Magnificent leafy moss (Plagiomnium venustum) is a common moss in coastal British Columbia that I would often see growing on the trunks of trees in damp forests such as big leaf maple. It is a beautiful moss that is part of a large group of mosses that all use to belong to the genus Mnium but has since been split into three genera Mnium, Plagiomnium and Rhizomnium. Each group is more or less defined by whether or not they have toothed leaf margins, and if true, are the teeth single or in pairs?  Rhizomnium lacks teeth and Mnium has teeth in pairs, and Plagiomnium has single teeth along the leaf margins.

The teeth on the leaves of magnificent leafy moss are very prominent and are visible with a hand lens. It gives the leaves a spiny look.

Like most species of Plagiomnium (as well as the other two genera), the leaves are often bordered by one or more rows of narrow linear cells. This is in sharp contrast to the round or square cells full of chloroplasts that make up the bulk of the leaf.

When moist, the leaves spread out from the main stem and the plants look very attractive with their large spiny leaves.

But when the plants dry out, the leaves are twisted and contorted giving the moss a much different appearance.

This species is much less common in the BC Interior so I was very surprised to find a clump of this species growing near the base of Batchelor Hill on soil in the Lac du Bois grasslands – a much different environment from where I saw it growing on the coast!

It is an endemic species confined to western North America.