788 WEED FLORA OF IOWA 



BLOOMING PERIOD OF COMMON WEEDS— Continued. 



Acalypha virginica A. Three-seeded mercury 



Amaranthus graecizans A. Tumbleweed 



Amaranthus blitoides A. Spreading pigweed 



Anthemis cotuila A. Mayweed 



Apocynum cannabinum P. Dogbane 



Asciepias syriaca P. Milkweed 



Berteroa incana A. or P. Berteroa 



Brassica nigra A. Black mustard 



Bromus seaalinus A. Cheat 



Camelina sativa A. False flax 



Carex vulpinoidea P. Sedge 



Cheno.podium album A. Lamb's quarter 



Cieuta maculata P. Cowbane 



Cirsium arvense P. Canada thistle 



Cirsium undulatum B. Wavy-leaved thistle 



Crotalaria sagittalis A. Rattle-box 



Cycloloma atriplicifolium A. Winged pigweed 



Datura stramonium A. Jimson weed 



Daucus carota B. Wild carrot 



Erigeron annuus A. Fleabane 



Erigeron canadensis A. Horseweed 



Erigeron ramosus A. Branched fleabane 



Euphorbia maculata Spotted-leaved spurge 



Geum canadense P. Avens 



Helianthus petiolaris A. Petiolate sunflower 



Hordeum jubatum A. or B. Squirrel-tail 



Hypericum perforatum P. St. John's-wort 



Lactuca canadensis A. or B. Wild lettuce 



Lactuca pulchella P. Blue lettuce 



Lappula virginiana A. Beggar's lice 



Leonurus cardiaca P. Mother-wort 



Lygodesmia juncea P. Lygodesmia 



Melanthium virginicum P. Bunch flower 



Melilotus alba B. White sweet clover 



Oenothera biennis B. Evening primrose 



Parietaria pennsylvanica A. Pellitory 



Pastinaca sativa P. Parsnip 



Plantago rugelii P. Rugel's plantain 



Polanisia trachysperma A. Polanisia 



Polygonum aviculare A. Dooryard knotgrass 



Polygonum hydropiperoides P. Mild water pepper. 

 Polygonum lapathifolium A. Slender smartweed... 



Elensine indica A. Goose-grass 



Eragrostis megastachya A. Candy-grass 



Linaria vxilgaris P. Toadflax 



Silene antirrhina A. Sleepy catchfly 



Thlaspi arvense A. Pennycress 



Urtica gracilis P. Nettle 



Conringia orientalis A. Hare's-ear mustard 



Polygonum persicaria A. Lady's thumb 



Portulaca oleracea A. Purslane 



Radicula armoracia P. Horseradish 



Raphanus sativus A. or B. Radish 



Rumex crispus P. Curled dock 



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