420 REPORT OF NEW JERSEY STATE MUSEUM. 



//. Calyx loljcs entirely covering the achene. 



P. hydropipcroides, p. 422 

 hh. Calyx lobes shorter than the achene. 



P. It. opeloiisanum, p. 422 



ggg. Leaves 150x20 mm., bristles 12 mm. long, flowers 



usually whitish. P. setaceum, p. 424 



ff. Racemes drooping. P. careyi, p. 422 



ee. Racemes slender, interrupted. 



f. Achene dull. [P. hydro piper]'* 



ff. Achene smooth and shining. 



g. Leaves hispid above 150x20 mm. 



P. setaceum, p. 424 

 gg. Leaves glabrous. 



h. Leaves 100x15, plant medium. 



P. pnnctattun, p. 423 

 hh. Leaves 140 x 35, plant tall. 



P. p. robustius, p. 423 

 bb- Flowers in a very long terminal, naked, interrupted raceme, calyx 

 four parted, leaves ovate, acuminate. P. virginianum, p. 424 



bbb. Flowers axillary or in small axillary clusters, plants prostrate or 

 erect. 

 c. Plants prostrate. 

 d. Foliage nearly white, maritime. P. maritimum, p. 424 



dd. Foliage bluish green. P. aviculare, p. 424 



cc. Plants erect. 



d. Stems sharply angled, leaves linear. P. tenue, p. 425 



dd. Stems terete. 



e. Leaves elliptic obtuse. P. erectum, p. 424 



ee. Leaves lanceolate acute. 



f. Pedicels exscrted, leaves lanceolate, acute. 



P. atlanticum , p. 425 

 //. Pedicels covered by the sheaths, leaves linear, oblong, 

 often obtuse. P. proliUcum, p. 425 



bbbb. Flowers in axillary and terminal clusters or panicled racemes, climb- 

 ing vines. 

 c. Outer segments of fruiting calyx keeled, not winged. 



{P. convolvulus]* 



cc. Outer segments of fruiting calyx winged. P. scandens, p. 426 



bbbbb. Flowers in capitate clusters or racemes, stems covered with recurved 



prickles. 



c. Leaves sagittate. P. sagittatum, p. 426 



cc. Leaves halberd-shaped. P. arifolium, p. 426 



* All the Polygonums seem to have a tendency to become weeds. P. 

 aviculare, P. erectum, P. pennsylvanicum and P. careyi, while natives of 

 North America, seem to be entirely weeds, to-day, within our limits, and to 

 these may be added P. hydropiper, Common Smartweed, P. persicaria, Lady's 

 Thumb, and P. convolvulus, Black Bindweed, all common in waste or culti- 

 vated ground, and all natives of Europe, though the first does occur native 

 in the northwest. The brilliant crimson-spiked Prince's Feather, P. orientale, 

 of old garden , sometimes escapes into waste groun-J. 



