Polygonum hydropiperoides Michx.

Polygonum hydropiperoides plant

Family - Polygonaceae

Stems - To +70cm tall, from fibrous roots, multiple from base, erect, herbaceous, glabrous or with sparse appressed antrorse hairs, branching.

Leaves - Alternate, sheathing, linear-lanceolate, entire, attenuate, scabrous with sparse short appressed pubescence, to -15cm long, +/-1.5cm broad. Ocrea to +/-1.5cm long, fringed with ciliate ferruginous bristles to -1cm long, with antrorse appressed pubescence.

Polygonum hydropiperoides leaves

Polygonum hydropiperoides ocreaOcrea.

Inflorescence - Loose terminal spikiform racemes to +/-10cm long. Ocreolae fringed with ciliate bristles to 1.5cm long. Pedicels to 1.5mm long.

Flowers - Perianth segments 5, pinkish-white, to 2.5mm long, glabrous, obtuse at apex. Stamens +/-5, erect, included. Filaments adnate at base of perianth segments, pinkish to white, to 2mm long, glabrous. Anthers whitish, to .5mm long. Styles 3, connate basally, -1mm long, glabrous. Achenes 3-sided.

Polygonum hydropiperoides flowers

Flowering - June - November.

Habitat - Swamp and pond margins, streambanks, springs, wet woods.

Origin - Native to U.S.

Other info. - This is one of the easier members of the genus to identify. The racemes are distinctive and the plant grows near or in water. The species name means "looks like water pepper" referring to the plants resemblance to the related P. hydropiper L.
P. hydropiperoides grows in most counties throughout the state. Some authors, including Steyermark, break the plant up into different varieties. I won't go into those here.

Photographs taken at the Shawnee Trail Conservation Area, Barton County, MO., 7-28-00.


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