160 FLORA OF WINNESHIEK COUNTY. 
and glabrum). Blue grass (Poa pratensis) is often a persistent 
weed. The less pernicious, or less abundant, introduced weeds 
are: the panic grasses (Panicum sanguinale, capillare and 
dichotomum), the fox-tail grasses (Setaria glauca and viridis), 
Eragrostis major, both kinds of chess (Bromus secalinus and 
racemosus commutatus), orchard grass (Dactylis), St. John’s- 
wort (Hypericum perforatum), lamb’s quarters (Chenopodium 
album), hedge mustard (Sisymbriwm officinale), false flax 
(Camelina), low hop clover (Trifolium procumbens), sheep- 
sorrel (Rumex acetosella), patience dock (R. patientia), Rus-~ 
sian thistle (Salsola), mullein (Verbascum), speedwell (Veron-. 
ica peregrina), hemp (Cannabis), black nightshade (Solanum 
nigrum), ground cherry (Physalis pubescens), motherwort. 
(Leonurus), chicory (Cichorium), tansy (Tanacetum) and: sow- 
thistle (Sonchus). : 
The following native weeds are more or less seorMideornas 
squirrel-tail grass (Hordeum), wire grass (Juncus tenuis), 
water dock (Rumesx brittanica), smart-weed (Polygonum penn- 
sylvanicum), pepper-grass (Lepidium virginicum), partridge- 
pea (Cassia chamaecrista), white clover (Trifolium repens), 
three-seeded mercury (Acalypha), the native spurges (Huphor- 
bia), velvet-leaf (Abutilon), yellow oxalis (Oxalis stricta), even- 
ing primrose (Onagra biennis), milkweed (Asclepias syriaca), 
the dodders (Cuscuta), nyctelea (Macrocalyx), beggar’s lice 
(Lappula), the verbenas (Verbena) both species of Scrophu- 
laria, Rugel’s plantain (Plantago rugeli), slender nettle (Urtica 
gracilis), bur-weed marsh-elder. (Iva), both ragweeds (Artem- 
isia trifida and artemisaefolia), cocklebur (Xanthium), horse-. 
weed (Leptilon), daisy flea-bane (Erigeron strigosus), tall eone- 
flower (Rudbeckia laciniata), several species of sunflowers. 
(Helianthus annuus, grosse-serratus, rigidus, etc.), Spanish 
needles (Bidens) and fire weed (Erechtites). Muhlenbergia 
mexicana sometimes becomes a weed, and the sand-bur (Cen- 
chrus) is often troublesome in sandy fields. For additional 
notes on all these species see the annotated list. 
Individual effort avails but little in the conflict with weeds. 
Until concerted systematic and intelligent action is taken 
against them men will continue to suffer great loss from this: 
source. Fire, the plow, and the scythe or mower are the most 
