Morphological characters, relative to distribution, and taxonomic considerations of the genus Climacium in North America

• Published in: Canadian Journal of Botany
• Main Authors: Horton, Diana G., Vitt, Dale H.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1976
• Subjects: Plant Science; Canada; glacier*
• Online Access: http://dx.doi.org/10.1139/b76-202; http://www.nrcresearchpress.com/doi/pdf/10.1139/b76-202

A quantitative and qualitative analysis of Climacium americanum and C. dendroides in North America confirms that these two taxa are distinct, although there is limited morphological intergradation in the region of the Great Lakes eastward to the coast. Climacium americanum has branch leaf upper cell length-to-width ratios of 3–7(8): 1, branch leaf auricles generally larger, stem leaf apices acuminate, and capsules symmetric, 3.0–6.0 mm long; while C. dendroides has branch leaf upper cell length to width ratios of (6)7–13:1, branch leaf auricles generally smaller, stem leaf apices obtuse and apiculate, and capsules usually asymmetric, 1.5–4.0 mm long. Climacium americanum is endemic to southeastern North America, while C. dendroides is western and boreal in distribution. It is hypothesized that the endemic C. americanum arose in isolation from the circumboreal C. dendroides. Upon retreat of Pleistocene glaciers, geographical intermingling of the two species resulted in limited morphological intergradation in southeastern Canada and northeastern United States. Climacium kindbergii is considered to be taxonomically synonymous with C. americanum, while C. novae-seelandiae is regarded as taxonomically synonymous with C. dendroides. Climacium japonicum is a distinct species characterized by a few large teeth on the abaxial surface of the costa of branch leaves.