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1 Flowers in terminal or long-peduncled axillary racemes; branches adnate to stems, therefore appearing to arise internodally; plants suffrutescent bushy herbs |
1 Flowers in small clusters or very reduced racemes of 1-5 flowers, borne in the axils of normally sized or reduced leaves; branches not adnate to the stem, and thus arising at nodes; plants erect or sprawling herbs. |
..2 Stems with 4 obscure ribs or angles (or lacking apparent ribs); leaf venation parallel, with inconspicuous secondary veins, longitudinally plicate; anthers pink-purple |
..2 Stems with 8-16 distinct ribs; leaf venation pinnate, the secondary veins apparent; anthers whitish yellow; [section Polygonum]. |
....3 Perianth bottle-shaped, constricted above the achene. |
......4 Tepals keeled; fruiting perianth divided about 1/3 of its length; stem leaves (1-) avg. 1.6 (-3)× as long as branch leaves |
......4 Tepals not keeled; fruiting perianth divided about ¾ of its length; stem leaves (1.5-) avg. 2.5 (-4)× as long as branch leaves |
....3 Perianth more open, not constricted above the achene. |
........5 Inflorescences spikelike, the cymules borne in the axils of bracts shorter than the cymules |
........5 Inflorescences axillary, the cymules borne in the axils of leaves longer than the cymules (though often shorter than primary leaves of the stem). |
..........6 Ocreae pruinose; mature tepals notably white or pink, loosely spreading; achenes smooth, glossy; [of maritime situations] |
..........6 Ocreae not pruinose; mature tepals yellow-green, white, pink, or reddish, appressed to the achene; achenes either smooth and glossy or textured and dull; [mainly of inland and disturbed situations]; [ P. aviculare complex]. |
............ 7 Outer 3 tepals cucullate, in fruiting condition distinctly surpassing the inner 2 sepals and concealing them. |
............ ..8 Plants prostrate; leaves 2.5-5.6 (-10)× as long as wide |
............ ..8 Plants ascending to erect; leaves 4-12× as long as wide. |
............ ....9 Plants bluish green when fresh, turning dark brown to black when dried; leaves rounded or obtuse at the apex; pedicels 1-2 mm long; stem leaves 1-2.5 (-3.5)× as long as the branch leaves |
............ ....9 Plants yellowish green when fresh, not darkening when dried; leaves acute to acuminate at the apex; pedicels 2.5-6 mm long; stem leaves 2.1-3.5 (-4.2)× as long as the branch leaves |
............ 7 Outer 3 tepals flat, equaling or shorter than the inner 2 sepals. |
............ ......10 Perianth tube 40-57% of the perianth length. |
............ ........11 Tepals green, margins pink or red (rarely white), with branched veins; plants prostrate to ascending, with 3-15 stems; leaf blades 2.8-5.7 (-6.5)× as long as wide |
............ ........11 Tepals green or reddish brown, margins white, with unbranched veins; plants usually ascending, with 1-7 stems; leaf blades (3.40) 4.2-9.2× as long as wide |
............ ......10 Perianth tube 15-40% of the perianth length. |
............ ..........12 Leaf blades 2-4.5× as long as wide; perianth (2.3-) 2.8-4.7 (-5) mm long; achenes (of the early season) (2.1-) 2.7-3.7 mm long |
............ ..........12 Leaf blades (3.4-) 4.2-9.2× as long as wide; perianth 1.9-3.4 mm long; achenes (of the early season) 1.2-1.8 mm long |