Minuartia rossii
Minuartia dawsonensis
Ross' sandwort
minuartie de Dawson, rock stitchwort
stout, woody.
filiform to somewhat thickened.
ascending to spreading, green or often purple, 1–3 cm, glabrous, internodes of flowering stems 0.2–1 times as long as leaves.
erect to ascending, green, 4–30 cm, glabrous, internodes of flowering stems 1–10 times as long as leaves.
overlapping, ± tightly (vegetative), ± evenly spaced proximally (cauline), connate-perfoliate proximally, with tight, herbaceous sheath 0.2–0.3 mm;
blade upwardly curved, green or often purple, keeled, prominently 1-veined abaxially, subulate, 3-angled, 1–4 × 0.5–0.7 mm, flexuous, margins rounded, herbaceous, smooth, apex green to purple, rounded, navicular, shiny, glabrous;
axillary leaves well developed.
overlapping or crowded proximally, variably spaced distally, connate proximally, with tight, scarious to herbaceous sheath 0.2–0.5 mm;
blade straight to slightly outwardly curved, green, flat, 1-veined, occasionally 3-veined abaxially, linear to subulate, 4–15 × 0.5–2 mm, flexuous, margins not thickened, scarious, smooth, apex green or purple, mostly rounded, slightly navicular, shiny, glabrous;
axillary leaves present among proximal cauline leaves.
solitary flowers, axillary or terminal (rarely present);
bracts absent.
7–15-flowered (rarely fewer), open cymes;
bracts subulate, herbaceous.
0.1–2 cm, glabrous.
0.3–2.5 cm, glabrous.
hypanthium disc-shaped;
sepals 1-veined, oblong-ovate (herbaceous portion usually purple, oblong-ovate), 1.5–2.5 mm, not enlarging in fruit, apex often purple, obtuse to acuminate, navicular, not hooded, glabrous;
petals obovate to spatulate, 1.5–2 times as long as sepals, apex obtuse, entire.
hypanthium disc-shaped;
sepals prominently 3-veined, ovate to broadly lanceolate (herbaceous portion ovate to broadly lanceolate), 2.5–3.2 mm, to 4 mm in fruit, apex green to purple, acute to apiculate, not hooded, glabrous;
petals lancolate to spatulate, 0.5–0.8 times as long as sepals, apex rounded, entire, or petals absent.
on stipe ca. 0.1–0.2 mm, spheric, 1.5–2.5 mm, equaling sepals.
on stipe ca. 0.2 mm, ovoid, 3.5–4.5 mm, longer than sepals.
brown, suborbiculate, compression unknown, ca. 0.6 mm, obscurely reticulate.
dark brown to black, suborbiculate with radicle prolonged into tiny beak, 0.5–0.6 mm, tuberculate;
tubercles low, rounded, somewhat elongate.
= 58 (Russia), 60.
= 30, 60.
Minuartia rossii
Minuartia dawsonensis
Minuartia rossii is the northernmost member of the M. rossii complex (S. J. Wolf et al. 1979; B. Maguire 1958), a pulvinate species of moist arctic areas. While specimens occasionally have many flowers, some specimens have few if any, instead reproducing via small axillary fascicles of leaves or short shoots in the upper leaf axils (see also Ö. Nilsson 2001).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Although sometimes included in Minuartia michauxii [e.g., H. J. Scoggan’s (1978–1979, part 3) treatment of Arenaria stricta], M. dawsonensis is more closely related to the circumpolar M. stricta.
Minuartia litorea, known from Quebec and Ontario, may deserve recognition. An unpublished chromosome count suggests that it is a recent allopolyploid derived from M. dawsonensis and M. rubella (L. Brouillet, pers. comm.).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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