Caespitose Rockmat - Petrophytum caespitosum
(see State Rank Reason below)
State Rank Reason (see State Rank above)
Very common on calcareous rocks in Montana and elsewhere. A widely ranging species in the interior west. Rare in some outlying stations, but common in its core range.
Mat-forming shrub. Stems branched, prostrate, clothed in old leaf bases; erect stems scapose, 3–10 cm. Leaves basal and cauline, exstipulate, short-petiolate, oblanceolate, glabrate to sericeous, entire, 3–12 mm long; cauline reduced, bract-like. Inflorescence a dense, cylindrical raceme, 1–4 cm long. Flowers perfect, 5-merous, perigynous; hypanthium cup-shaped, sericeous; sepals 1–2 mm long, deltoid; petals white, 1.5–2.5 mm long; stamens 20 to 40; styles usually 5. Fruit a 1- to 2-seeded follicle, ca. 3 mm long (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX
Crevices of cliffs and rock outcrops, usually on limestone; montane to alpine (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX