Abstract
Growth-rate curves for Silene acaulis, a pioneer tundra cushion-plant species, were constructed for the Front Range of north-central Colorado [USA] by (1) measuring the diameters of 27 plants on moraines at the front of Arapaho Glacier in 1985 and 1987, and (2) measuring the largest cushions on seven historically dated substrates 9 to 82 yr old. Both curves are sigmoidal. Growth begins slowly, accelerates to a maximum rate of 2 to 3 cm yr-1, and then decreases. A lifespan of a century or less makes Silene acaulis unsuitable for dating Little Ice Age moraines in Front Range cirques. The species, however, can provide minimum age estimates for landforms and erosional features younger than 75 to 100 yr.