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Pale Smartweed

Persicaria lapathifolia


This annual plant is about 2½–4' tall, branching occasionally. The stems are light green, terete, hairless, and somewhat swollen at the petiole bases. The alternate leaves are up to 8" long and 2" across; they are medium to dark green, lanceolate, glabrous or slightly pubescent, and their margins are smooth. At the petiole bases, there are membranous sheaths (ocreae) that wrap around the stems. These sheaths often have longitudinal ribs, but they lack bristles along their upper margins. With age, the sheaths gradually turn brown and peel away. The upper stems terminate in spike-like racemes of flowers. These racemes are about 2-8" long, and they droop conspicuously downward. The small flowers are densely crowded together along the length of each raceme. Each flower is about 1/8" (3 mm.) long, consisting of 5 tepals and the reproductive organs. These tepals are usually white or greenish white; less often they are light pink. Because the flowers don't open fully, the inner tepals can be difficult to observe. The flowers have inconspicuous pedicels (less than 1 mm. in length). The blooming period occurs from mid-summer to early fall, and lasts about 1½-2 months. There is no noticeable floral scent. The seeds are dark brown or black, ovoid and bluntly 3-angled in shape, and up to 2 mm. across. The flattened sides of the seeds are slightly concave and their surfaces are shiny. The root system is shallow and fibrous. This plant spreads by reseeding itself, often forming colonies at favorable sites.

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Spotted by

Wisconsin, USA

Spotted on Sep 4, 2015
Submitted on Oct 17, 2016

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