Minuartia rubella (Wahlenb.) Hiern
Habitat: Calcareous or magnesian rocks and gravel. [Conifer forest (forest, upland); Rocky summits and outcrops (non-forested, upland)]
Range: Circumboreal, locally south to Newfoundland, Quebec, northern New England, and in Rockies to Arizona.
Aids to Identification: Delicate flowering stems with opposite leaves rise to 25 cm above more prostrate sections crowded with pointed, 3-ribbed leaves 0.4-1 cm long. The star-shaped flowers have 5 white petals alternating with 5 acute sepals, which are 3-4.5 mm long and 3-nerved. In the Maine form of this polymorphous species the petals and sepals are the same length. The plants form a dense, sprawling mat of foliage with abundant but tiny flowers.
Ecological characteristics: A perennial herb usually associated with calcareous or magnesian rocks ranging from alpine serpentine barrens to sea cliffs to dry open slopes in the Rockies. The Maine station for M. rubella is on shaded cliffs of syenite granite from which calcium is apparently weathering.
Phenology: Flowers over a long period: flowers and fruits July - August.
Synonyms: Arenaria rubella (Wahlenb.) Sm.; Arenaria verna L. var. rubella (Wahlenb.) S. Wats.; Tryphane rubella (Wahlenb.) Reichenb.
Known Distribution in Maine: This rare plant has been documented from a total of 1 town(s) in the following county(ies): Aroostook.
Reason(s) for rarity: Disjunct from principal range, southern range limit. Habitat naturally scarce.
Conservation considerations: The single known population appears to be well established and is in a remote location, not particularly vulnerable to human activities.