Flora of the Canadian Arctic Archipelago

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S.G. Aiken, M.J. Dallwitz, L.L. Consaul, C.L. McJannet, R.L. Boles, G.W. Argus, J.M. Gillett, P.J. Scott, R. Elven, M.C. LeBlanc, L.J. Gillespie, A.K. Brysting, H. Solstad, and J.G. Harris

Erigeron porsildii G.L. Nesom and D.F. Murray

Asteraceae (Compositae), Daisy family.

Published in Sida 21: 44. 2004.

Type: Canada. N.W.T.: Victoria Island, southwestern coast, vicinity of Holman Island trading post, dry, gravelly slope, 8 Aug 1949, A.E. Porsild 17342. colour image!, photos in Porsild 1955!; Holotype: CAN!. Isotype:: ALA!.

Synonymy. Erigeron grandiflorus Hooker subsp. arcticus A.E.Porsild, Naturaliste Canad., Bot. 4: 67. 1975.

Non Erigeron arcticus Rouy, Fl. France, 8:160. 1903.

Vegetative morphology. Plants 10–15(–25) cm high; perennial herbs. Taproot present, or only fibrous roots present (fibrous brown roots developed off a blackish caudex). Ground level or underground stems horizontal, or vertical; elongate, or compact; (0.3–)4–7 mm wide. Caudex present. Aerial stems erect. Leaves present; heterophyllous (slighlty, basal oblong-oblanceolate to narrowly obovate; cauline leaves oblong-lanceolate to lanceolate); mainly basal and distributed along the stems; patent; alternate; dying annually and non-persistent. Petioles present (some lower leaves), or absent (most leaves); 2–20 mm long (if applicable); winged (but sub-clasping at the base); hairy; villous. Petiole hairs shorter than the diameter of the petiole, or longer than the diameter of the petiole (0.5–1.6 mm long, usually stipate glandular); spreading; floccose, or wavy. Leaf blades simple. Leaf blade bases attenuate. Blades 50–90 mm long (-130 mm long CAN 418879; 20–35 mm long on flowering stem), 4–8(–10) mm wide, spreading, oblanceolate, flat, veins palmate or appearing single-veined. Blade adaxial surface hairy, hairs villous, hairs simple (multicellular), hairs sparse or moderately dense, hairs white, or translucent. Blade abaxial surface hairy, hairs villous (coarsely), hairs sparse or moderately dense, hairs white, hairs wavy, hairs appressed or spreading. Blade margins entire, with glandular hairs; apices acute, or obtuse.

Reproductive morphology. Flowering stems with leaves. Flowering stems hairy. Flowering stems villous. Flowering stem hairs simple; shorter than the diameter of the flowering stem (usually), or longer than the diameter of the flowering stem; white or translucent. Inflorescences solitary heads; terminal. Flowering heads 6–12(–18) mm deep; 12–20(–30) mm wide; with disc and ray florets. Involucral bracts present. Number of rows 1–2. Outer involucral bracts mostly wine red or purple pigmented; lying adjacent to the flowers; lanceolate; 4–4.5 mm high; 0.5–0.9 mm wide; densely hairy (with white to grey villous hairs); without glandular hairs. Inner involucral bracts linear; 6.5–7.5 mm high; 0.7–0.9 mm wide (slightly longer and less hairy than the outer bracts); margins narrow and scarious, less than one quarter of the bract; apex lacerate (and hairy). Flowers radially symmetrical (actinomorphic) (disc florets), or bilaterally symmetrical (zygomorphic) (ray florets); unisexual (ray florets), or bisexual (disc florets). Sepals represented by a pappus. Pappus with a single row of hairs (14–20(-25) bristles, with a prominent outer series of setae or narrow scales); yellowish. Ray florets pappus 3.5–4 mm long. Disc florets pappus 3.5–3.5 mm long. Petals conventional; fused; 5; white, or purple, or blue (ray florets pale lavender drying yellow; disc florets with lavender tips to the petals), or yellow (disc florets); with contrasting markings (darker on the tips and pale towards the base), or without contrasting markings (weakly coiling); 3.8–4.5 mm long (puberulent with glandular hairs, throat not indurate or inflated (6–7 mm, Aiken)). Corolla tubular, or funnel-form (disc florets), or flat, strap-like (ray florets); 2-lobed, or 3-lobed (faintly, ray florets), or 5-lobed (with distinct tips, disc florets). Ray florets 65–110(–130); limb 13–17 mm long; limb 1.5–2 mm wide (when fresh, rolled after drying to 0.3 mm wide). Stamens 5. Anthers yellow; 1.2–1.3 mm long. Ovary inferior; carpels 2; syncarpous. Styles 1; 4.5–5 mm long. Stigmas per ovary 2. Placentation basal. Ovules per ovary 1. Fruit sessile; with calyx persisting; dry; cypselas; yellowish; 2–2.5 mm long; 0.7–1 mm wide; hairy; surface 2 veins visible; indehiscent. Cypselas surface sparsely strigose. Seeds 1.

