20 BOTANICAL GAZETTE [JANUARY 
to but a few points, points which involve, however, no end of 
difficulty. The two theories would apparently be reduced to one 
if we could say which of the following are primitive: monospo- 
rangiate or amphisporangiate flowers; presence or absence of a 
perianth; anemophily or entomophily. Of possibly less impor- 
tance is the question whether the angiospermous flower is a modified 
simple (that is, unbranched) shoot or a modified infloresence. There 
is agreement as to the primitiveness of such characters as actino- 
morphy, freedom of floral parts, dicotyledony, lack of true vessels 
in the vascular strands, and prevalence of woody plants. So it 
seems important to discuss the differences cited. 
The fact that certain characters are common to all or nearly all 
gymnosperms seems in many instances to be one of the strongest 
reasons for regarding those characters as primitive if they occur 
at all among angiosperms. Among these supposedly primitive 
characters are dicotyledony, prevalence of woody plants, and 
absence of tracheae in the conducting strands. For the same reason 
we might conclude that primitive angiosperms were anemophilous 
and possessed naked, monosporangiate flowers, since these char- 
acters also are common to most gymnosperms. 
Before discussing this matter further, reference may be made 
to the possibility of there being two entirely separate lines of dicoty- 
ledons. Reasons have been given for believing that angiosperms 
are monophyletic. Now if the similarity between dicotyledons 
and monocotyledons is close enough to warrant such a conclusion, 
then, since the similarity is so much more striking among dicoty- 
ledons themselves, this conclusion seems all the more certain in 
the latter case. In the group Dicotyledoneae the diversity in the 
development and structure of the gametophytes and embryos is 
surely less marked than is the diversity among angiosperms as 4 
whole, and so difficulties are increased accordingly if any other 
than a monophyletic theory ‘is proposed for the phylogeny of 
dicotyledons. It is certainly true that the reproductive structures 
and organs of spermatophytes are among their least plastic features. 
While it is dangerous to emphasize too strongly the importance of 
even the most stable character to the exclusion of others, never- 
theless, if the view that the embryo sac points unmistakably to a 
