Species: Polygonum polygaloides ssp. confertiflorum (Nutt. ex Piper) Hickman

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Polygonum polygaloides ssp. confertiflorum (Nutt. ex Piper) Hickman

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TAXONOMY

Family:

Polygonaceae

Genus:

Polygonum

Species Synonyms:

Polygonum confertiflorum Nutt. ex Piper
Polygonum imbricatum Nutt.
Polygonum kelloggii var. confertiflorum (Nutt. ex Piper) Dorn
Polygonum watsonii Small

Common Names:

dense-flowered knotweed
Watson’s knotweed
white-margined knotweed

DISTRIBUTION

Canada:

southwestern Saskatchewan

Saskatchewan:

southwestern Saskatchewan; Altawan – Cypress Hills

Ecoregion:

Cypress Upland, Mixed Grassland

HABITAT

Saskatchewan:

moist to dried prairie depressions, slough bottom mudflats, and drying field potholes

Associated Species:

Carex douglasii, Danthonia unispicata, Eleocharis acicularis, Myosurus apetalus var. borealis, Oligoneuron rigidum var. rigidum, Plantago patagonica, Polygonum douglasii, Potentilla gracilis, Psilocarphus elatior, Veronica peregrina

RARITY STATUS

Provincial Status According
to Harms (2003):

Endangered

Nature Conservancy Status:

Saskatchewan Species at
Risk Status:

None

COSEWIC Status:

None

Polygonum polygaloides ssp. confertiflorum is threatened because of rarity in Saskatchewan. Possible threats have been identified for this species.

SPECIES DESCRIPTION

Height:

6 – 20 cm

Stems:

erect, divaricately branched, rarely simple, green, glabrous

Leaves:

basal and cauline, basal leaves often caducous, cauline leaves uniformly distributed, sessile, 10 – 40 mm long, 1 – 2.5 mm wide, narrowly linear, base jointed with petiole, 3-veined, margin revolute; ocrea 4 – 8 mm long, hyaline, 2-lobed, glabrous, veins inconspicuous

Inflorescence:

axillary and terminal, spicate, ovate to cylindrical, flowers 1 – 3 per ocreole

Flowers:

mostly closed; perianth 1.5 – 3 mm long, overlapping, white, pink or red, with conspicuous white margin; stamens 3

Fruits:

achenes brown to dark brown, shiny or dull

POLYGONUM KEY FOR SPECIES FOUND IN SASKATCHEWAN

1 Flowers solitary or in small axillary clusters or open racemes; leaves jointed at the base with the petiole, small; outer tepals may be keeled; ocrea often hyaline, 2-lobed	2
1 Flowers in spicate racemes; leaves not jointed at the base with the petiole, large; outer tepals may be winged or unwinged, but not keeled (except in P. cilinode and P. convolvulus); ocrea chartaceous	9

2 Inflorescence compact	3
2 Inflorescence a slender, open raceme	5

3 Achenes black, smooth and shiny; tepals rounded	P. spergulariiforme
3 Achenes yellowish to dark brown, not shiny; tepals pointed	4

4 Bracts definitely white-margined; stems to 20 cm tall	P. polygaloides var. confertiflorum
4 Bracts only slightly white-margined, if at all; stems less than 20 cm	P. polygaloides var. kelloggii

5 Flowers on reflexed pedicels	P. douglasii ssp. douglasii
5 Flowers ascending or spreading	6

6 Achenes shiny; leaves linear to lanceolate	P. ramosissimum
6 Achenes dull; leaves oval	7

7 Perianth bottle-shaped, outer tepal hooded	P. achoreum
7 Perianth not constricted below the apex, outer tepal not hooded	8

8 Leaves on the branches the same size as the ones attached directly to the stem; calyx with greenish-white or pink margins	P. arenastrum (= P. aviculare ssp. depressum)
8 Leaves on the branches much smaller than the ones attached directly to the stem; calyx with white, pink or purple margins	P. aviculare

9 Stems slender and twining; leaves broad, base hastate	10
9 Stems not twining; leaves linear to lanceolate, base not hastate	12

10 Ocrea with a ring of bristles	P. cilinode (= Fallopia cilinodes)
10 Ocrea lacking bristles	11

11 Fruiting calyx to 5 mm long, wings small; plants annual	P. convolvulus var. convolvulus (= Fallopia convolvulus)
11 Fruiting calyx to 1.5 cm long, wings broad; plants perennial	P. scandens var. scandens (= Fallopia scandens)

12 Leaves mainly basal, cauline leaves few and reduced	P. viviparum (= Bistorta vivipara)
12 Leaves mainly cauline, well-developed	13

13 Ocrea with bristles at the summit	14
13 Ocrea without bristles	15

14 Rhizomes forking; perennials; ocrea expanded at the top to create a flange; spikes to 2 cm thick; perianth not glandular	P. amphibium var. stipulaceum (= Persicaria amphibia)
14 Roots fibrous; ocrea not expanded at the top; spikes slender, less than 2 cm thick; perianth glandular	P. punctatum var. confertiflorum (= Persicaria punctata)

15 Annuals, terrestrial; roots fibrous; spikes terminal and axillary, numerous	P. lapathifolium var. lapathifolium (= Persicaria lapathifolia)
15 Perennials, often aquatic; rhizomes forking; spikes terminal, solitary or paired	16

16 Petioles attached near base of ocrea; leaves and upper stems glabrous to sparsely strigose	P. coccineum var. coccineum (= Persicaria amphibia)
16 Petioles attached midway on ocrea; leaves and upper stems densely ashy-gray pubescent	P. coccineum var. pratincola (= Persicaria amphibia)