Wildflowers of Southern Arizona
Prostrate Knotweed.
Polygonum aviculare.
Buckwheat (Polygonaceae) family.
Plants green or bluish green, green after drying, sometimes whitish from powdery mildew, homophyllous or heterophyllous. Stems prostrate to erect, branched, flexuous, 5-200 cm. Leaves: ocrea 3-15 mm, proximal part cylindric or ± funnelform, distal part silvery, hyaline, soon disintegrating into persistent fibers or nearly completely deciduous; petiole 0.3-9 mm; blade green to gray-green, narrowly elliptic, lanceolate, elliptic, obovate, or spatulate, 6-50(-60) × 0.5-22 mm, margins flat, apex acute, obtuse, or rounded; stem leaves 1-4 times as long as adjacent branch leaves; distal leaves overtopping flowers. Inflorescences axillary; cymes uniformly distributed or aggregated at tips of stems and branches, 1-6(-8)-flowered. Pedicels enclosed in or exserted from ocreae, 1.5-5 mm. Flowers closed or semi-open; perianth 1.8-5.5 mm; tube 20-57% of perianth length; tepals overlapping or not, green or reddish brown with white, pink, or red margins, petaloid, not keeled, oblong to obovate, often cucullate in fruit; midveins branched or unbranched, thickened or not; stamens 5-8. Achenes enclosed in or exserted from perianth, light to dark brown, ovate, (2-)3-gonous, 1.2-4.2 mm, faces subequal or unequal, apex not beaked, edges slightly concave, dull, usually coarsely striate-tubercled, sometimes obscurely tubercled; late-season achenes common or not, 2-5 mm.
Santa Catalina Mountains.
Location: Parking lot next to Oracle Ridge Trailhead.
7/30/15
Notes: Non-native.
See SEINet Pictures and Description