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Austin's knotweed, Mrs. Austin's knotweed, Rebecca Austin's knotweed

Habit Herbs.
Stems

ascending to erect, green to purplish, much-branched from base, not wiry, 5–10(–20) cm, papillose-scabridulous.

Leaves

uniformly distributed, articulated to ocreae, basal leaves persistent, distal leaves abruptly reduced to bracts, articulated to ocreae;

ocrea 3–5 mm, papillose-scabridulous or glabrous, proximal part funnelform, distal part lacerate;

petiole 0.1–2 mm;

blade 1-veined, not pleated, ovate to elliptic or obovate, 5–15 × 4–7 mm, margins flat or narrowly revolute, papillose-denticulate, apex acute or mucronate.

Inflorescences

axillary and terminal, spikelike, slender;

cymes spaced along branches, 1–4-flowered.

Pedicels

exserted from ocreae, reflexed, 1–2.5 mm.

Flowers

closed;

perianth (1.8–)2–2.6 mm;

tube 20–28% of perianth length;

tepals overlapping, green or purple, with narrow whitish margins, petaloid or sepaloid, oblong, cucullate, navicular, apex rounded;

midveins unbranched;

stamens 8.

Achenes

enclosed in perianth, black, elliptic to obovate, 2–2.5 mm, faces subequal, shiny, ± smooth.

Polygonum austiniae

Phenology Flowering Jun–Sep.
Habitat Dry to moist flats on banks, sagebrush plains, and ponderosa pine forests
Elevation 1300-1600 m (4300-5200 ft)
Distribution
from FNA
CA; ID; MT; NV; OR; WA; WY; AB; BC
[WildflowerSearch map]
[BONAP county map]
Source FNA vol. 5, p. 569.
Parent taxa Polygonaceae > subfam. Polygonoideae > Polygonum > sect. Duravia
Sibling taxa
P. achoreum, P. argyrocoleon, P. aviculare, P. bidwelliae, P. bolanderi, P. californicum, P. cascadense, P. douglasii, P. engelmannii, P. erectum, P. fowleri, P. glaucum, P. heterosepalum, P. hickmanii, P. humifusum, P. majus, P. marinense, P. minimum, P. nuttallii, P. oxyspermum, P. paronychia, P. parryi, P. patulum, P. plebeium, P. polygaloides, P. ramosissimum, P. sawatchense, P. shastense, P. spergulariiforme, P. striatulum, P. tenue, P. utahense
Synonyms P. douglasii subsp. austiniae
Name authority Greene: Bull. Calif. Acad. Sci. 1: 212. (1885)
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