Burke: Polygonum polygaloides vs. Polygonum fowleri

	Polygonum polygaloides	Polygonum fowleri
		Fowler's knotweed
Habit	Glabrous, erect or ascending, usually freely branched annual 6-20 cm. tall.	Very leafy annual or biennial, the stems prostrate or spreading, freely branched, 1-3 dm. long.
Leaves	Linear, 10-25 mm. long, 1-2 mm. broad, basally jointed; stipules lacerate, 4-8 mm. long.	Leaves alternate, usually overlapping, gradually reduced upward, the short petiole jointed; leaf blades elliptic-linear to elliptic-oblanceolate, rounded, 1.5-3 cm. long and 3-10 mm. wide, firm; stipules sheathing, lacerate, 3-6 mm. long.
Flowers	Crowded in groups of 1-4 on the branch tips, the branches arising from the axils of obovate, prominent, strongly white-margined bracts that have a green mid-rib; perianth 2.5 mm. long, divided over half the length, the 5 segments oblong-lanceolate, with greenish center and prominent white to pink margins.	Flowers in closely packed, short, few-flowered, axillary racemes, exceeded by the bracts; pedicles 1-3 mm. long; the 5 perianth segments 3 mm. long, attached 1/3 their length, greenish with pink margins, oblong; styles 3, very short.
Fruits	Achene with three sharp angles, dark brown, dull, longitudinally striate, 2 mm. long.

	Polygonum polygaloides	Polygonum fowleri
Identification notes		Achene 3-angled, lance-ovoid, olive green to yellowish-brown, smooth and shining.
Flowering time	June-August	July-November
Habitat	Meadows, vernal pools and rocky ridges, lowlands to mid-elevations in the mountains.	Coastal salt marshes.
Distribution	Occurring east of the Cascades crest in Washington; British Columbia to California, east to the Rocky Mountains. [WildflowerSearch map] [BONAP county map]	Occurring west of the Cascades in Washington; Alaska south to California, east across northern Canada to northeastern North America. [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. ramosissimum, P. sawatchense, P. spergulariiforme	P. achoreum, P. austiniae, P. aviculare, P. californicum, P. douglasii, P. erectum, P. majus, P. minimum, P. nuttallii, P. paronychia, P. parryi, P. polygaloides, P. ramosissimum, P. sawatchense, P. spergulariiforme
Subordinate taxa	P. polygaloides ssp. confertiflorum, P. polygaloides ssp. kelloggii, P. polygaloides ssp. polygaloides	P. fowleri ssp. fowleri
Web links	Local floras: BC, CA, OR, WA Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria, Turner Photog. WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search	Local floras: OR, WA Local Web sites: 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 fowleri

Fowler's knotweed

Habit

Glabrous, erect or ascending, usually freely branched annual 6-20 cm. tall.

Very leafy annual or biennial, the stems prostrate or spreading, freely branched, 1-3 dm. long.

Leaves

Linear, 10-25 mm. long, 1-2 mm. broad, basally jointed;

stipules lacerate, 4-8 mm. long.

Leaves alternate, usually overlapping, gradually reduced upward, the short petiole jointed;

leaf blades elliptic-linear to elliptic-oblanceolate, rounded, 1.5-3 cm. long and 3-10 mm. wide, firm;

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

Flowers

Crowded in groups of 1-4 on the branch tips, the branches arising from the axils of obovate, prominent, strongly white-margined bracts that have a green mid-rib;

perianth 2.5 mm. long, divided over half the length, the 5 segments oblong-lanceolate, with greenish center and prominent white to pink margins.

Flowers in closely packed, short, few-flowered, axillary racemes, exceeded by the bracts; pedicles 1-3 mm. long; the 5 perianth segments 3 mm. long, attached 1/3 their length, greenish with pink margins, oblong;

styles 3, very short.

Fruits

Achene with three sharp angles, dark brown, dull, longitudinally striate, 2 mm. long.