Floral Evolution. 
75 
having any real significance. In the first place, the vegetative 
system of Najas suggests that it, like so many other flowering 
aquatic plants, is probably the reduced descendant of terrestrial 
forms. Again, although the female flower is naked, the male has a 
perianth ; this surrounds a single anther, and the male flower is 
therefore, like the female, represented by a single sporangium. 
The case is very different with the male sporocarp in Azolla, where 
an indefinite number of microsporangia are borne upon a central 
columella. Which of these two are we to regard as the more 
primitive character, the solitariness of the female sporangium, or 
the aggregation of the male sporangia in indefinite numbers ? We 
shall return to this point later. 
Mention should be made, too, of the presence of three styles 
in the female flower of Najas, suggesting the derivation of the 
ovary from three carpellary leaves. If this be the case, we are face 
to face with characters the reverse of primitive, namely, the fusion 
of sporophylls, and the association of but one sporangium with 
three sporophylls. We search in vain outside the Angiosperms for 
indications of such characters; although at the same time, the 
details of development in the ovary of Najas 1 leave the question 
somewhat open as to whether the structure enclosing the ovule is 
the true homologue of sporophyll tissue, as it is unquestionably 
in the case of many wide groups of Angiosperms to be referred 
to shortly. Lastly, the anatropy of the ovule in Najas has no 
little weight in throwing doubt upon the primitiveness of this 
form. 
One or two members of the Piperaceae have been selected, 
with more reasonable justification perhaps, as representing primitive 
types illustrative of this first group of views. In Peperomia, for 
instance, the spadiciform inflorescence is composed of definite 
hermaphrodite entities, properly termed “ flowers ” although they 
are naked, each being subtended by a bract. The ovary encloses a 
single basilar orthotropous ovule, and each pistil is associated with 
two or more stamens. 
The female portion of this flower is thus free from the more 
obvious objections to primitiveness, which we have noted in Najas ; 
and although the Piperaceae display a considerable amount of 
plasticity morphologically, the habit of these plants is not so 
specialized as that of the flowering aquatic. Other details of 
1 Rendle. “ A Systematic Revision of the Genus Najas.” Trans, 
Linn, Soc, Ser, ii, v. 379, 1899, 
