions what may be known as a typical flower ap- 

 peared, and such a typical flower may be described as an axis, 

 bearing essential leaves, viz., carpels and stamens, surrounded 

 by the accessor)^ leaves of the calyx and corolla. 



In all the four regions of the typical flower modifications 

 and improvements are possible. The carpels, for example, may 

 blend together into a single fruit-rudiment or pistil. Thus the 

 fruit of the lily is regarded as made up of three carpels blended 

 together. Such a blending would be regarded as an improve- 

 ment over the separate condition of the scales in the cones of 

 the pine. It is certainly farther removed from that primitive 

 arrangement in which, on account of their starch-making duties, 

 the leaves were necessarily separate. After having thus be- 



