156 HARSHBERGER : PHYTO-GEOGRAPHIC SKETCH 
derived from an open prairie country, where, with frequent fires 
and the roaming of herds of buffaloes and antelopes, they have 
been subjected to environmental conditions very similar to those 
which are met with in the more highly cultivated districts of our 
eastern states. 
Plants derived from the native flora can hardly be looked upon 
as weeds (“plants out of place’’). Only a few of our troublesome 
weeds are native. The native plants have usually persisted in the 
soil when a road has been constructed, and in many places they 
are found in greatest abundance along the highways in rich arable 
land, because they have been left in undisturbed possession of the 
stretches of land on either side of the roadway, while the same 
species have been exterminated in the cultivated fields. In other 
cases native plants have migrated from the woods and natural 
meadows to the roadside and have implanted themselves there, 
especially in those districts of our country cut off from the railroad 
and other lines of cross-country travel. The plants in the follow- 
ing list are arranged according to their source: 
Europe. — Linaria Linaria (L.) Karst., Daucus Carota L., 
Phieum pratense L., Hypericum perforatum L., Rumex crispus L., 
R. obtusifolius L., R. Acetosella L., Verbascum Thapsus L., V. Blat- 
taria L., Plantago lanceolata L., Allium vineale L., Trifolium pra- 
tense L., T. arvense L., Chrysanthemum Leucanthemum L.., Arctium 
lappa L., Xanthium glabratum (DC.) Britton (X. strumarium L.), 
Anthemis Cotula DC., A. arvensis L., Taraxacum Taraxacum (L.) 
Karst., Cerastium vulgatuua L., Lactuca scariola L., Asparagus 
officinalis L., Saponaria officinalis L., Melilotus alba L.., Mollugo 
verticillata L., Carduus lanceolatus 1.., C. arvensis (L.) Robs. 
(Cnicus arvensis Hoffm.), Datura Stramonium L., D. Te atula L., 
Syntherisma sanguinalis (L.) Nash (Panicum sanguinale L.), Chae- 
tochloa glauca (L.) Scribn. (Setaria glauca Beauv.), Eleusine Indica 
(L.) Gaertn., Polygonum Persicaria L., Chenopodium album L., C. 
anthelminthicum L. (C. ambrosioides anthelminthicum Gray), Att 
plex hastata L., Amaranthus spinosus ., Portulacca oleracea L., 
Cerastium viscosum 1., Euphorbia Cyparissias L., Convolvulus 
arvensis L., Cichorium Intybus 1. 
Eastern North America. — Erigzron annuus (L.) Pers., Achillea 
Millefolium L., Plantago Rugelii Decaisne, Barbarea Barbarea (L.) 
