Polygonum FNA Key - Sask

The following key was created as follows:

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Started with key to Polygonum species in the Flora of North America (FNA)

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Removed all species not found in Saskatchewan.  List of Saskatchewan species obtained from Checklist of the Vascular Plants of Saskatchewan by Vernon L. Harms.

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Added rarity/abundance information, also taken from Harms. CC - very common, C - common, FC - fairly common, UC - uncommon, VUL - vulnerable, THR - threatened, END  - endangered, ADV? - possibly adventive, R - rare (applies to introduced species only).

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Added common names.

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Linked species name to species description in Flora of North America

    Stems distinctly and ± regularly 8-16-ribbed; leaf blade venation pinnate, secondary veins conspicuous; anthers whitish yellow; nearly worldwide.  Polygonum section Polygonum
    Stems 4-gonous, ribs obscure or absent; leaf blade venation parallel, secondary veins not conspicuous; anthers pink to purple; mostly w North America.  Polygonum section Duravia

Polygonum section Polygonum

1.  Leaves in distal part of inflorescence reduced, not overtopping flowers (shorter than or equaling flowers); inflorescences axillary and terminal, spikelike.  Polygonum ramosissimum (Bushy Knotweed) C
      Leaves in distal part of inflorescence overtopping flowers; inflorescences entirely axillary.  (2)

2.  Achenes striate-tubercled, uniformly tubercled, or obscurely tubercled.  (3)
     Achenes smooth to roughened (8)

3.  Plants green to bluish green; margins of tepals white, pink, or red.  (4)
     Plants light green or yellowish; margins of tepals green to yellow  (6)

4.  Achenes coarsely striate-tubercled.  Polygonum aviculare (Doorweed) C
     Achenes obscurely tubercled.  (5)

5.  Plants dark brown to black after drying; distal part of ocreae disintegrating into persistent fibers, brown.  Polygonum ramosissimum (Bushy Knotweed) C
      Plants green after drying (sometimes whitish from powdery mildew); distal part of ocreae persistent, silvery.  Polygonum aviculare (Doorweed) C

6.  Perianth tube 40-55% of perianth length; tepals ± keeled; pedicels 1.3-1.8(-2) mm, enclosed in ocreae.  Polygonum achoreum (Striate Knotweed) C
      Perianth tube 20-38% of perianth length; tepals not keeled; pedicels 2-7 mm, exserted from ocreae. (7)

7. Leaf blades elliptic to obovate; distal parts of ocreae ± persistent, silvery; achenes striate-tubercled.  Polygonum erectum (Erect Knotweed) Listed for SK in FNA but reported non-verified by Harms.
      Leaf blades narrowly elliptic to lanceolate, rarely ovate; distal parts of ocreae soon disintegrating into persistent brown fibers; achenes uniformly tubercled.  Polygonum ramosissimum (Bushy Knotweed) C

8. Perianth tube 40-57% of perianth length.  Polygonum aviculare (Doorweed) C
    Perianth tube 18-38% of perianth length.  Polygonum ramosissimum (Bushy Knotweed) C

 

Polygonum section Duravia

1.  Apices of tepals acute to acuminate; achenes light yellow, light brown, or greenish to dark brown, smooth or with longitudinal ridges.  Polygonum polygaloides (Dense Knotweed) THR
     Apices of tepals rounded; achenes black, smooth or minutely tubercled.  (2)

2.  Pedicels reflexed.  Polygonum douglasii (Douglas Knotweed) UC/FC?
     Pedicels erect or erect to spreading.  (3)

3.  Inflorescences dense, cymes ± overlapping at branch tips.  Polygonum spergulariiforme (Spurry Knotweed) END
     Inflorescences elongate, cymes widely spaced along branches.  Polygonum sawatchense (Sawatch Knotweed)  Listed for SK in FNA only.