Flora of the Canadian Arctic Archipelago


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 humilis Graham

English: Low fleabane,

French: Petit evergerette,

Inuktitut: Nunaraqpait.

Asteraceae (Compositae), Daisy family.

Published in Edinburgh New Philos. J. 6: 175. 1823.

Type: Described from garden plants of seeds from the Canadian Arctic, collected by Richardson.

Synonymy. Erigeron unalaschkensis (DC.) Vierhapper, Beih. Bot. Centralbl. 19: 492. 1906.

Erigeron uniflorus L. var. unalaschkensis Ostenf. Meddel. Grønland 64: 242. 1923.

Erigeron uniflorus L. var. unalaschkensis (DC.) B. Boivin, Phytologia, 23: 49. 1972.

Erigeron uniflorus L. subsp. eriocephalus (J.Vahl ex Hornem) Cronquist, Brittonia 6: 236. 1947.

Vegetative morphology. Plants 2–15 cm high; perennial herbs; caespitose. Taproot present, or only fibrous roots present (fibrous roots developed from the caudex). Ground level or underground stems vertical. Caudex present (short). Aerial stems erect. Leaves mainly basal; erect; alternate; dying annually and non-persistent, or marcescent. Petioles present (in some basal leaves), or absent (most leaves); 0.5–1.5 mm long (if applicable); hairy; pilose. Petiole hairs shorter than the diameter of the petiole; spreading, or erect; curved. Leaf blades simple. Leaf blade bases attenuate. Blades 8–50 mm long, 2–4 mm wide, spreading, obovate, flat, veins pinnate or appearing single-veined. Blade adaxial surface glabrous or hairy, hairs pilose (if applicable), hairs simple, hairs sparse (if applicable), hairs a mixture of white and yellow hairs (towards the base of the leaf) or multicellular with deep purple pigment at the cell end walls (towards the leaf apex). Blade abaxial surface glabrous or hairy, hairs pilose (if applicable), hairs sparse or moderately dense, hairs white (with dark purple end walls), hairs straight or curved, hairs spreading. Blade margins entire, with non-glandular hairs (hairs forming a fringe); apices obtuse.

Reproductive morphology. Flowering stems with leaves. Flowering stems hairy. Flowering stems tomentose. Flowering stem hairs simple (multicellular); transparent with deep purple cross-walls. Inflorescences solitary heads; terminal. Flowering heads 10–15 mm deep; 10–20 mm wide; with disc and ray florets. Involucral bracts present. Number of rows 1–2. Outer involucral bracts mostly wine red or purple pigmented (usually dark purple); lying adjacent to the flowers; lanceolate; 5.5–8 mm high; 0.6–2 mm wide; densely hairy; without glandular hairs (but multicellular with 5–8 cells that have dark purple pigment at the cell cross-walls). Inner involucral bracts lanceolate (narrowly tapering to an acuminate tip); 7.5–8.5 mm high; 0.8–1 mm wide; margins narrow and scarious, less than one quarter of the bract; apex entire. 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; whitish. Ray florets pappus 4.5–5.5 mm long. Disc florets pappus 3.5–4.5 mm long. Petals conventional; fused; 5; white (disc florets with petal tips drying brown), or purple (ray florets, a deep blue purple, often drying pale whitish yellow); 3–4 mm long (disc florets). Corolla tubular, or funnel-form (disc florets), or flat, strap-like (ray florets); 2-lobed (ray florets), or 5-lobed (disc florets); helmet without 2 small teeth at the apex. Ray florets 50–80; limb 5–6 mm long; limb 0.4–0.6 mm wide. Stamens absent (1–1.2 appearing empty). Ovary inferior; carpels 2; syncarpous. Styles 1; 3.5–4 mm long. Stigmas per ovary 2. Placentation basal. Ovules per ovary 1. Fruit sessile (previous season's head that has shed fruit found, but no specimens with ripe fruits in Arctic Island specimens at CAN); with calyx persisting; dry; cypselas; hairy; indehiscent. Seeds 1.

Chromosome information. 2n = 36.

2n (4x) = 36. Holmgren (1919, northern Europe); Flovik (1940, Svalbard); Löve (1950, Iceland); Löve and Löve (1956, Iceland; 1982a, Arctic Canada); Jørgensen et al. (1958, Greenland); Packer (1964, Yukon); Zhukova (1965a, eastern Chukotka; 1967, northeastern Asia; 1980, southern Chukotka; 1982, northeastern Asia); Hedberg (1967, northern Canada); Engelskjøn (1967, northern Norway, three sites); Knaben and Engelskjøn (1967, northern Norway); Johnson and Packer (1968, northwestern Alaska); Taylor and Mulligan (1968, western Canada); Chinnappa and Chmielewski (1987, western North America); Dalgaard (1989, western Greenland). A few additional southern counts.

Ploidy levels recorded 4x.

