Stuckenia filiformis (Persoon) Börner subsp. alpina (Blytt) R.R. Haynes, Les, & M. Král
Potamogetonaceae, pondweed family.
Potamogeton filiformis Pers. var. alpinus (Blytt) Aschers & Graebn.
Potamogeton filiformis var. borealis (Raf.) St. John. (Hultén 1968).
Potamogeton filiformis var. macounii Morong. Hultén (1968) indicated that var. borealis has a shorter, more compact spike of greater length than the leaves, low growth, and seems to be merely a growth form and apparently an adaptation to Northern conditions.
Plants perennial herbs (totally submerged); aquatic, grass-like when the plants are not in flower; (5–)10–30 cm high (or more in deep, clear, "warm" water); vegetatively proliferating by bulbils not in the inflorescence (propagules are white tubers borne at the ends of rhizomes). Taproot present. Ground-level or under-ground stems horizontal; stoloniferous, or rhizomatous (if horizontal stems become buried in soft mud); elongate, or compact. Aerial stems erect (flaccid, jointed and leafy); glabrous. Leaves distributed along the stems; alternate (all submerged); simple; deciduous. Stipules present (united at their base, separate at the attenuate tips; variable in form). Petioles absent. Blades 25–100(–120) mm long; 0.2–0.7 mm wide (filiform); membranous; linear; with parallel veins; glabrous. Leaf apices acute.
Flowering stems 2–6(–12) cm long; without leaves; glabrous. Inflorescences spicate (with 2–4 whorls of flowers). Flowers per inflorescence 6–14; small, less than 5 mm in diameter or length; actinomorphic. Calyx sepals 4; free (one single whorl of sepal-like tepals that are fleshy-firm, valvate and shortly clawed); green; fleshy; glabrous. Petals absent. Stamens 4. Carpels apocarpous; 4 (alternating with the stamens). Gynoecia superior. Styles absent. Ovules 1. Fruit with calyx persisting; an achene; spherical (somewhat flattened); indehiscent; 1.8–2 mm long; 1.6–1.8 mm wide; dry; black, or brown (where seed shows through the thin green fruit wall); glabrous. Seeds 1 (per carpel, the seed attached to the ventral margin of the carpel towards the base); 0.3–0.4 mm long; brown; smooth (or with a slight ridge and a few tubercles).
Chromosome information. 2n = 78, 5 counts, Löve and Löve (1975) for P. filiformis.
Distribution. Circumpolar. Low arctic. Range in the Canadian Arctic Archipelago limited. Uncommon. Arctic Islands: Baffin (recorded from Iqaluit), Southampton (Coral Harbour).
Ecology and habitat. Substrates, aquatic; silt. Mud in shallow lakes and pools; only the inflorescence emergent.
Notes. 'A good duck food' (Fassett 1940).
The stipules of Stuckenia are adnate to the blade for two-thirds to nearly the entire length of the stipule. The few species of Potamogeton with adnate stipules have the adnation less than half the length of the stipule, or less than 4 mm. Submerged leaves of Potamogeton are translucent, flat and without grooves or channels, whereas those of Stuckenia are opaque, channeled and turgid (Haynes and Haynes, 1996).
Three distinct subspecies apparently occur in North America. They are separated mainly by the size of the plants and peduncle characteristics.
A proposal to elevate Potamogeton subg. Colegeton, was presented by Haynes and Haynes (1996). Potamogeton pectinatus was chosen as the nomenclatural type. The name Stuckenia had been previously published, however, and P. pectinatus cited (C. Böner 1912), making the generic name Coleogeton superfluous. Stuckenia is the correct name and the appropriate specific combinations have been made (Holub 1997). (Haynes, D.H. and R.R. Haynes,1996).
The Flora of North America treatment stated that no specimens had seen seen from Nunavut, but the subspecies is to be expected there (Haynes, D.H. and R.R. Haynes, 1996). Vouchers specimens for the three Nunavut records on the map in the image library, are housed at CAN.
Illustrations. • Herbarium specimen. Plant less than 15 cm tall with small inflorescence and flowers or fruit close together. Nunavut, Baffin Island, Iqaluit, 1 km west of the airport terminal in a shallow pool, growing with Hippus. D.F. Brunton, and K.L. McIntosh 9901. CAN 549906. • Close-up of stipule. Midstem stipule with summit, indicated by the upper arrow, close to the stem and about the same width as the stem. Lower arrow, stipular sheath inflated on proximal portion of the stem. Nunavut, Baffin Island, Iqaluit, 1 km west of the airport terminal in a shallow pool, growing with Hippus. D.F. Brunton, and K.L. McIntosh 9901. CAN 549906. • 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).
