Juncus trifidus L.
Juncaceae, rush family.
Sp. Pl. 1: 326. 1753.
Described from Scotland.
Vegetative morphology. Plants perennial herbs; 10–20(–30) cm high; caespitose; forming dense tufts from a matted creeping horizontal stem. Ground-level or under-ground stems horizontal; rhizomatous (rhizomes with numerous yellowish-brown and somewhat lustrous, fibrous sheaths 1–3 cm long); compact. Aerial stems erect (stiff and wiry); circular or oval in cross-section; glabrous. Leaves in a basal tuft (occasionally cauline); alternate; simple; existing for a single season or less (blades), or marcescent (sheaths). Petioles absent. Sheaths with the margins fused to the apex. Ligules absent. Blades 20–75(–100) mm long; 0.4–0.8 mm wide (filiform). Blades straight; linear; with blade auricles (lacerate, 2–3 mm long); flat, or caniculate (fleshy); veins parallel. Blades adaxial surface glabrous. Blades abaxial surface glabrous. Leaf apices acuminate.
Reproductive morphology. Flowering stems present. Flowering stems with leaves; glabrous. Leaf or reduced bract closely associated with the base of the inflorescence present; conspicuous and leaf-like (usually 2 or 3 leaves that extend well beyond the inflorescence). Flowers solitary (rarely), or in inflorescences (usually). Inflorescence cymose, or head-like; dense; 0.2–0.6 cm long. Pedicels present, or absent (but very short). Flowers per inflorescence 1–5; small, less than 5 mm in diameter or length. Floral bracts apex entire. Calyx sepals 3; free; 2–5 mm long. Calyx brown; scarious; glabrous. Petals free; same length as the calyx (or slightly shorter); 3; brown (and scarious); lanceolate; unlobed; 2–5 mm long. Stamens 6. Anthers 1–1.2(–1.5) mm long. Gynoecia superior. Carpels syncarpous; 3. Styles 1. Stigmas per style 3. Ovules 15–25. Fruit sessile. Fruit with calyx persisting; dry; a capsule; elongate-cylindrical (with a pointed top); not distinctly flattened; dehiscent. Fruit 2.5–3.5 mm long; 1–1.5 mm wide; brown. Seeds 15–25; 1–1.4 mm long (irregular and variable in form with attenuate membranous structures at both ends); brown (yellowish); with surfaces smooth.
Chromosome information. 2n = 30 (&40). 30. -
Löve and Löve (1944a northern Europe,1956b Iceland, 1966b); Skalinska
et al. (1957 central Europe); Kørgensen et al. (1958 Greenland);
Engelskjøn and Knaben (1971 Norway); Nilsson and Snogreup (1972a northern
Europe); Micieta (1980 central Europe); Gervais (1981 eastern Canada); Druskovic
(1995 southern Europe).
40. - Moore and Clemants (2000, secondary
reference).
Distribution. Northern hemisphere distribution: amphi-Atlantic; Greenland, Canada. Low arctic. Range in the Canadian Arctic Archipelago limited. Uncommon. Arctic Islands: Baffin.
Ecology and habitat. Substrates: slopes; on seepage slopes, or dry; gravel, sand. Habitats: 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.
Notes. Polunin (1940) considered this species a "southern" type,
apparently eking out a rather precarious existence and sometimes only 5 or 6 cm
high, although more often attaining a height of some 15 cm. Marchand and Roach
(1980), in a study of reproductive strategies of pioneering alpine species,
reported that in the White Mountains of New Hamsphire J. trifidus
appeared capable of sexual reproduction. Successful invasion of disturbed sites,
however, was probably restricted to fairly local areas where there is a high
fallout of seed.
Bayfield (1996) in a study of long-term changes in
colonization of bulldozed ski slopes found that, generally where grass seeding
was done, most local vascular species were more effective colonizts of seeded
than of untreated ground but an exception was J. trifidus, which was more
successful on unsown ground.
Roach and Marchand (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 vigor
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.
Roach and Marchand (1984), in a study of revegetation of an alpine area
disturbed by excessive human activity along the Appalachian Trail (USA), using
the native species Arenaria groenlandica, J. trifidus, and
Potentilla tridentata recorded recruitment and mortality in
populations of sown seed. Environmental parameters were measured to assess their
impact on the population dynamics. The results showed similar patterns of
establishment on hiker disturbed sites and on naturally open, undisturbed sites.
Frost activity in the soil was the only identifiable cause of mortality. A
fertilization treatment had no effect on establishment or survival. The species
that had relatively rapid root growth had the highest rates of survival.
Illustrations. • Plant habitat. Brown plants growing among the green grass at a revegetating site near the abandoned mine head at Roros, Norway. Aiken s.n. • Close-up of plants. Plants with brown globose inforescences in the axiles of two long bract leaves. Roros, Norway. Aiken s.n. • Close-up of inflorecence. Fruiting inflorescences in the axils of two long bracts. Sepals and petals are brown, fuiting capsules are almost black. Roros, Norway. Aiken s.n. • Herbarium sheet. Plant with long leaves associated with the inflorescence. Collected by Père Arthème Dutilly, Aug 27, 1936 from Nunavut, Baffin Island, Kimmirut. CAN 10119. • Close-up of inflorescence. Right: Plant in flower with conspicuous stigmas (st) and auricles at the base of the leaf (au). Note the bracteoles (br) subtending the flowers. Above: Mature capsule with pointed top (pt). • Arctic Island distribution.
Cite this publication as: ‘S.G. Aiken, M.J. Dallwitz, L.L. Consaul, C.L. McJannet, L.J. Gillespie, R.L. Boles, G.W. Argus, J.M. Gillett, P.J. Scott, R. Elven, M.C. LeBlanc, A.K. Brysting and H. Solstad. 1999 onwards. Flora of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval. Version: 29th April 2003. http://www.mun.ca/biology/delta/arcticf/’. Dallwitz (1980) and Dallwitz, Paine and Zurcher (1993, 1995, 2000) should also be cited (see References).