Ecology and habitat. Substrates: around the margins of ponds, slopes, along streams (among boulders in stream beds); imperfectly drained moist areas, dry, moderately well-drained areas; gravel, moss; with high organic content, peat; calcareous (most often found in calcareous sites (Elven, personal communication, 2005)), or non-calcareous (granite), or nitrophilous (sheltered owl perch, CAN 261955). In mossy, grassy places, often growing in herbmats below persisting snow banks (Porsild 1957). Herbarium label notes indicate that plants grow in fens and heaths, dry gravelly south-facing slopes, and boulder ridges in stream beds.

North American distribution. Alaska, Yukon, Northwest Territories Islands, continental Northwest Territories, Nunavut Islands, continental Nunavut, northern Quebec, Labrador. Range in the Canadian Arctic Archipelago widespread. Uncommon. Low Arctic and alpine. Arctic islands: Baffin, Ellesmere, Banks, Victoria, Southampton, Coats (Digges Island, Melville and Simpson peninsulas).

Northern hemisphere distribution. Amphi-Atlantic, or amphi-Beringian, or North American. Northern Iceland, Northern Fennoscandian, Svalbard – Franz Joseph Land, West Chukotka, South Chukotka, East Chukotka, West Alaska, North Alaska – Yukon, Central Canada, Labrador – Hudson Bay, West Greenland, East Greenland.

General notes. Porsild (1957), in the key he provided, separated this species from E. uniflorus subsp. eriocephalus on a difference in the diameter of the flowering heads: the latter species being about 2 cm and E. humilis about 1 cm in diameter. However, there are many specimens 1–2 cm in diameter. In general, the flowering heads of E. humilis are smaller and narrower. In the field the difference is pronounced, and it is obvious that the capitula of E. humilis have a cuneate base, while those of E. uniflorus subsp. eriocephalus have a broadly rounded to truncate base (Elven, personal communication, 2005).

The hairs on the involucre of E. humilis are conspicuously different, appearing blackish purple from dark purple pigment at the cross-walls of the multicellular hairs. The ray florets of E. uniflorus subsp. eriocephalus are a pink purple, and the disc florets have the same colour on the tips of the petals. Both may have turned a whitish yellow in herbarium specimens. The ray florets of E. humilis are a bluish purple, and the disc florets may have petal tips that have dried either pale yellow or brown. The two taxa are easily distinguished (see pictures in image library) and probably not very closely related phylogenetically.

Interactions between ploidy level, breeding systems, and morphologic variation have been studied in detail in E. compositus. Five informally designated population systems of diploids are geographically restricted (all to the northwestern United States and closely adjacent Canada) and primarily sexual, compared to the polyploids, which are agamospermous and apparently of hybrid origin, at least in some cases (R.D. Noyes et al. 1995, Noyes and D.E. Soltis 1996). Reduction in ray floret laminae usually is correlated with polyploidy. Plants with once-ternately lobed leaves have been identified as E. compositus var. glabratus, an element of variation that does not have a geographic pattern.

Among its close relatives, Erigeron compositus is the only species that produces strongly thickened caudex branches; occasional collections show a tendency toward the slender, loose branches characteristic of the other species (personal communication, G. Nesom, author of the Flora of North America treatment, Jan. 2005).

Illustrations. • Habitat: Ogac Lake. Note two small white daisy-like flowers near the markers. Plants growing above waterline in wave-washed gravel with very little nutrient. Nunavut, Baffin Island, Ogac Lake. 12 July, 2004. Aiken and LeBlanc 04–071. CAN 586539. • Side view of flowering head. Plants in a nutrient rich habitat growing near those in the previous image but approximately four times the size. Side view of flowering head with deep purple involucral bracts covered with long purple and white hairs. 12 July, 2004. Aiken and LeBlanc 04–071. CAN 586539. • Plant habit. Plants growing in a sheltered gully with simple slightly hairy leaves, vivid purple and densely hairy involucrals bracts, white ray petals and yellow disc florets that are greenish before opening. N.W.T., Banks Island, Sachs Harbour. 27 July, 1981. J.M. Gillett 18856. CAN. • Close-up of plant. Flowering plant in shale scree. Norway, Svalbard, Kapp Thordsen. July, 1997. Photograph by R. Elven. • Close-up of plant. Plant in early flowering stage with pink marginal flowers and very dark-haired involucral bracts (phyllaries). Norway, Svalbard, Sassen. July, 1997. Photograph by R. Elven. • Plants in seed. White fluffy heads of plants setting seed. Nunavut, Baffin Island, Apex Hill. 19 August, 2006. Aiken. No voucher. • Contrasting capitula. Left, Erigeron uniflorus subsp. eriocephalus with reflexed phallaries. Right, Erigeron humilis with erect or slightly spreading phallaries. Drawing by Mrs. S. Bergh and Mrs. L. Barstad based on a collection from Svalbard, Andrée Land, E. uniflorus subsp. from ytterste fjeld på nordsiden av Purple Valley, sydvendt hylle, ca 450 msm. [outermost mountain on N side of Purple Valley, south facing ledge]. 14 August, 1928. O.A. Høeg. 0 200197. and E. humilis from Purpurdalen, ytterste fjell på sørsiden, sørvendt hylle, 450 msm. 14 August, 1928. O.A. Høeg. O 200921. With permission of the Botanical Museum University, of Oslo, Norway. • 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.