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

Juncus trifidus L.

English: Highland rush,

French: Jonc trifide,

Inuktitut: Iviit, ivisuka, ivitsuskaka.

Juncaceae, Rush family.

Published in Sp. Pl. 326. 1753.

Synonymy. "Habitat in Alpibus Lapponicis, Helveticis, Pyrenæis".

Vegetative morphology. Plants 10–20(–30) cm high (to 40 cm tall in continental North America); perennial herbs; caespitose. Only fibrous roots present. Ground level or underground stems horizontal; rhizomatous (rhizomes with numerous yellowish brown and somewhat lustrous, fibrous sheaths 1–3 cm long); compact. Aerial stems erect (stiff and wiry; sometimes drooping). Leaves mainly basal (occasionally cauline; cataphylls 2–4); alternate; dying annually and non-persistent (blades), or marcescent (sheaths). Petioles absent. Sheaths present; with the margins fused to the apex. Ligules absent. Leaves grass-like. Blades 20–75(–100) mm long, 0.4–0.8 mm wide (filiform). Leaves filiform. Blades straight, linear, with sheath auricles (lacerate, 2–4 mm long), flat or channelled (slightly), veins parallel. Blade adaxial surface glabrous. Blade abaxial surface glabrous. Blade margins entire or serrulate (finely), glabrous; apices acuminate.

Reproductive morphology. Flowering stems two or more per plant. Flowering stems circular or oval in cross section. Flowering stems with leaves. Leaf or reduced bract subtending the base of the inflorescence present; conspicuous and leaf-like (usually 2 or 3 leaves that extend beyond the inflorescence); exceeding the inflorescence (as two or three long thin leaves). Flowers in inflorescences (very rarely solitary). Flower orientation flowers side by side in a horizontal plane. Inflorescences cymose, or head-like; terminal; dense; ovate (at the base of long thin leaves); 0.2–0.6 cm long. Pedicels present, or absent (but very short). Bisexual spike(s) without empty bracts at the base. Floral bracts apices entire (bracteoles 2, usually lacerate). Flowers per inflorescence 1–4; small. Sepals conventional (brown tepals); 3; free; 2–5 mm wide; brown; scarious. Calyx glabrous. Petals conventional (brown tepals); free; same length as the calyx (or slightly shorter); 3; brown (and scarious); lanceolate; unlobed; 2–5 mm long (inner series slightly shorter; lanceolate). Stamens 6. Anthers 1–1.2(–1.5) mm long. Ovary superior; carpels 3; syncarpous. Styles 3; free; 0.5–0.6 mm long (stigmas to -2.0 mm on top of style). Stigmas per ovary 3. Ovules per ovary 15–25. Fruit sessile; with calyx persisting; dry; a capsule; ellipsoid, or elongate-cylindrical (longer than the tepals and with a pointed top); brown; (2.5–)2.7–3.5 mm long; 1–1.5 mm wide; not distinctly flattened; dehiscent. Seeds 15–25; 1–1.4 mm long (obliquely ovoid, with attenuate membranous structures at both ends); brown (yellowish); surfaces smooth.

Chromosome information. 2n = 30. Löve and Löve (1944a, northern Europe, 1956); Skalinska et al. (1957, central Europe); Jørgensen et al. (1958, Greenland); Engelskjøn and Knaben (1971, Norway); Nilsson and Snogerup (1972a, northern Europe); Micieta (1980, central Europe); Gervais (1981, eastern Canada); Druskovic (1995, southern Europe).

2n = 40. Brooks and Clemants (2000, secondary reference).

Ecology and habitat. Substrates: slopes; dry (In Europe, often a pioneer on new road verges, and in "slalom" slopes in ski areas, in northern mountains); gravel, sand. Occurs on springy or sandy slopes on Baffin Island. In the Beekman Peninsula, the plant is found in sheltered sandy sites, often in iron-rich sands.

North American distribution. Nunavut Islands, northern Quebec, Labrador. Range in the Canadian Arctic Archipelago limited. Uncommon. Low Arctic. Arctic islands: Baffin.

Northern hemisphere distribution. Amphi-Atlantic. Northern Iceland, Northern Fennoscandian, Kanin–Pechora, Polar Ural – Novaya Zemlya, Yamal–Gydan, Taimyr – Severnaya Zemlya, Labrador – Hudson Bay, West Greenland, East Greenland.

General notes. Polunin (1940) considered this species a "southern" type, apparently eking out a rather precarious existence in arctic and alpine regions and sometimes only 5 or 6 cm high, although more often attaining a height of some 15 cm.

Bayfield (1996), in a study of long-term changes in colonisation of bulldozed ski slopes, found that, generally where grass seeding was done, most local vascular species were more effective colonists of seeded than of untreated ground, but an exception was J. trifidus, which was more successful on unsown ground.

Marchand and Roach (1980), in a study of reproductive strategies of pioneering alpine species seed production, dispersal, and germination, found that J. trifidus showed high production of viable seed, high germination percentages, and relatively high (albeit short-range) seed mobility, combining the advantages of perennial longevity with reproductive vigour more typical of annuals. While J. trifidus appeared capable of sexual reproduction, successful invasion of disturbed sites was considered probably restricted to fairly local areas where there is a high fallout of seed.

Illustrations. • Habitat. Brown plants growing among the green grass at a revegetating site near the abandoned mine head at Roros, Norway. Aiken. No voucher. • Close-up of plants. Plants with brown globose inflorescences subtended by two long leaf-like bracts. Norway, Roros. Aiken s.n. • Herbarium sheet. Note buildup of marcescent sheaths at plant base. Nunavut, Baffin Island, Kimmirut. 27 August, 1936. Père Arthème Dutilly. Nunavut, Baffin Island, Kimmirut. CAN 10119. • Junction between culm and leaves. Culm apex with two long leaf-like bracts subtending inflorescence. The central flower is at anthesis. Nunavut, Baffin Island, Ogac Lake. 15 July, 2004. Aiken and LeBlanc 04–214. CAN 586596. • Close-up of inflorescence. Inflorescence of three flowers subtended by two long leaf-like bracts. The young capsule, seen here in the central flower, has a characteristically pointed apex. Nunavut, Baffin Island, Ogac Lake. 15 July, 2004. Aiken and LeBlanc 04–214. CAN 586596. • Plants in fruit. Fruiting inflorescences subtended by two long leaf-like bracts.The capsules are almost black and surrounded by persistent brown tepals. Norway, Roros. Aiken s.n. • 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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