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

Taraxacum ceratophorum (Ledeb.) DC.

English: Horned dandelion,

French: Pissenlit corniculé,

Inuktitut: imugaq, misartaq (Nunavik).

Asteraceae (Compositae), Daisy family.

Published in Prodr. 7: 146. 1838.

Synonymy. Leontodon ceratophorus Ledebour, Ic. Pl. Fl. Ross 1: 9, pl.34. 1828.

Taraxacum eriophorum Rydberg, Mem. New York Bot. Gard. 1: 454. 1900.

Taraxacum dumetorum E.L. Greene, Pittonia 4: 230. 1901.

Taraxacum groenlandicum G.A.H. Dalstedt, Ark. Bot. 5, no. 9: 23, pl. 14, 15. 1906.

Taraxacum hyperboreum G.A.H. Dalstedt, apud Ostenfeld, Vid. -Selsk. Skr. Math.-Nat., Christiania, No. 8, 26. 1909.

Taraxacum ambigens var. fultius Fernald, Rhodora 35: 376, tab. 271, fig. 9. 1933

Taraxacum carthamopsis A.E. Porsild, Proc. and Trans. Roy. Soc. Canada 3rd. ser. sect. 5, 33: 32, tab. 1–3. 1939.

non Taraxacum lapponicum Porsild (1957).

Vegetative morphology. Plants (5–)10–30 cm high; perennial herbs; with milky juice. Taproot present. Robust. Caudex present (5–10 mm in diameter). Aerial stems a small transition zone between taproot and basal leaves. Leaves mainly basal; patent, or erect; alternate; dying annually and non-persistent. Petioles present, or absent (when attenuate leaf blades taper to where they are attached to the stem); 0–40(–70) mm long; winged (broadly or narrowly); glabrous. Leaf blades simple. Leaf blade bases attenuate. Blades 50–120 mm long, 7–30 mm wide, oblanceolate, flat, appearing single-veined or veins pinnate. Blade adaxial surface glabrous. Blade abaxial surface glabrous. Blades lobed (broadly or narrowly). Blade margins runcinate and dentate (leaves varying from sub-entire to leaves with deep, widely spaced, runcinate lobing), glabrous, with 1–8(–11) teeth on each side of the blade (counting dentations and tips of runcinate lobes), with teeth toward the apex; degree of incision 5–95%; apices acute.

Reproductive morphology. Flowering stems without leaves. Flowering stems hairy. Flowering stems woolly. Flowering stem hairs simple (and floccose near the inflorescence); longer than the diameter of the flowering stem; white or translucent. Flowers in inflorescences. Inflorescences solitary heads. Flowering heads 15–30 mm deep (side view); (25–)30–40 mm wide; with only ligulate florets. Pedicels absent. Involucral bracts present. Number of rows 2–3. Outer involucral bracts mostly green (dark green); lying adjacent to the flowers; ovate, or lanceolate (tapering towards a narrow apex); (5.5–)7–11 mm high; 1–3.5 mm wide (conspicuously longer than wide and proportionately narrow); glabrous. Inner involucral bracts lanceolate; 12–20 mm high; 2.5–3 mm wide; margins narrow and scarious, less than one quarter of the bract; apex prominently horned (or callosed). Flowers per inflorescence 40–60; bilaterally symmetrical (zygomorphic). Sepals represented by a pappus. Pappus with a single row of hairs; whitish. Ligulate florets pappus (5–)6–8 mm long. Petals conventional; fused; 5; yellow (pressing cream, almost white with a greyish stripe in the outer petals); without contrasting markings (when fresh), or with contrasting markings (sometimes drying with greyish tinges). Corolla flat, strap-like. Ray florets limb 1.5–2.5 mm wide. Ligulate florets limb 40–60 mm long; 10–14 mm wide. Stamens 5. Anthers yellow; 2.8–4.2 mm long. Ovary inferior; carpels 2; syncarpous. Styles 1; 7–8 mm long (conspicuously shorter than the petals). Stigmas per ovary 2. Placentation basal. Ovules per ovary 1. Fruit sessile; with calyx persisting; dry; cypselas; obovate; brown (a pale reddish brown), or red (brick coloured); (2.5–)4–5 mm long; 0.9–1.2 mm wide; glabrous; surface venation ribbed; indehiscent. Cypselas beak slender, often much longer than the body; surface spinulose; surface in upper half. Seeds 1.

Chromosome information. 2n = 16, or 18, or 28, or 32, or 40.

Numerous counts in the Index of Plant Chromosome Numbers (IPCN).

Ecology and habitat. Substrates: wet meadows (at the edges), along streams, lakeshores, ridges; imperfectly drained moist areas, seepage slopes; gravel, sand, clay; with low organic content, with high organic content; calcareous. Wet ground watered from a calcareous fen (CAN 259074); edge of wet meadow near ponds; near the base of granitic boulders (CAN 518231); among igneous rock outcrops; rare on dry earthen ledges of protected rock crevices on westfacing granite cliff; on washed moraine.

