Where rocks are acidic in nature, G. trichophylla replaces G. pulvinata as the most commonly found Grimmia. From the lowlands up to the mountains. it forms hoary-looking yellowish green to dark green cushions and patches which disintegrate easily when dry. With some practice, it’s relatively easy to recognise this plant in the field, although it will sometimes be necessary to take some back for microscopic confirmation. It can be confused with similarly-sized species of Schistidium, which usually have at least one or two capsules immersed in the stem leaves. On the rare occasions G. trichophylla does grow capsules they are always exserted on an arcuate seta. Some hoary Racomitrium species also grow in the same places as G. trichophylla but typically are much more branched.
G. trichophylla is one of a small group of Grimmia species that produce leaf gemmae (see gallery image), although these are not always present. Particular attention should be paid to the way moist plants hold their leaves erect to spreading, an important differentiator from G. lisae, a similar, but scarcer species which has recurved to squarrose leaves when moist.
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