Improved Germination of Two Sphaeralcea A. St.-Hil. (Malvaceae) Species With Scarification Plus Stratification Treatments

Mechanical scarification plus stratification was most effective in improving germination of Sphaeralcea ambigua A. Gray and Sphaeralcea coccinea (Nutt.) Rydb. (Malvaceae) in my experiment that compared 4 seed treatments. The pattern of species response to treatments was similar. The control treatment (seeds left at room temperature in original packing envelopes) and the 30-d stratification at 4 °C (39 °F) treatment both yielded low germination (average 12%). Mechanical scarification alone improved germination (average 44%); while the combination of mechanical scarification plus 30-d stratification resulted in an average 65% germination (45% and 85% germination for S. ambigua and S. coccinea, respectively). Although impermeability of the seedcoat is the main factor preventing germination, embryos also appear to be partially or conditionally dormant. These treatments may have potential for other Sphaeralcea species.