96 American Midland Naturalist Monograph No. 7 



14. Leaves ovate; peduncles pubescent; a- 



chenes about 3 mm long; stem 1-2 m 

 tall; waste places, roadsides, occasion- 

 ally spread from cult. Jime-Oct. Na- 

 tive of Eurasia. Prince's Feather. 



Kiss-me-over-the-garden-gate 



- P. orientale L. 



13. Stems and peduncles not glandular-hispidu- 

 loiis or pubescent. 



15. Panicles compact, ellipsoid, 7-10 mm 



thick; leaves often with a more or less 

 evident dark blotch; flowers pink; cult, 

 ground, waste places, roadsides, fields, 

 common; nat. from Eur. May-Sept. 



Lady's Thumb P. persicaria L. 



15. Panicles slender, lax or interrupted; 

 achenes trigonal. 

 16. Sheaths strigose; calyx white or green- 

 ish; plants perennial; wet ground 

 or in shallow water, common. July- 

 Sept. [P. opelousanum Riddell; P. 

 setae eum Baldw.]. Mild Water- 

 pepper P. hydropiperoides Michx. 



16. Sheaths glabrous; calyx rose; plants 

 annual; moist waste ground about 

 towns; native of trop. eastern Asia. 

 June-Oct. {P. caespitosum Blume] 



P. longisetum De Bruyn 



10. Stipular sheaths not ciliate (except rarely some of the 



uppermost) ; calyx not punctate; achenes glossy, 



lenticular; plants annual. 



17. Peduncles with short-stipitate glands; achenes 



about 3 mm wide; panicles erect; cult, ground, 



roadsides, fields, or along ditches, abundant 



probably in every county. Aug.-Oct. [P. longi- 



stylum Small] P. pensylvanicum L. 



17. Peduncles with sessile glands, or glabrous; achenes 

 1.8-2 mm wide; panicles drooping or erect; 

 moist soil, common; probably nat. from Eur. 

 July-Sept. [P. tomentosum Schrank; P. inear- 



naturn Ell.]. Pale Smartweed 



P. lapathijoHum L. 



7. Stem retrorsely bristly; leaves sagittate or hastate. 



18. Leaves sagittate; stems 4-angled; stamens 8; style 3- 

 parted; achenes trigonal; wet ground, not common. 



July-Oct. Arrow-vine P. sagittatum L. 



18. Leaves hastate; stem ridged; stamens 6; style 2-parted; 

 achenes lenticular; swampy ground, apparently not 

 recently collected in 111 P. arijoliurn L. 



