Weissia pusilla Hedwig, Sp. Musc. Frond., 64. 1801

Plants delicate, light green. Leaves linear, sometimes from slightly widened base, gradually nar-rowed, slenderly acute; costa ending just below apex; margins entire to ± crenulate; leaf cells (2-)3:1; perichaetial leaves acu-minate from ovate sheathing base. Seta 1.5-3 mm, slender, long, flexuose. Capsule oblong-ovate to ovate-pyriform when old; peristome of 16 well-developed teeth; columella immersed. Spores 10-13 µm.

Calcareous cliffs; Nunavut; Alaska, Ark., Ill., Ind., Iowa, Ky., Minn., Mo., Ohio, Tenn., Wis.; Europe; Asia.

Seligeria pusilla is a rare species with a highly scattered distribution, having occurrences in northern Alaska, Ellesmere Island, and in temperate eastern North America from Minnesota south and east to Tennessee. It has linear leaves with a relatively narrow costa that does not fill the apex. The acute leaf tips have cells that are thin-walled and somewhat longer than wide. The plants are light green and have a delicate aspect to them. Seligeria brevifolia and S. acutifolia both have differentiated perichaetial leaves whereas S. pusilla has capsules surrounded by leaves similar to (although somewhat longer than) those farther down the stem.