Polygonum cascadense |
Polygonum oxyspermum |
|||||
---|---|---|---|---|---|---|
Cascade knotweed |
knotweed, sharp-fruit knotweed |
|||||
Habit | Herbs. | Plants green to blue-green, homophyllous. | ||||
Stems | spreading to erect, zigzagged, green, simple or branched from base, wiry, 5–12(–15) cm, glabrous. |
prostrate to ascending, branched at proximal and middle nodes, not wiry, 20–100 cm. |
||||
Leaves | uniformly distributed, articulated to ocreae, basal leaves persistent, distal leaves abruptly reduced to bracts; ocrea 2–5 mm, glabrous, proximal part funnelform, distal part lacerate; petiole essentially absent; blade 1-veined, not pleated, oblanceolate to obovate, 5–20 × 2–5 mm, margins revolute, never touching along midrib, sparsely papillose-denticulate, apex rounded or apiculate. |
ocrea 6.5–12 mm, proximal part cylindric, pruinose, distal part hyaline, soon disintegrating into brown fibers or nearly completely deciduous; petiole 0–1 mm; blade green to bluish green, elliptic-lanceolate to linear, 10–35 × 1.5–15 mm, margins flat or narrowly revolute, apex acute; middle stem leaves slightly larger than adjacent branch leaves, distal leaves overtopping flowers. |
||||
Inflorescences | axillary and terminal, spikelike, dense; cymes congested at tips of stems and branches, 3–5-flowered. |
axillary, cymes uniformly distributed, 2–7-flowered. |
||||
Pedicels | enclosed in ocreae, erect to spreading, 2–3 mm. |
exserted from ocreae, 2.5–5(–7) mm. |
||||
Flowers | open; perianth 2–2.5 mm; tube 12–25% of perianth length; tepals overlapping, uniformly white, petaloid, oblong to obovate, cucullate, navicular in distal 1/4, apex rounded; midveins unbranched; stamens 8. |
semi-open; perianth 3.5–5.5 mm; tube 28–39% of perianth length; tepals slightly overlapping, green, margins white to pink, petaloid, not keeled, oblong to obovate, not cucullate; veins branched; stamens 8. |
||||
Achenes | enclosed in or exserted from perianth, black, ovate to ovate-oblong, 1.8–2.1 mm, faces subequal, shiny, smooth. |
exserted from perianth, pale brown to dark brown, ovate, 3-gonous, (3.5–)4.1–5.5(–6.5) mm, faces subequal, apex not beaked, edges straight, shiny, smooth or with fine tubercles especially toward apex; late-season achenes unknown. |
||||
Polygonum cascadense |
Polygonum oxyspermum |
|||||
Phenology | Flowering Jun–Sep. | |||||
Habitat | Dry, usually rocky slopes, often on serpentine | |||||
Elevation | 1600-1800 m (5200-5900 ft) | |||||
Distribution |
OR
|
ME; NB; NF; NS; PE; QC; Europe |
||||
Discussion | Subspecies 3 (2 in the flora). The treatment by D. A. Webb and A. O. Chater (1963) of the Polygonum oxyspermum complex is followed here. T. Karlsson (2000) accepted P. raii and P. oxyspermum as distinct species. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
|||||
Key |
|
|||||
Source | FNA vol. 5, p. 571. | FNA vol. 5, p. 554. | ||||
Parent taxa | Polygonaceae > subfam. Polygonoideae > Polygonum > sect. Duravia | Polygonaceae > subfam. Polygonoideae > Polygonum > sect. Polygonum | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Name authority | W. H. Baker: Madroño 10: 62, plate 1, fig. 1. (1949) | C. A. Meyer & Bunge ex Ledebour: Index Seminum (Dorpat) 1824: 5. (1824) | ||||
Web links |