Juncus arcticus Willd. s.l.
Juncaceae, rush family.
Sp. Pl. ed. 4: 206. 1799.
Juncus arcticus subsp. alaskanus Hultén
Plants not caespitose; with stems growing in more or less straight rows from a horizontal ground-level stem; less than 15 cm high, or more than 15 cm high (usually); (10–)15–40(–50) cm high. Ground-level or under-ground stems horizontal (robust); rhizomatous, or stoloniferous; elongate, or compact. Aerial stems erect (irregularly striate, non-flowering stems few or absent); circular or oval in cross-section; glabrous. Leaves absent, or reduced and scale-like near the base of the stem.
Flowering stems without leaves; glabrous. Leaf or reduced bract closely associated with the base of the inflorescence present; conspicuous and leaf-like (1.5–5 cm long, erect and stiff). Inflorescences head-like; inflorescence terminal (appearing axillary at the base of the bract); inflorescence dense; inflorescence 0.6–1 cm long. Flowers per inflorescence 2–5(–8); small, less than 5 mm in diameter or length (or just over 5 mm; more or less sessile); sessile or subsessile. Floral bracts apex entire. Calyx sepals 3; free; brown; scarious; glabrous. Petals 3; free; brown (scarious); lanceolate; unlobed; 3–5 mm long; shorter than the calyx, or same length as the calyx. Stamens 6. Anthers 0.7–1 mm long (shorter or as long as their slender filaments). Carpels syncarpous; 3. Gynoecia superior. Styles completely fused. Styles 1. Stigmas per style 3. Ovules 30–100. Fruit with calyx persisting; a capsule; ovoid, or elongate-cylindrical, or obovate; not distinctly flattened (but concave and slightly notched at the apex); dehiscent; 3.5–4.5 mm long; 1.8–2.2 mm wide; sessile; dry; black, or brown. Seeds 30–100; 0.4–1 mm long; brown; smooth.
Chromosome information. 2n = 80, 84.
Distribution. Circumpolar. Arctic. Range in the Canadian Arctic Archipelago limited. Common (where it occurs). Arctic Islands: Baffin, Ellesmere, Banks, Victoria, Southampton (records rom Ellesmere Island were not known to Porsild (1957)).
Ecology and habitat. Substrates, around the margins of ponds, marshes, along streams (on sand bars), seashore (in deltas, or in marshes just above the high tide line, frequently associating with obligate halophyptes); imperfectly drained moist areas; calcareous; sand, clay (alluvial); with low organic content, or with high organic content. A pioneer species.
Notes. Porsild and Cody (1980) report J. balticus subsp. alaskanus Hultén (synonomous with J. arcticus subsp. alaskanus Hultén) on adjacent continental North America, and also on Victoria and Banks Islands. We could not separate the CAN specimens collected in the Canadian Arctic Islands on the anther, inflorescence or capsule characters usually used to recognise separate subspecies.
Illustrations. • Herbarium specimen. Herbarium specimen showing horizontal stems with vertical stems (s) arising in the same plane. At the base of the plant are conspicuous 'prophylls', (p) the sheath-only portion of a leaf. The true leaves (lv) subtend the inflorescences and appear to extensions of the stem. CAN 204835. • Close-up of inflorescence. Plants showing an apparently lateral inflorescence at the base of a leaf (terete bract) that looks like a continuation of the stem. Note, the tops of capsules are blunt or slightly concave. CAN 507382. • Arctic Island distribution.
Cite this publication as: ‘S.G. Aiken, M.J. Dallwitz, L.L.Consaul, R.L. Boles, R. Elven and M.E. LeBlanc. 2001 onwards. Flora of the Canadian Arctic Archipelago. Volume 1. Pteridophytes and Monocotyledons: Descriptions, Illustrations, Identification, and Information Retrieval. Version: 16th March 2001. http://www.mun.ca/biology/delta/arcticf/’. Dallwitz (1980), Dallwitz, Paine and Zurcher (1993, 1995, 2000), and Aiken, Dallwitz et al. (1999) should also be cited (see References).
