10 
EDMUND W. SINNOTT AND IRVING W. BAILEY 
smaller ones are simple palmate or pinnate. This fact is illustrated 
for Acer, Viburnum and Ampelopsis in figures 3, 5 and 6, 18 and 19, 
and 20 and 21. It has been observed by the writers in practically 
all families possessing palmately lobed leaves. There are also cases 
where a vigorous twig or stool shoot will produce this type of foliage 
although the typical leaf for the species is simple (figs. 72 and 73). 
Evidence from morphology is therefore decidedly against the 
claims to primitiveness of the pinnate simple and pinnate lobed types, 
and as between the other four is clearly in favor of the greater antiquity 
of one of the palmate forms. Let us see whether such phylogenetic 
evidence as is available will permit a further narrowing down of the 
field. 
Phylogenetic Evidence 
Phylogenetic evidence first supports that from other sources in 
pointing to the simple pinnate leaf as more recent than the others, 
for it is overwhelmingly predominant in the Metachlamydeae. Of 
the 1,245 woody genera of this subclass enumerated by Engler 1,110 
are simple pinnate, or 89 per cent; and of the 4,840 metachlamydeous 
species in the floras analyzed above, 3,780, or 78 per cent, are simple 
pinnate, and 400, or 8 per cent, are pinnate lobed, a total of 86 per 
cent. Of the 2,150 woody Metachlamydeae in these floras 1,915, 
or 89 per cent, have simple pinnate leaves. A type of leaf so closely 
associated with specialized floral structures is not likely to be very 
primitive. On the other hand, 70 per cent of the palmate simple 
type, 90 per cent of the palmate lobed, 93 per cent of the palmate 
compound and 88 per cent of the pinnate compound are included in 
the Archichlamydeae. 
Of the four remaining types the pinnately compound, although 
developed for the most part among the Archichlamydeae, is found 
principally in the Juglandaceae, Rosaceae, Leguminosae, Zygophyl- 
aceae, Sapindaceae, Rutaceae, Simarubaceae, Burseraceae, Meliaceae, 
Anacardiaceae, Araliaceae, Umbelliferae, Bignoniaceae and Oleaceae, 
none of which are generally regarded as being particularly ancient 
families. On phylogenetic evidence, therefore, the pinnately com- 
pound leaf cannot well be considered a primitive one. 
To settle our problem we should be better acquainted than at 
present with the phylogeny of the Angiosperms. As to just what 
modern families should be regarded as closest to the ancient stock 
