726 REPORT OF STATE GEOLOGIST. 



P. aviculare L. Knot-grass. Doorweed. 



A troublesome weed in lawns and along paths. Growing also 

 abundantly along roadsides and in waste places, usually in dry, 

 rather compact soil. Common in all parts of the State. 



Flowers from June until November. 



Tippecanoe (Cunningham); Jay, Delaware, Randolph, and 

 Wayne (Phinney); Noble (Van Gorder); Gibson and Posey 

 (Schneck); Jefferson (Barnes); Putnam (MacDougal); Franklin 

 (Aieyncke); Clark (Baird and Taylor); Knox (Spillman); Fayette 

 (Hessler); Vigo (Blatchley); Kosciusko (Coulter); Hamilton and 

 Marion (Wilson); Steuben (Bradner). 



P. erect um L. Erect Knot-grass. 



Widely distributed throughout the State, but not so abundant 

 as the preceding. It grows about yards and along roadways, but is 

 more abundant in moist, rather rich soils. 



Flowers from July through September. 



Tippecanoe (Cunningham); Noble (Van Gorder); Jay, Dela- 

 ware, Randolph and Wayne (Phinney); Clark (Baird and Taylor); 

 Vermillion (Wright); Gibson and Posey (Schneck); Jefferson 

 (Barnes); Putnam (MacDougal); Franklin (Meyncke); Fayette 

 (Hessler); Vigo (Blatchley); Hamilton and Marion (Wilson); 

 Steuben (Bradner). 



P. ramosissimum Michx. Bushy Knotweed. 



In low, sandy soils in a few counties of the State. The north- 

 ern station along the shore of Lake Michigan is a fairly natural 

 one. It is barely possible that the plants from the southern sta- 

 tion should be referred to the western form, P. ramosissimum 

 prolificum Small. 



Flowering in July and August. 



Vigo (Blatchley); Lake (Hill); Porter (Cowles). 



P. tenue Michx. Slender Knotweed. 



In rich, loose, dry soil in a few counties of the State, but no- 

 where abundant. Chiefly northern in its range in our territory. 

 Flowers from July through September. 



Tippecanoe (Coulter); Lake (Hill); Vigo (Blatchley); Porter 

 (Cowles). 



