Montana Field Guide

Plants: Pleurocarpous. Growing in open clumps of ascending shoots or interwoven into mats (Lawton 1971), light green to green (FNA 2014), becoming brown proximally with age. Stems 4-16 cm tall or more, few-branched or simple (Lawton 1971), the branching radial; terminal cell of axillary hair long and quadrangular to short and very narrow; possessing a central strand and without a hyalodermis; exterior pseudoparaphyllia wide (FNA 2014), occurring at leaf bases (Crum & Anderson et al. 1981).

Stem Leaves: Densely spaced and overlapping near the shoot ends, lax proximally, spreading about 45 degrees or more (Lawton 1971), developing a narrow, pointed bud at the stem apex (Flowers 1973), 2-4 mm in length, 1-2 mm in width (Lawton 1971), heart- to egg-shaped and somewhat deltoid, not pleated longitudinally (FNA 2014), slightly cupped, a little curved and twisted when dry (Lawton 1971); base widely extending down the stem (FNA 2014) but not distinctly auricled (Smith 1980); margins smooth (Crum & Anderson et al. 1981), flat or rolled up and inward (Lawton 1971); costa percurrent (FNA 2014) or subpercurrent, strong (Lawton 1971).

Leaf Cells: Laminal cells fine-walled (Lawton 1971); upper cells not much narrower than the lower cells; alar cells long and quadrangular, swollen and fine-walled, transparent (FNA 2014), larger than the cells above (Lawton 1971), the alar area deltoid and not precisely demarcated (FNA 2014); basal cells transparent, sometimes porose (Lawton 1971).

C. giganteum plants that do not develop the distinctive “spruce-like” form with successively smaller branches above may have their branches with the slender, ovate leaves confused with the stems and branches of C. cordifolium. However, the alar region’s boundary in C. giganteum is well-defined rather than gradually transitioned, the plants are occasionally light pink (never the case with C. cordifolium), and they grow in habitats lower in nutrients and slightly higher in mineral content (FNA 2014).

Calliergon stramineum resembles C. cordifolium but has an alar region that is egg-shaped and the boundaries sharply defined rather than a somewhat wide deltoid alar region with imprecise boundaries (FNA 2014).

Damp to wet, somewhat high-nutrient fens, forested swamp margins (FNA 2014), bog forests (Crum & Anderson et al. 1981), edges of wet places, waterways (FNA 2014), shallow waters (Elliott 2016), sometimes emergent or briefly underwater (Crum & Anderson et al. 1981).

Autoicous (FNA 2014) or occasionally several archegonia mixed with perigonial buds (Crum & Anderson et al. 1981). Seta 3-6 cm in height, russet. Capsule theca to 2.5 mm in length (Lawton 1971), inclined to drooping, bowed, the neck narrowed (Crum & Anderson et al. 1981); exostome with an external network of lines below and toothed above (FNA 2014), ochre; cilia knobby, grouped in 2’s and 3’s (Crum & Anderson et al. 1981).