696 WEED FLORA OP IOWA 



alien immigrants he gives as follows: Mediterranean region, 33 

 species ; tropical America and warm temperate regions, 13 ; tropical 

 Africa, 16; Australia, 1; temperate Nortli America, 1; temperate 

 South. America, 1; uncertain origin, 16. It is interesting to note 

 that the following Iowa species are abundant and troublesome in 

 the Transvaal (the exceptions being capitalized) : mayweed 

 (Anthends cotula), black mustard (Beassica nigra), hemp {Can- 

 nabis sativa), shepherd's purse (Capseli/A buesa-pastobis) , goose- 

 foot (Ghenopodium album), wormseed {Chenopodiwm ambro- 

 sioides), nut grass (Cyperus escvlentus), jimson weed (Datura 

 stramonium), wire grass {Eleusine indica), fleabane (Erigeron 

 canadensis), shoo-fly {Hibiscus trionum), common morning-glory 

 (Ipomoea pubpueea) , load flax (Linabia vtiuiAEis) , darnel {Lalium 

 temulentum), lady's sorrel {Oxalis oorniculata) , ribgrass {Plantago 

 la/nceolata) , common plantain {Plantago major), black bindweed 

 (PoLTGONTjM CONVOLVULUS) , larger fcttotwced {Polygormm erectum), 

 purslane {Portulaca oleracea), jointed charlock {Baphanus rapha- 

 nistrum), sheep sorrel {Bumex a^etoselhi) , yellow dock (Rumex 

 CEisPus), smooth tobacco {Nicotiama glauca), cow-herb (Saponaeia 

 vaccabia), bristly foxtail {Seta/ria verticillata) , black nightshade 

 {Solamim, nigrum), dandelion {Taraxacum officinale), chickweed 

 {Stellaria media), sow thistle (Sonchus ouebageos) , goat's beard 

 (Teagopogon poeeipolius) , vetch (Vicia sativa). In addition to 

 the above plants, Davy lists quite a number which are common in 

 the states to the south of Iowa and in California. Such plants as 

 castor-oil bean {Biciwws communis), zinnia {Zinnia pauciflorus), 

 marigold {Tagetes erecta), cosmos {Cosmos bipinnatus), cockscomb 

 {Celosia cristata), four-o'clock {Miraibilis jalapa), evening primrose 

 {Oenothera gramdiflora) , Xylopleurum tetrapterum, Mexican poppy 

 {Argemon'e mexicana) are commonly cultivated in Iowa. Some, like 

 Argem,one, Oenothera and Cosmos, occasionally escape in Iowa. In 

 a classification of these weeds, Davy places the alien plants under 

 the following heads : I. Colonists (species not yet showing signs 

 of spreading) ; shepherd's purse {Capsella bursa-pastoris) , eat's-ear 

 {Hypochaeris radicata), (one of the most common weeds on the 

 Pacific coast and spreading in New England, not reported from 

 Iowa), black bindweed {Polygonum convolvulus) (common every- 

 where in Iowa), toad-flax {Lvnaria vulgaris) (common in the 

 north). II. Adventive (occasional, but spreading); mayweed 

 {Anth&ms cotula), Mexican poppy {Argemone mexicana). Cosmos 

 bipinnatus, morning-glory {Ipomoea purpurea), darnel {Lolium 



