Fig 32. [Wild Buckwheat. Polygonum Convolvulus] L.

Wild Buckwheat. Polygonum Convolvulus L. Achenes dull, jet-black, equally 3-sided, elliptical to obovoid, minutely granular often with faint longitudinal striation, the faces often more or less concave, the angles rounded, 2.5–3.5 mm. long, sometimes with the remains of calyx attached. Introduced from Europe. Often climbing up corn stalks.

Fig 33. [Erect Knotweed. Polygonum erectum] L.

Erect Knotweed. Polygonum erectum L. Achenes dull, light to dark brown, unequally 3-sided, ovoid or rhombic, finely granular and striate lengthwise, the faces sometimes concave, the angles rounded, 2.5–3 mm. long, sometimes with the remains of calyx attached. Native to this country. Of little account.

Fig 34. [Smart-weed. Polygonum Hydropiper] L.