Chromosome information. 2n = 18.

2n = 18. Zhukova (1965b, Wrangel Island; 1969, northeastern Asia; 1980, southern Chukotka, all as 'komarovii'); Zhukova et al. (1973, north and northeastern Asia, as 'komarovii'); Rostovtseva and Nechayev (1981, Siberia, as E. koraginensis). Dawe and Murray (1986, Alaska).

Ploidy levels recorded 2x.

Ecology and habitat. Elevation 1200 m (CAN 313078). Substrates: tundra, slopes, dry meadows; dry; rocks, gravel (shale); calcareous. Southwestern exposure on 40% slope of lichens and mosses (CAN 313078). Yukon: alpine meadows, in a Kobresia myosuroides turf on a ridge crest (CAN 454241).

North American distribution. Alaska, Yukon, Northwest Territories Islands, continental Northwest Territories. Range in the Canadian Arctic Archipelago limited. Rare. Low Arctic, alpine. Arctic islands: Victoria (one record from Holman (CAN 128163) as subsp. arcticus; dry rocky slope).

Northern hemisphere distribution. North American. North Alaska – Yukon, Central Canada.

General notes. Erigeron porsildii is an arctic member of a complicated and at least partly agamospermic E. grandiflorus complex. (Stephen Spongberg 1970, on annotation label, CAN 103839.). This complex comprises the Cordilleran E. grandiflorus Hook., the local Alaskan and N Yukon E. muirii A. Gray, the NE Asian E. koraginensis (Kom.) Botsch. (incl. E. komarovii Botsch.), several other E Asian Pacific species, and the arctic E. porsildii, the only entity found in the Flora region. The relationships among these, which are now all considered as species, are discussed by Nesom and Murray (2004).

Porsild and Cody (1980) recognised only one entity in continental NWT as E. grandiflorus subsp. arcticus (=E. porsildii). As seen from their map, this entity excluded 'muirii' but included all other northern plants of E. grandiflorus in NWT, Yukon Territory, and Alaska, both the northern Cordilleran ones and the Arctic coastal plants west to Mackenzie River (but not Herschel Island). This view was also reflected by Cody (1996) who recognised E. muirii as a separate species, in Canada only known from Herschel Island, whereas E. grandiflorus subsp. arcticus in Yukon reaches north to the Richardson Mountains. Also Cody, as late as 1996, considered both entities as purely North American. This is also confirmed by Nesom and Murray (2004); P. porsildii and P. muirii are both accepted as species.

Nesom and Murray (2004) were aware of this discussion and noted that it has not been clear whether E. koraginensis occurs on the North America continent or whether it might be conspecific with an earlier-named American species, particularly E. grandiflorus. Erigeron koraginensis and E. porsildii are the most similar among these species, but here, based on material housed at ALA, these authors concluded that E. koraginensis and E. porsildii are distinct and noted that they had seen no collections of E. koraginensis from North America.

They provided the following key to distinguish these taxa.

" 1. Leaves sparsely to moderately villous on both surfaces; villous involucral vestiture of whitish hairs, without coloured cross-walls; ray florets 65–110, corollas 13–17 mm long; disc corollas 3.8–4.5 mm long; outer pappus a prominent series of long setae or scales ... Erigeron porsildii

1. Leaves glabrous or essentially so on adaxial surfaces, villous abaxially; villous involucral vestiture of hairs with purple cross-walls; ray florets 45–73, corollas 9–13 mm long; disc corollas 3–3.9 mm long, outer pappus of a few minute setae and narrow scales ... Erigeron koraginensis " (p. 46)

Illustrations. • Pressed specimen from Arctic islands. Holotype specimen of Erigeron porsildii (as E. grandiflorus subsp. arcticus) Victoria Island. A.E. Porsild 17342. CAN 226845. • Arctic Island Distribution.


This publication is available on the internet (posted May 2011) and on CD-ROM (published in 2007). These versions are identical in content, except that the errata page for CD-ROM is accessible on the main index page of the web version.

Recommended citation for the web-based version of this publication: Aiken, S.G., Dallwitz, M.J., Consaul, L.L., McJannet, C.L., Boles, R.L., Argus, G.W., Gillett, J.M., Scott, P.J., Elven, R., LeBlanc, M.C., Gillespie, L.J., Brysting, A.K., Solstad, H., and Harris, J.G. 2007. Flora of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval. NRC Research Press, National Research Council of Canada, Ottawa. http://nature.ca/aaflora/data, accessed on DATE.

Recommended citation for the CD-ROM version of this publication: Aiken, S.G., Dallwitz, M.J., Consaul, L.L., McJannet, C.L., Boles, R.L., Argus, G.W., Gillett, J.M., Scott, P.J., Elven, R., LeBlanc, M.C., Gillespie, L.J., Brysting, A.K., Solstad, H., and Harris, J.G. 2007. Flora of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval. [CD-ROM] NRC Research Press, National Research Council of Canada, Ottawa.

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