Polygonum persicaria L.
Family - Polygonaceae
Stems - To -1m tall, glabrous, branching at base, erect, herbaceous, from taproot, typically reddish at
nodes.
Leaves - Alternate, lanceolate
to linear lanceolate, short-petiolate to sessile above, to +11cm long,
+/-2cm broad, glabrous to sparse appressed pubescent, typically with purple
splotch near middle of blade, entire. Ocrea appressed pubescent friged
with cilia. Petioles to 6mm long, red, sparse appressed antrorse pubescent.
Young plant.
Leaves.
Inflorescence - Terminal and axillary racemes +3cm long, +/-1cm in diameter, dense. Bracts subtending flowers (ocreolae) with or without short cilia (-1mm) at summit.
Flowers - Perianth pink to
rose or typically whitish at anthesis, to 3.5mm long. Perianth parts glabrous,
ovate to orbicular. Stamens 5, 1.7mm long, white, glabrous, adnate to base
of perianth parts. Anthers pale yellow to white, .1mm broad. Styles typically
2, .8mm long, white, glabrous. Achenes typically 2-sided, black, shiny,
to +/-2mm long.
Flowering - May - October.
Habitat - Moist to wet waste ground, disturbed sites, meadows, streambanks, roadsides, railroads.
Origin - Native to Europe.
Other info. - This species
is recognized by the characteristic purple splotch in the center of the
leaf. The spot is not always present but typically is. The perianth is
somewhat variable in color.
The plant is common in the habitats
mentioned above and is somewhat toxic.
This species somewhat resembles
P. cespitosum Bl. but the latter has a more rose-colored perianth
and the bracts of the inflorescence have cilia which typically are longer
than the flowers.
Photographs taken at the Kansas City Zoo, 5-30-99 and 5-11-00.
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