WEED ASSOCIATIONS BASED ON ENVIRONMENT. 11 



Crab-grass 89,600 Velvet Leaf 31,900 



Yellow Foxtail 113,600 Purslane Speedwell 186,300 



Pigweed 85,000 Dandelion 1,729 



Tumble-weed 14,000 Ragweed 23,100 



Purslane 69,000 Cocklebur 9,700 



Pepper-grass 12,225 Beggar-ticks 10,500 



Charlock 9,800 Ox-eye Daisy 6 S 750 



Shepherd's Purse 17,600 



WEED COMMUNITIES OR ASSOCIATIONS. 



Many weeds, like misery, love company. Certain species when 

 they travel go together and settle down in a little community on 

 a tract of land having an environment especially suited to their 

 taste and manner of growth. Thus along roadsides and cow-paths 

 one finds the knot-grass, black medic, wire-grass, dog-fennel, rib- 

 wort and prickly sida ; in barnyards the jimson-weed, mother- 

 wort, burdock, catnip, water-pepper and yellow dock; in lawns and 

 country yards the dandelion, common plantain, shepherd's purse 

 and round-leaved mallow. The most of these are so-called "social 

 weeds," forming company not only for themselves but for man 

 and accompanying him everywhere in his march across the conti- 

 nent. On the half-barren slopes of old fields there usually occurs 

 a little community made up of the evening primrose, mullen, field 

 sorrel, pennyroyal, cinquefoil, steelweed and ox-eye daisy, with 

 usually a few blackberry briers and a clump of fragrant everlast- 

 ing to bear them company. In rich soil along the borders of up- 

 land thickets occurs the figwort, ground ivy, blue lettuce, wood 

 nettles and trefoils; in open woodland pastures, the common 

 thistle, iron-weed, actinomeris, pokeweed, hawkweeds and Indian 

 tobacco; on river banks, especially near towns, the white sweet- 

 clover, bouncing bet, teasel, wormseed, milkweed, and prickly let- 

 tuce; while in rich alluvial lowlands grow the great horse-weed, 

 willow aster, cocklebur, bindweed, smartweed and wild sweet po- 

 tato. Numerous other plant associations could be mentioned but 

 the above are more than sufficient to show that weeds are gregarious 

 and that those which have similar tastes tend, like birds of a 

 feather, to flock together. 



THE ORIGIN OF INDIANA WEEDS. 



Having noted the various ways in which weeds are distributed 

 over the earth it is not surprising to find that in Indiana the great 

 majority of our very worst weeds are aliens from a foreign shore. 

 They are the ones which have succeeded best in crowding out and 



