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Parry's knotweed, Parry's or prickly knotweed, prickly knotweed

Utah knotweed

Habit Herbs, compact, often cushion-like. Herbs.
Stems

erect, green-brown, simple or branched from base, not wiry, 2–5(–8) cm, glabrous.

erect, green, simple or with few branches, not wiry, 1.5–3.5 cm, papillose-scabridulous.

Leaves

± uniformly distributed, dense, not articulated to ocreae, basal leaves ± persistent, distal leaves gradually reduced to bracts;

ocrea 2–4(–5) mm, glabrous, proximal part cylindric, distal part deeply lacerate, disintegrating into white, curled fibers;

petiole absent;

blade 3-veined, without pleats, linear-lanceolate, subulate, 5–13(–20) × 0.4–1 mm, margins revolute, smooth, apex spine-tipped.

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

ocrea 2–3.5 mm, papillose-scabridulous, proximal part funnelform, distal part hyaline, lacerate;

petiole absent;

blade 1-veined, not pleated, linear-subulate, 6–14 × 1 mm, coriaceous, margins revolute, touching along midrib, apex acute, mucronate, papillose.

Inflorescences

axillary;

cymes in most axils, 1-flowered.

axillary and terminal, spikelike, dense;

cymes overlapping, starting almost from stem base, 2–4-flowered.

Pedicels

absent.

enclosed in ocreae, erect to spreading, 0.4–1 mm.

Flowers

closed;

perianth 1.5–2(–2.5) mm;

tube 6–15% of perianth length;

tepals overlapping, usually reddish with white margins, petaloid, oblong, navicular, apex acute;

midveins unbranched;

stamens 8.

open;

perianth 2–2.5 mm;

tube 20–25% of perianth length;

tepals overlapping, uniformly white, petaloid, oblong to widely obovate, cucullate, navicular in distal 1/4, apex rounded;

midveins branched;

stamens 8.

Achenes

slightly exserted from perianth at maturity, dark brown, ovate, 1.2–1.6(–2) mm, faces subequal, shiny, smooth.

enclosed in perianth, black, elliptic, 1.5–2 mm, faces subequal, shiny, smooth.

Polygonum parryi

Polygonum utahense

Phenology Flowering May–July. Flowering Jul–Sep.
Habitat Vernally moist, open, sandy or rocky places Dry, sandy ravines, rocky Navajo sandstone spur
Elevation 500-2000 m (1600-6600 ft) 2300 m (7500 ft)
Distribution
from FNA
CA; WA
[WildflowerSearch map]
[BONAP county map]
from FNA
UT
[BONAP county map]
Discussion

Polygonum utahense has been treated as a synonym of P. sawatchense by some authors (e.g., S. L. Welsh et al. 1987; J. T. Kartesz and C. A. Meacham 1999). Its perianth morphology suggests a relationship with P. cascadense, from which it differs in its dwarf habit and uniformly papillose leaves with margins revolute, touching along midribs.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 5, p. 563. FNA vol. 5, p. 571.
Parent taxa Polygonaceae > subfam. Polygonoideae > Polygonum > sect. Duravia Polygonaceae > subfam. Polygonoideae > Polygonum > sect. Duravia
Sibling taxa
P. achoreum, P. argyrocoleon, P. austiniae, 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. patulum, P. plebeium, P. polygaloides, P. ramosissimum, P. sawatchense, P. shastense, P. spergulariiforme, P. striatulum, P. tenue, P. utahense
P. achoreum, P. argyrocoleon, P. austiniae, 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
Synonyms P. douglasii var. utahense
Name authority Greene: Bull. Torrey Bot. Club 8: 99. (1881) Brenckle & Cottam: Bull. Univ. Utah, Biol. Ser. 4(4): 3, plate 1. (1940)
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