North American distribution. Alaska, Yukon, Northwest Territories Islands, continental Northwest Territories, Nunavut Islands, continental Nunavut, northern Quebec, Labrador. Range in the Canadian Arctic Archipelago limited. Uncommon. Low Arctic. Arctic islands: Baffin, Ellesmere, Axel Heiberg, Parry islands, Banks, Victoria, King William, Southampton.

Northern hemisphere distribution. North American. North Alaska – Yukon, Central Canada, Labrador – Hudson Bay, Ellesmere Land – Peary Land.

General notes. Hultén's (1968b) map shows Taraxacum ceratophorum (Ledeb.) DC. in the Canadian Arctic Archipelago. He said this species has leaves of various forms; all or at least some involucral bracts with a horn or tubercle below the apex; outer bracts mostly appressed and broader than the inner ones. Hultén (1968b) commented that T. ceratophorum is composed of a large group of small taxa, which maintain themselves as distinct units through seeds that are formed without fertilisation.

The name T. lacerum used in Porsild (1957) for some Baffin Island dandelions is considered inapplicable, as none of the specimens from the Canadian Arctic Archipelago resemble that species when compared with an isotype of that species that is from northern British Columbia. CAN! (see image library). After examining specimens that Porsild labelled T. lapponicum, Aiken and Brouillet (July 2003) found no reason for not merging them into their concept of T. ceratophorum.

Illustrations. • Dandelions at Apex in flower. View of the Hudson Bay Post, Nunavut, Baffin Island, Apex, with dandelions in direct line with the post. 13 July, 2002. Aiken. • Dandelions at Apex going to seed. Foreground dandelions going to seed. Nunavut, Baffin Island, Apex, behind the Hudson Bay Post. Photograph by L. Gillespie. • Habitat. Dandelions on the beach at Apex. Foreground plant to the left had vivid yellow flowering heads 2–3 cm in diameter (02–068), those in the background had orange-yellow flowering heads 1–2 cm in diameter (02–069). Aiken. Vouchers at MTJB. • Close-up of flowering head. Flowering head composed of ligulate florets. Note five lobes on the ends of each ligulate petal and curling forked stigmas. Nunavut, Baffin Island, Apex. 24 July, 2005. Photograph by Kathy Thornhill. • Fly visitor. Close-up of ligulate florets with five lobes on the ends of each ligulate petal and curling forked stigmas. Nunavut, Baffin Island, Apex. 24 July, 2005. Photograph by Kathy Thornhill. • Close-up of plant in bud. Plant with deeply runcinate older leaves and sub-entire young leaves. Nunavut, Baffin Island, Ogac Lake. Aiken and LeBlanc 04–076. CAN 586546. • Close-up of bud. Flowering head in bud with outer involucral bracts beginning to spread. This was the only species of dandelion seen along the edge of the lake. Nunavut, Baffin Island, Kimmarut, Soper Lake. Aiken 02–070. CAN. • Plants in Kimmirut. Plants growing in disturbed ground at the base of a power pole. Nunavut, Kimmirut, edge of hamlet. Aiken and Iles 02–070. CAN. • Plant with almost entire leaves. Plant with almost entire leaves. Nunavut, Baffin Island, Kimmirut. Aiken and Iles 02–070. CAN. • Underside of flowering head. Underside of flowering head showing conspicuous stripes in the outer ligulate petals and narrow membranous margins on the involucral bracts that have somewhat horn-like appendices. Aiken 02–070. CAN. • Side view of larger flowering head. Flowering stem with web-like hairs below the head that is vivid yellow and 2–3 cm in diameter. Involucral bracts have prominent horns, and yellow ligulate petals have narrow greyish stripes in them. Aiken 02–068. CAN. • Close-up of plant. Close-up of plant with deeply runcinate leaves, vivid yellow flowering heads that are 2–3 cm across. Aiken 02–068. CAN. • Habitat. Plants found among igneous south facing rock outcrops. Note the outer involucral bracts on the bud are spreading to reflex. The leaves are erect, a characteristic of southern dandelions. Nunavut, Baffin Island. 23 July, 1982. J.M. Gillett 19005. CAN. • Close-up of cypselas. Flowering head opened to show developing cypselas that are black and have prominent spines towards the apex (02–069). Plants of this collection number were beginning to set seed; those of 02–068 were not on 13 July, 2002. CAN. • Type of T. hyperboreum. Isotype of Taraxacum hyperboreum Dahlst. Plant collected Nunavut, King William Island, Gjoa Harbour. 5 August, 1905. G. Hansen 80.606. CAN 243014. • Type of T. russeolum. Isotype of Taraxacum russeolum Dahlst. Note horns visible on the inner phyllaries. Plant collected in Nunavut, Baffin Island, Kimmirut. 25–26 August, 1927. M.O. Malte 119207. CAN 111689. • Isotype of T. malteanum. Isotype of Taraxacum malteanum Dahlst. Specimen annotated as Taraxacum lacerum by Porsild. Nunavut, Baffin Island, Kimmirut. 2 August, 1928. M.O. Malte 120293. CAN 111630. This specimen is similar to others from southern Baffin Island and unlike the type T. lacerum from British Columbia. • 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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