Burke: Polygonum aviculare vs. Polygonum fowleri

	Polygonum aviculare	Polygonum fowleri
		Fowler's knotweed
Habit	Highly variable species, prostrate and spreading (but not rooting at the nodes) to occasionally erect, freely-branched annual, the stems terete, striate, up to 1 m. long.	Very leafy annual or biennial, the stems prostrate or spreading, freely branched, 1-3 dm. long.
Leaves	Numerous, bluish-green, only slightly reduced upward, narrowly oblong, 1-3 cm. long and 2-6 mm. broad, narrowed to a very short, jointed petiole; stipules lacerate, 3-6 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	1-3 in the axils of the leaves or leaf-like bracts, the pedicles 1-3 mm. long, erect; perianth 2.5 mm. long, divided 2/3 the length, the segments 5, oblong, sub-equal, greenish with white to pink or red 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 3 sharp angles, brownish, smooth.

	Polygonum aviculare	Polygonum fowleri
Identification notes		Achene 3-angled, lance-ovoid, olive green to yellowish-brown, smooth and shining.
Flowering time	May-October	July-November
Habitat	Dry or slightly moist, disturbed soil, often where hard-packed.	Coastal salt marshes.
Distribution	Occurring on both sides of the Cascades crest in Washington; Alaska to California, east across North America to the Atlantic Coast. [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	Both native and introduced	Native
Conservation status	Not of concern	Not of concern
Sibling taxa	P. achoreum, P. austiniae, P. californicum, P. douglasii, P. erectum, P. fowleri, P. majus, P. minimum, P. nuttallii, P. paronychia, P. parryi, P. polygaloides, 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. aviculare ssp. aviculare, P. aviculare ssp. buxiforme, P. aviculare ssp. depressum, P. aviculare ssp. neglectum	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

Highly variable species, prostrate and spreading (but not rooting at the nodes) to occasionally erect, freely-branched annual, the stems terete, striate, up to 1 m. long.

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

Leaves

Numerous, bluish-green, only slightly reduced upward, narrowly oblong, 1-3 cm. long and 2-6 mm. broad, narrowed to a very short, jointed petiole;

stipules lacerate, 3-6 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

1-3 in the axils of the leaves or leaf-like bracts, the pedicles 1-3 mm. long, erect;

perianth 2.5 mm. long, divided 2/3 the length, the segments 5, oblong, sub-equal, greenish with white to pink or red 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 3 sharp angles, brownish, smooth.