Flora of North America species comparison

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Polygonum parryi

Polygonum sect. Duravia

Parry's knotweed, Parry's or prickly knotweed, prickly knotweed
Habit Herbs, compact, often cushion-like. Shrubs, subshrubs, or annual herbs, sometimes compact and cushionlike (in P. parryi, P. hickmanii, and P. heterosepalum), homophyllous, homocarpic, not succulent, not glaucous.
Stems

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

erect or ascending, rarely prostrate, straight or zigzagged, 4-gonous, ribs obscure or absent, smooth or 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.

ocrea 4–8-veined, proximal part not pruinose;

petiole (or blade when petiole absent) articulated or not to ocrea;

blade narrowly linear to subround, rarely coriaceous (P. paronychia, P. shastense, and P. utahense), margins smooth or papillose-denticulate, not rugulose, rarely glaucous adaxially (P. nuttallii); 1-veined or venation parallel (3-veined), secondary veins not conspicuous.
Inflorescences

axillary;

cymes in most axils, 1-flowered.

usually axillary and terminal, sometimes entirely axillary;

cymes 1–6-flowered.
Pedicels

absent.

erect to spreading or reflexed, 0.1–6 mm, sometimes absent.
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, semi-open, or closed;

tepals ± monomorphic, outer tepals equaling or somewhat larger than inner, (dimorphic, with outer tepals shorter than inner in P. heterosepalum), apices of outer tepals rounded or acute to acuminate;

anthers pink to purple (orange-pink in P. hickmanii).
Achenes

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

ovate to elliptic or lanceolate, 3-gonous, shiny or dull, smooth, tubercled, or longitudinally reticulate.

Polygonum parryi

Polygonum sect. Duravia
Phenology Flowering May–July.
Habitat Vernally moist, open, sandy or rocky places
Elevation 500-2000 m (1600-6600 ft)
Distribution
from FNA
CA; WA
[WildflowerSearch map]
[BONAP county map]
Mostly w North America
Discussion

Species 20 (20 in the flora).

Section Duravia is heterogeneous and future studies may reveal the necessity of further subdivision. Seven species referred by J. C. Hickman (1984) to sect. Monticola (Polygonum cascadense, P. heterosepalum, P. hickmanii, P. majus, P. polygaloides, P. sawatchense, and P. utahense) are here included in sect. Duravia based on leaf, anther, achene, and pollen morphology. Heterocarpy does not occur in sect. Duravia.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Key
1. Plants shrubs or subshrubs
→ 2
1. Plants annual herbs
→ 4
2. Stems erect, wiry; perianth 2.6-3.2 mm
P. bolanderi
2. Stems prostrate or ascending, not wiry; perianth (4.5-)5-10 mm
→ 3
3. Ocreae 15-20 mm, distal parts persistent; w coastal dunes
P. paronychia
3. Ocreae 3-5 mm, distal parts deciduous; montane habitats
P. shastense
4. Leaves not articulated to ocreae, blades mostly linear, rarely linear-lanceolate
→ 5
4. Leaves articulated to ocreae, blades subulate, linear-lanceolate to subround
→ 9
5. Distal parts of ocreae entire or shallowly dentate
P. bidwelliae
5. Distal parts of ocreae disintegrating into fibers
→ 6
6. Plants not compact, not cushionlike; stems simple or divaricately branched, 4-40 cm
P. californicum
6. Plants compact, often cushionlike; stems simple or branched from base, 1.5-5(-8) cm
→ 7
7. Distal parts of ocreae with curly fibers
P. parryi
7. Distal parts of ocreae with straight fibers
→ 8
8. Tepals ± monomorphic, outer longer than inner
P. hickmanii
8. Tepals dimorphic, outer shorter than inner
P. heterosepalum
9. Apices of tepals acute to acuminate; achenes light yellow, light brown, or greenish to dark brown, smooth or with longitudinal ridges
P. polygaloides
9. Apices of tepals rounded; achenes black, smooth or minutely tubercled
→ 10
10. Pedicels reflexed
→ 11
10. Pedicels erect or erect to spreading
→ 14
11. Ocreae 5-12 mm; perianths and achenes 3-5 mm
→ 12
11. Ocreae 3-5 mm; perianths and achenes 1.2-2.6 mm
→ 13
12. Flowers open or semi-open; pedicels 0.5-1 mm; perianth tubes 9-17% of perianth lengths
P. majus
12. Flowers closed; pedicels 2-6 mm; perianth tubes 20-28% of perianth lengths
P. douglasii
13. Achenes usually exserted from perianth; leaf blades linear-oblanceolate, margins smooth
P. engelmannii
13. Achenes enclosed in perianth; leaf blades ovate to elliptic or ovate, margins papillose-denticulate
P. austiniae
14. Leaf blades with 1 pleat on each side of midrib
P. tenue
14. Leaf blades without pleats
→ 15
15. Ocreae 4-12 mm, distal parts disintegrating into persistent fibers; perianths (2.8-)3-5 mm; achenes 2.5-5 mm
→ 16
15. Ocreae 1-5 mm, distal parts entire to lacerate; perianths 1.8-2.5 mm; achenes 1.5-2.3 mm
→ 17
16. Inflorescences dense, cymes ± overlapping at branch tips
P. spergulariiforme
16. Inflorescences elongate, cymes widely spaced along branches
P. sawatchense
17. Stems 1.5-3.5 cm; leaf blades with margins revolute, touching along midrib
P. utahense
17. Stems 2-35 cm; leaf blades with margins flat, or if revolute then never touching along midrib
→ 18
18. Flowers open
P. cascadense
18. Flowers semi-open or closed
→ 19
19. Leaf blades narrowly elliptic, elliptic, ovate, obovate, or subround, green adaxially, margins flat
P. minimum
19. Leaf blades linear to narrowly oblong-elliptic, ± glaucous adaxially, margins revolute
P. nuttallii
Source FNA vol. 5, p. 563. FNA vol. 5, p. 561.
Parent taxa Polygonaceae > subfam. Polygonoideae > Polygonum > sect. Duravia Polygonaceae > subfam. Polygonoideae > Polygonum
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
Subordinate taxa
P. austiniae, P. bidwelliae, P. bolanderi, P. californicum, P. cascadense, P. douglasii, P. engelmannii, P. heterosepalum, P. hickmanii, P. majus, P. minimum, P. nuttallii, P. paronychia, P. parryi, P. polygaloides, P. sawatchense, P. shastense, P. spergulariiforme, P. tenue, P. utahense
Synonyms section Duravia, P. section Monticola
Name authority Greene: Bull. Torrey Bot. Club 8: 99. (1881) S. Watson: Amer. Naturalist 7: 665. (1873)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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