Plants low-growing in loose mats to compact cushions, capitulum often indistinct or concealed by upwardly directed branches; pale green, straw-colored brownish to reddish. Stems with superficial cortex of 1--3 layers of efibrillose, inflated, thin-walled, non-ornamented, and aporose cells. Stem leaves much smaller than branch leaves, triangular-lingulate, border entire and broadened at base; hyaline cells rhomboidal, efibrillose, nonornamented, aporose, and usually nonseptate; hyaline cells not resorbed on either, surface. Branches strongly dimorphic, spreading branches much stronger than pendent branches. Branch fascicles with 2--3 spreading branches and 2(3) pendent branches. Branch stems green, green to brownish, surrounded by 1 layer of efibrillose, non-ornamented, inflated, thin-walled, uniporse cells with slight protruding necks. Branch leaves ovate to ovate-lanceolate, apex broadly truncate, smooth and toothed; margin denticulate; hyaline cells fibrillose, smooth or papillose, convex surface with ± 5 small to medium-sized free pores, sometimes numerous pseudopores, concave surface with large pores in cell angles; chlorophyllous cells elliptic to ovate-triangular in transverse section, completely enclosed or exposed on concave surface, end walls unthickened. Sexual condition monoicous or dioicous. Capsules 2 mm or less, with numerous pseudostomata. Spores mean diameter more than 30 µm, raised Y-mark sculpture on distal surface; proximal laesura more than 0.3 spore radius.

Lower Taxa

• Sphagnum compactum Lamarck & de Candolle
• Sphagnum strictum Sullivant

Related Synonym(s):

• Sphagnum compactum var. expositum W. S. G. Maas = Sphagnum strictum Sullivant
• Sphagnum compactum var. imbricatum Warnstorf = Sphagnum compactum Lamarck & de Candolle
• Sphagnum garberi Lesquereux & James = Sphagnum strictum Sullivant
• Sphagnum mexicanum Mitten = Sphagnum strictum Sullivant
• Sphagnum rigidum (Nees & Hornschuch) Schimper = Sphagnum compactum Lamarck & de Candolle