Plagiothecium denticulatum var. undulatum Geh.

Plagiothecium denticulatum var. undulatum R. Ruthe ex Geh., Revue Bryologique 4: 42. 1877. ≡ Plagiothecium ruthei Limpr., Die Laubmosse Deutschland, Oesterreichs und der Schweiz 3: 217. 1897 ≡ Plagiothecium denticulatum var. majus fo. undulatm (R. Ruthe ex Geh.) C. E. O. Jensen, Skandinaviens Bladmossflora 494. 1939 ≡ Plagiothecium ruthei subsp. eu - ruthei Giacomini, Istituto Botanico della R. Università R. Laboratorio Crittogamico Pavia, Atti 4: 278. 1947, nom. inval. Type: près de Barwalde, dans la Nouvelle-Marche, R. Ruthe, 1873. Description. Plants medium-sized, light green, glossy; leaves complanate, transversely undulate, ovate to ovate-lanceolate, asymmetric, with one rounded and one flattened side, shrunken when dry, 2.0–2.5 × 1.0– 1.2 mm (Fig. 1 C); the apex acute to acuminate; margins denticulate near the apex or not; laminal cells 100–160 × 10–17 μm at the midleaf (Fig. 1 F), cell areolation quite loose; decurrencies very long, consisting of 2–3 rows of rounded to rounded-rectangular and inflated cells; capsule inclined. Distribution. Asia (China, Japan, Russian Federation); Europe (Austria, Belarus, Bulgaria, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lichtenstein, Lithuania, Luxembourg, Montenegro, Netherlands, Poland, Romania, Slovakia, Spain, Sweden, Switzerland, Ukraine, United Kingdom); North America (Canada).