Dispersal of Herbaceous A ngiosperms. 563 
irregular and papilionaceous. It is significant that of the 121 genera of 
the first two sub-families, 113 are entirely woody, and that the other 8 
contain both woody and herbaceous forms. There are no entirely herba- 
ceous genera. Counting the mixed genera as half woody and half 
herbaceous, this gives a percentage of only 3-3 of the genera which are 
herbaceous. Out of 304 genera of the Papilionatae, on the other hand, 187 
are entirely woody, 55 have both woody and herbaceous forms, and 62 are 
entirely herbaceous, making 29 per cent, of the genera herbaceous. It is 
evident that the more primitive members of the Leguminosae are almost all 
woody, but that there is a much higher percentage of herbaceous forms in 
the more recent portion of the family. 
The Violaceae are another example of the same thing. The Paypay- 
roleae and Rinoreae are almost certainly the most primitive members of 
the family from the simplicity and regularity of their flowers. The 8 genera 
which are included under them are all trees or shrubs. The Violeae, which 
from the irregularity of the corolla seem clearly to be more recent than the 
others, include the only two genera, Hybanthus and Viola, which contain 
herbaceous species. 
Of the two great families Araliaceae and Umbelliferae which form the 
order Umbelliflorae, the former undoubtedly have the more primitive, 
because the more varied, floral structure, and are probably much more ancient. 
With very few exceptions they are trees or shrubs. The Umbelliferae, on 
the other hand, which during the course of evolution have become sharply 
stereotyped as to floral plan, are almost entirely herbs. 
The same fact is noticeable among genera as well. Potentilla is 
divided by Wolf ( 15 ) into two sections, the Trichocarpae and the Gymno- 
carpae, and he considers the former from its floral structure to be clearly 
more primitive. Of its two subsections, the evidently more ancient 
Rhopalostyleae are all shrubby, and the more primitive members of the 
other subsection, the Nematostyleae, are shrubs or undershrubs. The 
Gymnocarpae are entirely herbaceous. 
Other instances of the same sort of thing might be brought forward. 
Among the Halorrhagaceae, for example, the two genera placed by Engler 
at the base of the family, Loudonia and Halorrhagis , are the only ones 
which ever approach a woody condition, the other genera being mainly 
aquatic plants. The sub-family Cobaeoideae, of the Polemoniaceae, which 
includes only trees and shrubs, is considered by Engler, on evidence from 
the reproductive organs, to be more primitive than the other sub-family, the 
Polemonioideae, which is entirely herbaceous. The Borraginaceae are 
divided into four sub-families, the Cordioideae, Ehretioideae, Heliotro- 
pioideae, and Borraginoideae ; and the first two of these, which are 
presumably the most ancient from their floral structures, consist entirely of 
trees and shrubs. The last two are, with very few exceptions, herbaceous. 
Q q 
