Flora of the Canadian Arctic Archipelago
English: Horned dandelion,
French: Pissenlit tuberculé, Pissenlit du grand nord.
Asteraceae (Compositae), Daisy family.
Published in Ark. Bot. 4, 8: 17. 1905.
Type: Nunavut: Baffin Island. Arctic Bay. Dutilly 1385.
Vegetative morphology. Plants (3–)5–15(–30) cm high (DAO specimen); perennial herbs; with milky juice. Taproot present. Caudex present. Aerial stems a small transition zone between taproot and basal leaves. Leaves basal in a rosette; patent; alternate; dying annually and non-persistent. Petioles absent (young leaves), or present (mature leaves); 0–70 mm long; winged, or not winged; glabrous. Leaf blades simple. Leaf blade bases attenuate. Blades 20–120 mm long, (3–)5–12 mm wide, oblanceolate (runcinate; but usually not as strongly as T. holmanenum, and never with additional dentations on the lobes), flat, appearing single-veined or veins pinnate (lateral veins small). Blade adaxial surface glabrous. Blade abaxial surface glabrous. Blades lobed or not lobed. Blade margins runcinate, glabrous, with teeth toward the apex; degree of incision 0–50%; apices acute.
Reproductive morphology. Plants bisexual, or agamospermic (specimens annotated as lacking pollen). Flowering stems without leaves. Inflorescences solitary heads. Flowering heads 15–30 mm deep; 30–40 mm wide (when fully expanded; this species is often pressed with the capitulum open); with only ligulate florets. Pedicels absent. Involucral bracts present. Number of rows 2–3. Outer involucral bracts mostly green (to bluish black and sometimes purplish red); spreading to erect; ovate; 6–8 mm high; 3.5–4.5 mm wide (conspicuously wide at the base); glabrous. Inner involucral bracts lanceolate; 11–14 mm high; 1.5–3.5 mm wide (variable in width); margins wide, scarious for at least one quarter of the bract; apex sometimes callused, but without a prominent horn (tips somewhat callose, or rarely with small coniculate appendages). Flowers per inflorescence 30–50; bilaterally symmetrical (zygomorphic). Sepals represented by a pappus. Pappus with a single row of hairs; whitish. Ligulate florets pappus 6–7 mm long. Petals conventional; fused; 5; white, or yellow (cream), or pink (as a tinge towards the ends of the petals); with contrasting markings (stripes of pinkish colour in outer ligules; often drying on herbarium specimens with a pink and grey stripe). Corolla flat, strap-like. Ray florets limb 0.8–1.4(–2) mm wide. Ligulate florets limb 25–50 mm long; 9–18 mm wide. Stamens present, or absent (character needs additional study); 5. Anthers yellow; 3–3.5 mm long. Ovary inferior; carpels 2; syncarpous. Styles 1. Stigmas per ovary 2. Placentation basal. Ovules per ovary 1. Fruit sessile; with calyx persisting; dry; cypselas; obovate; yellowish, or straw-coloured (sometimes greyish, Porsild (1957) olivaceous); 3–4 mm long; 0.7–1 mm wide; glabrous; surface venation ribbed; indehiscent. Cypselas beak slender, often much longer than the body; surface spinulose; surface in upper half (strongly). Seeds 1.
Chromosome information. 2n = 24, 32, and 40.
The following chromosome counts are reported under this name, many of them probably erroneously:
2n (3x) = 24. Krogulevich (1976a, northern Siberia); Petrovsky and Zhukova (1981, Wrangel Island); Zhukova (1982, northeastern Asia);
2n (4x) = 32. Petrovsky and Zhukova (1981, Wrangel Island), Tzvelev and Zhukova (1986, north and northeastern Asia), Zhukova and Petrovsky (1987b, northeastern Asia);
2n (5x) = 40. Zhukova and Petrovsky (1980, western Chukotka), Petrovsky and Zhukova (1981, Wrangel Island).
Ploidy levels recorded 3x, 4x, and 5x.
Ecology and habitat. Substrates: dry, moderately well-drained areas. Raised sand terraces, low-centre polygons on old surfaces (CAN 526820); dry sunny slopes (CAN 128178); sandy, wind-eroded knolls; marine/lacustrine deposits (CAN 533240); rocky stream beds (CAN 483748); a high bird perch in a silt plain (was a very vigorous plant, CAN 267765).
North American distribution. Alaska, Yukon (?), Northwest Territories Islands, continental Northwest Territories, Nunavut Islands. Range in the Canadian Arctic Archipelago widespread. Common. High Arctic. Arctic islands: Baffin, Ellesmere, Axel Heiberg, Parry islands, Banks, Victoria.
Northern hemisphere distribution. Amphi-Beringian, or North American. Wrangel Island, East Chukotka, West Alaska, Central Canada, Labrador Hudson Bay, Ellesmere Land Peary Land, West Greenland (?).
General notes. The sub-entire or shallowly dentate leaves are similar to those of T. phymatocarpum. Taraxacum hyparcticum differs from T. phymatocarpum in having wide scarious margins on the inner involucral bracts, much larger and relatively large, pale creamy yellow heads with ligulate petals that often have a tinge of pink. The heads spread fully open and flat at anthesis; those of T. phymatocarpum spread less. The cypselas of T. hyparcticum have beaks that are often tinged rusty orange; the cypsela surfaces are straw-coloured with a reddish tinge or olivacous. They are often only spinulose towards the apex and similar to the illustration in Dahlstedt (1905, p. 21). The cypselas of T. phymatocarpum are grey or black with conspicuous longitudinal grooves and well-developed spicules over most of the surface.
Porsild (1957) reported pollen lacking. A specimen from Axel Heiberg Island (CAN 295570) is annotated as "some pollen present" on the label.
Illustrations. • Plant habit. Plant with creamy yellow flowers and leaves that are shallowly lobed, growing on a salt-flat near the sea. N.W.T., Banks Island, Sachs Harbour. 25 July, 1981. J.M. Gillett 18816. CAN. • Close-up of flower. Flower with pale creamy yellow petals that have a slightly pinkish tinge and greenish stigmas. N.W.T., Banks Island, Sachs Harbour. 25 July, 1981. J.M. Gillett 18816. CAN. • Black and white plate. Illustration from the type description by Dahlstedt (1905). Note the broadly ovate outer involucral bracts (7–10) and the scarious margins on the inner involucral bracts (11–12), the entire, sub-entire and slighly runcinate leaves and the fruit that is spinulose in the upper half. • 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..