Het onderscheid tussen Polygonum hydropiper L. en Polygonum mite Schrank

The surface of the ochrea of P. hydropiper seems to be smooth, but is in tact covered with hairs that are fused with the underlying tissue. The cilia at the upper edge of the ochrea are 0.2—2 (—3) mm long. The hairs on the ochrea of P. mite are fused with the tissue of the ochrea for half of their length at the most. The cilia are 3—7 mm long. The upper side of the leaf of P. hydropiper The upper side of the leaf of P. hydropiper is glabrous, the under side bears little hispid hairs on the midvein. The upper side of the leaf of P. mite is hairy on the midvein. the under side is hairy on midvein and lateral veins. Inflorescences of P. hydropiper have both 3- as well as 4-merous perianths, whereas those of P. mite have 4- and 5-merous perianths; the number of glands per perianth-segment is (20—) 30—50 in P. hydropiper and is o—ls in P. mite.