FNA: Polygonum cascadense vs. Polygonum sect. Duravia

Phenology

Flowering Jun–Sep.

Habitat

Dry, usually rocky slopes, often on serpentine

Elevation

1600-1800 m (5200-5900 ft)

Distribution

OR

[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