Polygonum cespitosum Blume

Polygonum cespitosum plant

Family - Polygonaceae

Stems - Thin, herbaceous, from fibrous roots, erect to reclining, to +40cm tall, reddish with age.

Leaves - Alternate, short-petiolate, lanceolate to rhombic, to 8cm long, 2cm wide, mostly glabrous or sparsely pubescent. Ocrea fringed with long cilia. Cilia equaling or longer than ocrea.

Polygonum cespitosum ocreaOcrea.

Polygonum cespitosum leaves

Inflorescence - Axillary and terminal racemes, sometimes branching into a loose panicle. The clusters 2-3cm long (tall), -1cm wide (thick), dense. Bracts subtending flowers with ciliate margins, the cilia equaling or typically longer than the flowers.

Flowers - Perianth parts 5, reddish to pinkish-rose or with some white, 2-3mm long, smooth to rugose. Stamens and styles included within perianth. Achenes 3-sided, to 2.5mm long, black.

Polygonum cespitosum flowersFlowers with cilia.

Flowering - May - September.

Habitat - Moist ground, disturbed sites, waste ground, ditches, roadsides, railroads.

Origin - Native to U.S. and Asia.

Other info. - Most of the smaller plants of this genus look very similar. Species can usually be identified by the cilia (or lack of) on the ocrea and the bracts subtending the flowers. Stem pubescence and leaf shape are other determining factors. This species is a bit easier to tell because of its red clusters of small flowers, which have the long cilia.
Many plants of this genus are mildly toxic and cause a smarting sensation (= burning) when chewed.

Photographs taken along the shores of the Current River, Shannon County, MO., 9-20-03.


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