040107 Equisetummackaii (Newman) Brichan
Northern Iceland: Rare
Western Greenland: Present (Frequency unknown)
Southern Arcti Tundra: Presence uncertain
Shrub Tundra: Rare
Bordering boreal or alpine areas: Frequent
- Brichan, Phytologist 1: 369 (1843). - Equisetum hyemale var. mackaii Newman, Phytologist 1: 305 (1843 Sept. 1842). Type (K?): Northern Ireland: Belfast, Colin Glen, Aug. 1833, leg. Mackay and Whitla.
- Equisetum hyemale subsp. trachyodon A. Braun, Flora 22: 305 (1839). Type (B): Germany, "Ad Rhenum prope Carlsruhe", Aug. 1837, leg. Braun. - Equisetum x trachyodon (A. Braun) W.D.J. Koch, Syn. Fl. Germ. Helv., ed. 2, 3: 967 (1845).
- Equisetum hyemale (subsp. hyemale) x variegatum (subsp. variegatum).
Geography: North American (E) - amphi-Atlantic - European: ICE GRL.
Notes: See Hauke (1993) and Kartesz and Gandhi (1991) for why Braun's name Equisetum trachyodon from 1839 should be considered a subspecific name and why Brichan's combination of E. mackaii from 1843 therefore have priority.
Elven and Solstad: Equisetum x mackaii is recorded from Greenland and the arctic parts of Iceland (there as rather frequent). In addition, it is fairly frequent in Scandinavia but not yet recorded from the arctic parts.
Another question is whether E. x mackaii occurs independent of its parents. If the report from southern Greenland (Böcher et al. 1978: "Quagssiarsuk, Igaliko Fj.") is correct, it certainly does. Equisetum hyemale is only known from a rather distant locality in southeastern Greenland (Daniëls and van Herk 1984). See also Hauke (1993) who mapped a significant range for E. x mackaii in southern and western Greenland, northwards almost to Disko Island, everywhere in the absence of E. hyemale (and without any comment on this strange range). If E. x mackaii is a spore-sterile hybrid without means of long distance vegetative dispersal, this range in Greenland is inxeplicable. In Scandinavia, and especially in Iceland, E. x mackaii occurs fairly independent of its parents. In Scandinavia this may be explained by vegetative dispersal along several large waterways. The situation is different in Iceland where it is frequent (AMNH, ICEL) and regularly found in the absence of at least one of its parents. Spores are reported to abort but the matter should be re-investigated in light of its independence from its proposed parents in Iceland and Greenland.
Equisetum x mackaii has been reported from non-arctic parts of northeastern North America (Hauke 1993), there most probably with E. hyemale subsp. affine as one parent.
- Equisetum [0401,genus]