Minuartia glabra
Minuartia obtusiloba
Appalachian sandplant, Appalachian stitchwort
alpine sandwort, alpine stitchwort, arctic sandwort, twin-flower sandwort
filiform.
stout, woody.
erect or ascending, green, 9–20 cm, glabrous, internodes of all stems 2–7 times as long as leaves.
erect, green, 1–12 cm, trailing stems 2–20+ cm, stipitate-glandular, internodes of flowering stems 1–6 times as long as leaves.
overlapping proximally (basal rosette absent at flowering), connate proximally, with ± loose, scarious sheath 0.2–0.5 mm;
blade ascending to spreading, green, 1-veined abaxially, flat, linear, 5–20(–30) × 0.5 mm, flexuous, margins not thickened, slightly scarious, smooth, apex green to purple, rounded to acute, dull, glabrous;
axillary leaves absent.
tightly overlapping (vegetative), variably spaced (cauline), usually connate proximally, with tight, scarious to herbaceous sheath 0.3–1.5 mm;
blade straight to outwardly curved, green, 3-angled, 3-veined abaxially, midrib prominent, lateral veins weak in distal 1/3, needlelike to subulate, 1–8 × 0.4–1 mm, flexuous, margins not thickened, herbaceous, sometimes finely ciliate, apex green, rounded to acute, often apiculate, somewhat navicular, shiny, glabrous;
axillary leaves present among vegetative leaves.
8–15-flowered, open, leafy cymes;
bracts linear to subulate, mostly herbaceous.
solitary flowers, terminal, or occasionally in 2–3-flowered, open cymes;
bracts subulate, herbaceous.
0.5–2 cm, glabrous.
0.3–1.5 cm, stipitate-glandular.
hypanthium disc-shaped;
sepals obscurely veined, oblong-lanceolate, lanceolate, to elliptic (herbaceous portion oblong-lanceolate or lanceolate to elliptic), 1.5–4 mm, to 4.5 mm in fruit, apex green, ± rounded, not hooded, glabrous;
petals clawed, broadly obovate, 1.5–2.2 times as long as sepals, apex rounded, shallowly notched.
hypanthium cup-shaped;
sepals prominently 3-veined proximally, narrowly ovate to oblong (herbaceous portion lanceolate to oblong), 2.9–6.5 mm, not enlarging in fruit, apex often purple, narrowly rounded, hooded;
petals ovate to spatulate, 1.2–2 times as long as sepals, apex rounded, entire.
on stipe 0.1 mm or shorter, broadly ellipsoid, 3.5 mm, shorter than sepals.
narrowly ellipsoid, 3.5–6 mm, equaling sepals.
brown, obliquely triangular with adaxial groove, radicle prolonged into short beak, compressed, 0.5–0.8 mm, low-tuberculate.
reddish tan, suborbiculate with radicle prolonged into beak, somewhat compressed, 0.6–0.7 mm, obscurely sculptured (50x).
= 20.
= 26, ca. 52, 78.
Minuartia glabra
Minuartia obtusiloba
Minuartia glabra, along with M. groenlandica (Retzius) Ostenfeld and M. uniflora (Walter) Mattfeld, comprise the so-called granite outcrop arenarias of the southeastern United States. These species have been studied extensively, both systematically (e.g., J. F. McCormick et al. 1971; R. E. Weaver 1970) and for pollination biology (R. Wyatt 1984).
At this time, we follow R. E. Weaver (1970) in maintaining Minuartia glabra separate from M. groenlandica. The species are very similar morpho-logically, including sharing clawed petals and obliquely triangular seeds, like those in most Sagina species but unique among North American Minuartia species; the annual versus perennial habit and, at least in the southeast, phenology and elevation can be used to distinguish these taxa. Further studies in northern populations may be warranted to resolve the question completely.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Minuartia obtusiloba, an amphi-Beringian species, sometimes forms hybrid swarms with M. arctica. Specimens labeled Arenaria sajanensis Willdenow ex Schlechtendal from western North America, sometimes referred to M. biflora (e.g., H. J. Scoggan 1978–1979, part 3), are likely to be M. obtusiloba.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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