2.2 Culture in the laboratory
Before the treatments, we propagated all field populations of S. cataractae and C. purpureus in a growth chamber for several months to eliminate the physiological stress history of the plants, i.e. carryover of environmental effects. We carefully cleaned gametophytic tissue of S. cataractae under the dissection microscope using deionized (DI) water and a brush, cut it with a razor blade, and spread each population into 4x4 cm pots containing a 2:1 mixture of clay (Turface) and commercial soil.
For C. purpureus , we sterilized gametophytic tissue of the field collected population, Cp1, using 0.2-1% bleach with shaking for 1-2 min, rinsing the tissue in sterile water with shaking for 1 minute, and spreading it into 9 cm petri dishes containing 30 ml of BCD growth medium solidified with agar (Cove et al., 2009). Under the same conditions, we propagated one additional population of C. purpureus split into male and female plants growing separately (Cp2.m and Cp2.f respectively), donated by Dr. Stuart McDaniel from the University of Florida (Gainesville, USA).