Growth rate of the aquatic moss Rhynchostegium riparioidesin Northern England

SUMMARY 1. The rale of shoot growth in Rhynchostegium riparioides was measured at monthly intervals over a 12-month period at four upland sites in the Northern Pennines. Changes were recorded by observations attached pieces of cotton. Detectable growth was found in each month, with the maximum in spring (up to 2.31 mm week⁻¹) and minimum in winter (1.12 mm week⁻¹); there was a second smaller peak in the autumn.
2. Growth rate was related strongly to several environmental variables, including spot measurements of water temperature (positive) and mean monthly precipitation (negative). A regression equation based on these two variables accounted for 5% of the variation recorded.
3. Total shoot growth over the 12-month period ranged from 33.4 to 73.3 mm, corresponding to an increase in mass of 22.9 and 120.8 mg, respectively.