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Orthotrichum Moss (Orthotrichum striatum)


Orthotrichum striatum, There is a window of opportunity from late winter to early summer during which O. striatum can be identified, thanks to its capsules which are distinctively smooth after they have shed their lid. The capsules are 1.75-2 mm long, and topped by a set of 16 recurved, white outer peristome teeth, as well as 16 straight inner teeth. Unripe capsules are relatively broader than those of O. affine and sit under a short, light green, hairy calyptra. Capsules are also partly obscured by leaves that are, like all the leaves of O. striatum, very sharply tipped. The margins are recurved. The loose, branched tufts of O. striatum are 0.5-3 cm tall, usually dingy brownish-green, but may be mid-green. Leaves are about 3 mm long. After shedding their lid, the mature capsules of almost all our other Orthotrichum species are strongly furrowed. The most frequent species with relatively smooth capsules are O. rupestre (p. 655), which tends to grow on rocks rather than trees and shrubs, and has 8 erect outer peristome teeth, and the very scarce O. speciosum (Smith, p. 670), which holds its capsules well above the leaves. It is also worth checking O. striatum for two Mediterranean species: O. shawii (Smith, p. 669) lacks an inner peristome, whilst O. acuminatum (Journal of Bryology 31, 47-49) has almost no outer peristome. There are single British records of each species, but both are spreading in Europe. O. striatum is fairly frequent in western and north-eastern parts of Britain, and in some places is almost as common as O. affine. However, it declined dramatically in polluted areas, and is only just starting to reappear in most of lowland Britain. It tends to grow in small quantity on twigs of hazel (Corylus avellana) or willow (Salix), or on the trunks of ash (Fraxinus excelsior) or sycamore (Acer pseudoplatanus), and favours sheltered places.

Taxonomic tree

  • Domain: Eukarya

    • Kingdom: Plantae

      • Phylum: Bryophyta

        • Class: Bryopsida

          • Order: Orthotrichales

            • Family: Orthotrichaceae

              • Genus: Orthotrichum