Species: Canadanthus modestus (Lindl.) Nesom

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Canadanthus modestus (Lindl.) Nesom

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TAXONOMY

Family:

Asteraceae or Compositae

Genus:

Canadanthus

Species Synonyms:

Weberaster modestus (Lindl.) A. & D. Löve
Aster unalaskensis var. major Hook.
Aster major (Hook.) Porter
Aster modestus Lindl.

Common Names:

large northern aster
giant mountain aster

DISTRIBUTION

Canada:

British Columbia – southern Yukon Territory – Alberta, central Saskatchewan – Ontario

Saskatchewan:

central Saskatchewan; Makwa Lake – Waterhen and Upper Beaver River – southern Lac Ile-a-la-Crosse – Macdowall

Ecoregion:

Boreal Transition, Mid-Boreal Upland

HABITAT

Saskatchewan:

moist, well-drained woods and clearings and roadsides

Associated Species:

Achillea sibirica, Bromus ciliatus, Carex atherodes, Carex aurea, Chamerion angustifolium, Juncus balticus, Larix laricina, Lycopus americanus, Mertensia paniculata, Salix candida

RARITY STATUS

Provincial Status According
to Harms (2003):

Threatened

Nature Conservancy Status:

G5 S2

Saskatchewan Species at
Risk Status:

None

COSEWIC Status:

None

Canadanthus modestus is threatened because it is regionally restricted in Saskatchewan. Local populations are usually large but are limited to localized areas. No immediate threats are known for this species.

SPECIES DESCRIPTION

Height:

30 – 75 cm tall

Roots:

rhizomes fibrous, creeping

Stem:

perennial, branched upwards, very leafy, often purplish, especially at the base, densely villous to glabrate, more so at base

Leaves:

cauline, alternate, sessile to clasping, 4 – 8 cm long, 1 – 2 cm wide, lanceolate, broadest below the middle, base more or less auriculate, apex acute to acuminate, glabrous or hairy, margin entire to distantly serrulate

Inflorescence:

heads several, to 1.5 cm broad, in loose corymbiform, round-topped cluster; peduncles long, leafy-bracted, glandular; phyllaries in 1 – 2 subequal series, 7 – 11 mm high, acuminate, purple to brown to green with brown midvein, glandular

Flowers:

ligulate and tubular; ligulate florets 35 – 50, to 8 mm long, purple; disc florets yellow, pappus single, brownish

Fruits:

achene pubescent

ASTER COMPLEX KEY FOR SPECIES FOUND IN SASKATCHEWAN
*(SPECIES PREVIOUSLY NAMED ASTER)*

1 Basal and lower cauline leaves cordate and petiolate	Symphyotrichum ciliatum
1 Basal and lower cauline leaves tapering at base, sessile to subsessile	2

2 Rays inconspicuous or absent	Symphyotrichum ciliatum (A. brachyactis)
2 Rays conspicuous	3

3 Involucre glandular, sometimes also otherwise pubescent	4
3 Involucre not glandular, but may be pubescent	7

4 Leaves dentate	Eurybia conspicua
4 Leaves entire or nearly so, margins at most strigose pubescent	5

5 Cauline leaves linear, upper sessile (lower petioled)	Almutaster pauciflorus
5 Cauline leaves lanceolate, all sessile to clasping	6

6 Peduncles short; inflorescence compact	Symphyotrichum novae-angliae
6 Peduncles elongate; inflorescence loose	Canadanthus modestus

7 Pappus double	Doellingeria umbellata (var. pubens if leaf puberulent underneath)
7 Pappus single	8

8 Phyllaries with spinulose tips	9
8 Phyllaries without spinulose tips	10

9 Heads small; involucre 2 – 5 mm high, imbricate; rays 10 – 20	Symphyotrichum ericoides var. ericoides
9 Heads larger; involucre 5 – 8 mm high, bracts not strongly imbricate; rays 22-35	Symphyotrichum falcatum var. falcatum

10 Leaves firm; phyllaries hard or firm, coriaceous at base, green-tipped	11
10 Leaves thin and soft; phyllaries thin and scarious, not markedly coriaceous at base	12

11 Plants < 50 cm tall; leaves linear to narrowly oblong	Oligoneuron album
11 Plants 40 – 100 cm tall; leaves ovate to lanceolate	Symphyotrichum laeve var. laeve

12 Stem leaves strongly clasping at base	Symphyotrichum puniceum var. puniceum
12 Stem leaves sessile, scarcely clasping to not at all auriculate clasping (if half clasping, not abruptly contracted to a winged petiole)	13

13 Rays white	Symphyotrichum lanceolatum var. lanceolatum
13 Rays purple or pink, rarely white	14

14 Phyllaries subequal	Symphyotrichum eatonii
14 Phyllaries unequal	15

15 Stems stout, to > 2 m tall; leaves lanceolate to elliptic	Symphyotrichum prenanthoides
15 Stems slender, < 1 m tall; leaves linear to lanceolate	16

16 Leaves firm; involucre appressed	Symphyotrichum adscendens
16 Leaves relatively thin; involucre not appressed	17

17 Leaves mostly 2 – 5 mm wide; heads few (<10)	Symphyotrichum boreale
17 Leaves wider; heads > 10	Symphyotrichum lanceolatum var. hesperium