162 
ation of the species, but attractive colors and odors are not needed. 
Writers on the subject distinguish the former as entomophilous, the 
latter as anemophilous plants. 
To apply these observations, let the Exogens in Vasey’s list of trees 
and in Gray’s Manual be divided into two sections, the second section 
in each beginning with Oleaceze. In general the orders in the first 
section are marked by flowers attractive to insects ; in the second, by 
anemophilous flowers. Vasey has 413 exogenous trees—z202 of these 
precede Oleacex, or nearly one-half. But this first section, the 
section of entomophilous plants, comprises only 60 of the 264 dicli- 
nous exogens, the remaining 204 being anemophilous. Of the species 
in Gray’s Manual there are 1593 before Oleacez with 51 diclinous 
trees; the remaining exogens are only 258 with 110 diclinous trees 
—an enormous disproportion. These r1o diclinous trees are mostly 
comprised in 8 orders, viz., Oleacez, Lauracez, Urticacee, Juglan- 
dacez, Cupuliferz, Betulaceze, Salicacesee, Conifer. In these orders 
‘are found most of our forest trees, with large stigmas, abundant 
pollen, numerous individuals, social in habit, and rearing their heads 
to the sky to catch the breezes so necessary for their fertilization. 
Whether anemophilous trees have acquired their height and their 
firm fibre in consequence of their diclinous ‘flowers, or their floral 
character from their other habits, is a question. Mr. Darwin inclines 
to the first view, It is not, however, necessary for wind fertilized 
plants to be tall or woody; all that is needed is that the wind should 
have a free passage from one to the other, an end which would be 
equally secured by having the plants social, about the same height 
and free from interposing strangers, as we may see in the waste 
places covered with Amdrosta trifida, or other species of this anemo- 
philous genus. But a more interesting example is furnished by the 
prairies covered with grass and the marshy flats with sedges. Refer- 
ence has before been made to the large proportion of diclinous plants 
among Endogens, and the small proportion of woody species. The 
two large orders we are speaking of are mostly wind fertilized, and 
moreover well adapted to grow where woody plants will not, as Prof. 
J. D. Whitney has shown in his articles on the prairies in Vol. X. of 
the American Naturalist. They had no need, therefore, to become 
woody, and no power, in such soils. Their social habits, moreover, 
secure them to a great degree from other herbaceous rivals. 
Mr. Darwin is of opinion that plants were originally diclinous, and 
that the insect-fertilized trees and shrubs have become monoclinous 
after the appearance of insects. Perhaps they were outstripped in 
growth by the others and could only survive by means of other adap- 
tations. In general they are more lowly than the diclinous, though 
there are some remarkable exceptions—Eucalyptus and some 
Leguminose for example. The Salices present an intermediate stage, 
for the Willows, which are for the most part low, are visited by 
insects, while their taller relatives, the Poplars, are wind fertilized. 
The woody climbers and the mistletoes seem to have preserved their 
original separate flowers by having at an early epoch availed them- 
selves of the height of their neighbors. ‘ oo 
Anemophilous plants are generally biennial or perennial, and also 
