When faced with an unknown Schistidium, the bryophyte enthusiast has no alternative but to set about sectioning leaves with a super-sharp razorblade. Examination of the resultant transverse leaf sections is the only reliable way of seeing any laminal papillae and thus ensuring that the right course is navigated through a good Schistidium key (see the Resources pages).
Very few British and Irish species of Schistidium species have upper leaf laminae with papillae (the others are smooth, although papillae can sometimes be present on the nerve). S. pruinosum is one of these, and has leaves that look quite matt because of it.
The oft-given character of perichaetial leaves of a different shape and broader than the stem leaves is really useful to confirm S. pruinosum but the differences are not too easy to see until you strip leaves off and compare them side by side microscopically.Read the Field Guide account