Monographs Details: Timmia norvegica var. excurrens Bryhn
Authority: Buck, William R. 1987. Bryostephane Steereana: A Collection of Bryological Papers Presented to William Campbell Steere On The Occasion of His 80th Birthday. Mem. New York Bot. Gard. 45: 1-749.
Discussion:One leaf, 1.45-1.56 m. The fossil was reported as T. austriaca Hedw. (Miller & Ireland, 1978) based on the taxonomic literature then available, but reference to the recent monographic studies of Brassard (1979, 1980, 1984) shows that it is better referred elsewhere. Measurements of 25 mid-laminal leaf cells gave the following means: width = 6.1 µm (range 4.6-8.1), length = 6.8 µm (range 2.3-11.5). These correspond to comparable measurements of T. norvegica var. excurrens (Brassard, 1979), although the mean cell width is only slightly smaller than that determined by Brassard (1984) for T. megapolitana subsp. bavarica (Hessl.) Brassard., [However, the darkly colored sheath of the fossil leaf does not correspond to the hyaline or yellowish sheath of subsp. bavarica. Moreover, cell walls ofthe fossil at it the zone of leaf insertion are thinner than those imjrlmediately above and are suggestive of similar cells that lead to the characteristic leaf abscission reported for plants in extant populations of T. norvegica. Further details about this significant fossil will be presented elsewhere by m e and G. Brassard.