166 A. Gray—Pertinacity and Predominance of Weeds. 
oe ge 
2s 
8 
Cirsium lanceolatum. 
Lappa officinalis. 
Cichorium In 
bus 
Leontodon autumnale, 
m Dens-leonis. 
erbascum Blattaria. 
inaria vulgaris. 
Mentha viridis. 
Mentha soit 
Polygonum aviculare. 
Polygonum Convolvulus. 
Penis crispus 
Rum sanguin ine 
Rumer asetonelta! 
m vineale. 
ies: pret: 
Phleum praten 
pede madgars 
Agros 
Dactyis flomersia 
Poa 
Poa hereme 
Calamintha Nepe a pratensis 
Genista tinctoria. falamintha Clinpodiam. Poa trivialis 
Trifolium arvens repeta Cata Eragrostis poseoides. 
Trifolium agrarium epeta Pe ce Festuca ovina. 
Trifolium repens ium re Festuca pratensis. 
Daucus Carota aleopsis Tetrahit. 3romus secalin 
Pastinaca sa ] urus Cardi olium perenne. 
Conium maculatum ium amplexicaule mr 
Tussilago Farfara. ichium vulgare. tt anin 
ula Helenium. mphytum officinale. Anthoxanthum odoratum. 
nag Bre Memes Echinospermum Lappu Panicum glabrum. 
Anthemi: ynoglossum officinale Panicum sanguinale 
eg ee Vile Solanum nigru tcum Crus-gall: 
F podium a Setaria glauca. 
Chenopodium hybridum. Setaria viridis. 
Tevesntienam n vulgare, 
Cirs Chenopodium Botrys. 
The plants of es list, I a as weeds, are of very various 
character; and sev such as White Clover and most 
of the e grasses, wher is most doniiniars do not fall under the ordi- 
as definition of weeds at all, but under that of" plants useful to 
the farmer. Some, like Purslane, are only garden-weeds; some 
belong to pastures ‘isa meadows; others affect road-sides. The 
fewness of European corn-weeds is remarkable. Chess and 
Corn-cockle (Lychnis Githago) are the only ones on the list. 
Corn Poppy, Blue-bottle and Knapweed (Centaurea Oyanus and 
C. nigra) and Larkspur are conspicuously wanting; but the 
last are not wholly unknown in some parts of the country. 
But the only aig before us is, whether these plants intro- 
duced com Europe or are not self-fertilized, or more 
habitually so than oitbietes so that this may be accounted an 
. of prey redominance. Apparently this “question 
t be answered in the negative. The question is not 
ghether they are self fertilizable. The great pr ohes A of plants 
are so, even of those specially adapted for intererossing. The 
its of this list appear to belong to the juste ilies Only 
one (Rumex Acetoseila) is completely dicecious ; a few are incom- 
at dicecious or polygamous ; ; the two species of Plantago are 
us to the extent of nt dioicism or monoicism ; 
a 0 lege number of the corolline species are either proterandrous 
‘oterogynous, including two or three anemophilous species, 
