Polygonum minimum |
Polygonum engelmannii |
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broad-leaf knotweed, broad-leaf or leafy dwarf knotweed, leafy dwarf knotweed, little mountain knotweed, zigzag knotweed |
Engelmann's knotweed |
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Habit | Herbs. | Herbs. |
Stems | prostrate to erect, often zigzagged, reddish brown, simple or branched from base, wiry, 2–30 cm, papillose-scabrid-ulous. |
erect, green or purplish brown, branched from base, not wiry, 4–30 cm, glabrous or minutely papillose-scabridulous. |
Leaves | evenly distributed or crowded at branch tips, articulated to ocreae, basal leaves persistent, hardly reduced distally; ocrea 1–4 mm, papillose-scabridulous, proximal part cylindric, distal part entire or dentate-lacerate; petiole 0.1–3 mm; blade 1-veined, not pleated, narrowly elliptic, elliptic, ovate, obovate, or subround, 6–27 × 3–8 mm, margins flat, smooth, irregularly thickened or papillose-denticulate, apex apiculate, green adaxially. |
uniformly distributed, articulated to ocreae, basal leaves persistent, distal leaves abruptly reduced to bracts; ocrea 3–5 mm, papillose-scabridulous or glabrous, proximal part funnelform, distal part becoming lacerate with age; petiole 0.1–2 mm; blade 1-veined, not pleated, linear-oblanceolate, 10–20(–25) × 1–3(–4) mm, margins revolute, smooth, apex acute to mucronate. |
Inflorescences | axillary; cymes from near stem and branch bases, sometimes also crowded at branch apices, 1–3-flowered. |
axillary and terminal, spikelike, loosely floriferous nearly to base, elongate; cymes spaced along branches, (1–)2–4-flowered. |
Pedicels | enclosed in ocreae, erect to spreading, 2–3 mm. |
exserted from ocreae, reflexed, 1–3 mm. |
Flowers | semi-open or closed; perianth 1.8–2.5 mm; tube 22–29% of perianth length; tepals overlapping, greenish with narrow white or pink margins, almost sepaloid, oblong, cucullate, ± navicular, apex rounded; midveins thickened, unbranched; stamens 8. |
closed; perianth 1.5–2(–2.5) mm; tube 18–26% of perianth length; tepals initially overlapping and cucullate, later forced apart by developing achene, greenish or sometimes purple, with white margins, petaloid or sepaloid, oblong, ± flat or navicular, apex rounded; midveins unbranched; stamens 5–8. |
Achenes | enclosed in perianth or tip exserted, black, elliptic to ovate, 1.8–2.3 mm, faces subequal, smooth, shiny. |
exserted from perianth, black, elliptic, 1.2–2.3 mm, faces subequal, shiny, smooth. |
Polygonum minimum |
Polygonum engelmannii |
|
Phenology | Flowering Jul–Sep. | Flowering Jun–Sep. |
Habitat | Alpine to subalpine sites, open or semibarren soil | Dry to moist sandy or well-drained soils, sagebrush desert to lower mountains |
Elevation | 1500-3300 m (4900-10800 ft) | 1000-1500 m (3300-4900 ft) |
Distribution |
AK; CA; CO; ID; MT; NV; OR; UT; WA; WY; AB; BC
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CO; ID; MT; NV; SD; UT; WY; AB; BC |
Source | FNA vol. 5, p. 569. | FNA vol. 5, p. 569. |
Parent taxa | Polygonaceae > subfam. Polygonoideae > Polygonum > sect. Duravia | Polygonaceae > subfam. Polygonoideae > Polygonum > sect. Duravia |
Sibling taxa | ||
Synonyms | P. torreyi | P. douglasii subsp. engelmannii |
Name authority | S. Watson: Botany (Fortieth Parallel), 315. (1871) | Greene: Bull. Calif. Acad. Sci. 1: 126. (1885) |
Web links |
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