3. Splachnum luteum Hedwig, Sp. Musc. Frond. 56. 1801.
Plants light green or yellow-green. Stems 1.5-3.5 cm. Leaves somewhat crowded at stem apices, oblong-obovate, 5-6 mm; margins bluntly serrate to subentire distally, indistinctly bordered; apex slender-acuminate; costa disappearing in acumen somewhat before apex. Seta greenish yellow to orange-red, 2-15.5 cm, slightly twisted. Capsule urn orange-brown, 1-1.5 mm; hypophysis bright yellow, discoid-umbrelliform, much wider than urn, smooth; operculum hemispheric, blunt; exostome teeth inserted below mouth, approximate in pairs, orange-brown. Spores subspheric, 7-9 µm, yellow-green.
Capsules mature spring-summer. Dung of large boreal herbivores (such as moose), muskeg, boggy habitats; low to high elevations; Alta., B.C., Man., Nfld. and Labr. (Labr.), N.W.T., Ont., Que., Sask.; Alaska; n Europe; Asia.
The bright yellow hypophysis on a long seta of Splachnum luteum gives this moss the appearance of a flower. The hypophysis is discoid-umbrelliform, unlike the more convex-umbrelliform hypophysis of S. rubrum, and 4.5-11 mm wide. Immature sporophytes look much like the mature sporophytes of S. sphaericum or immature sporophytes of other North American species of Splachnum. The oblong-obovate leaves with bluntly serrate margins that narrow abruptly to a slender acumen, however, help distinguish S. luteum. Splachnum luteum is generally rare although locally common in central Alaska; the plants are often found growing on the same patches of dung with S. sphaericum and sometimes S. rubrum.