Burke: Polygonum ramosissimum vs. Polygonum spergulariiforme

	Polygonum ramosissimum	Polygonum spergulariiforme
		fall knotweed, spurry knotweed
Habit		Erect to rounded annual, the stems simple or freely-branched, up to 5 dm. tall, the branches wiry, sharply angled above.
Leaves		Leaves alternate, basally jointed, linear to narrowly oblong-oblanceolate, 1-3 cm. long and 1-2 mm. wide; stipules sheathing, lacerate, 3-6 mm. long.
Flowers		Flowers 1-4 in the axils of the upper leaves and crowded, leaf-like bracts which exceed the flowers; pedicles slender, 1-2 mm. long; the 5 perianth segments 3-4 mm. long, attached 1/3 their length, pinkish with a green midrib; stamens 8; styles 3, 0.5 mm. long.
Fruits		Achene 3-angled, 3-4 mm. long, black, shining and smooth.

	Polygonum ramosissimum	Polygonum spergulariiforme
Flowering time	July-September	June-September
Habitat	Disturbed areas, often where wet, from low to middle elevations.	Balds, prairies, and headlands in gravelly, sandy or heavy, dry or moist soil at low elevations.
Distribution	Occurring chiefly east of the Cascades crest in Washington; widely distributed throughout North America. [WildflowerSearch map] [BONAP county map]	Occurring west of the Cascades crest and east in the Columbia River Gorge in Washington; British Columbia to California, east to Idaho, Montana, and Wyoming. [WildflowerSearch map] [BONAP county map]
Origin	Native	Native
Conservation status	Not of concern	Not of concern
Sibling taxa	P. achoreum, P. austiniae, P. aviculare, P. californicum, P. douglasii, P. erectum, P. fowleri, P. majus, P. minimum, P. nuttallii, P. paronychia, P. parryi, P. polygaloides, P. sawatchense, P. spergulariiforme	P. achoreum, P. austiniae, P. aviculare, P. californicum, P. douglasii, P. erectum, P. fowleri, P. majus, P. minimum, P. nuttallii, P. paronychia, P. parryi, P. polygaloides, P. ramosissimum, P. sawatchense
Subordinate taxa	P. ramosissimum ssp. prolificum, P. ramosissimum ssp. ramosissimum
Web links	Local floras: CA, OR, WA Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search	Local floras: BC, CA, OR, WA Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Polygonum spergulariiforme

fall knotweed, spurry knotweed

Habit

Erect to rounded annual, the stems simple or freely-branched, up to 5 dm. tall, the branches wiry, sharply angled above.

Leaves

Leaves alternate, basally jointed, linear to narrowly oblong-oblanceolate, 1-3 cm. long and 1-2 mm. wide;

stipules sheathing, lacerate, 3-6 mm. long.

Flowers

Flowers 1-4 in the axils of the upper leaves and crowded, leaf-like bracts which exceed the flowers; pedicles slender, 1-2 mm. long; the 5 perianth segments 3-4 mm. long, attached 1/3 their length, pinkish with a green midrib;

stamens 8;

styles 3, 0.5 mm. long.

Fruits

Achene 3-angled, 3-4 mm. long, black, shining and smooth.

Polygonum ramosissimum

Polygonum spergulariiforme

Flowering time

July-September

June-September

Habitat

Disturbed areas, often where wet, from low to middle elevations.

Balds, prairies, and headlands in gravelly, sandy or heavy, dry or moist soil at low elevations.

Distribution

Occurring chiefly east of the Cascades crest in Washington; widely distributed throughout North America.

[WildflowerSearch map]

[BONAP county map]

Occurring west of the Cascades crest and east in the Columbia River Gorge in Washington; British Columbia to California, east to Idaho, Montana, and Wyoming.

[WildflowerSearch map]

[BONAP county map]

Origin

Native

Conservation status

Not of concern

Sibling taxa