Species description:
Genus name an ancient Greek name for moss. Species name referring to the spiny teeth of the leaf margins.

Reproduction:
Sporophytes frequent, maturing in late spring to sum­mer; seta red-brown, sporangium light brown when mature, peristome mouth and teeth red-brown.

Distinguishing characteristics:
This Mnium usually has sporophytes, is usually on humus or at tree bases and the leaves differ little whether wet or dry. Under the hand lens the pairs of teeth on the leaf margin are distinctive. The mouth of the sporangium also turns dark brown well before the sporangium ripens, a feature unusual in Mnium. The red-brown peristome teeth are also characteristic.

Habit:
Loose, bluish-green to dark green turfs of unbranched shoots attached to the substratum by red rhizoids, the upper leaves often forming a rosette.

Similar Species:
The double-toothed, differentiated margins of the leaves separate the genus Mnium; of the local species of this genus, M. ambiguum, M. arizonium, M. marginatum and M. thomsonii are possible to confuse with M. spinulosum. M. arizonicum and M. thomsonii are usually less than half the size of M. spinulosum and are normally not forest-floor species. Peristome teeth are yellow in M. thomsonii; they are red-brown in M. spinulosum. M. ambiguum and M. marginatum tend to have the leaves contorted when dry, are more frequent on rock rather than humus and are found in more humid sites than M. spinulosum, a species of well-drained humus or logs. Microscopic features are more reliable but these pose some difficulties to a beginner.

If more than one illustration is available for a species (e.g., separate illustrations were provided for two subspecies) then links to the separate images will be provided below. Note that individual subspecies or varietal illustrations are not always available.

Illustration Source:  Some Common Mosses of BC