Perigynia Removal Improved Germination in Two Native Sedge Species

Sedges (Carex spp.) are used in wetland restoration projects and rain gardens because of their tolerance of fluctuating water levels. For larger projects, achene propagation is the most economical. Physiological dormancy is frequently reported in sedges and can be overcome by cold, moist stratification or after-ripening. Even when physiological dormancy is relieved, germination may still take several weeks. Removing the perigynium (perigynia, plural), a bladder–like sac that adheres to the pericarp of the achene, has decreased germination time and increased percent germination of some sedges. A growth chamber experiment was conducted to evaluate perigynia removal of four sedges native to the north central United States. Yellow fox sedge (C. annectens Bicknell), porcupine sedge (C. hystericina Muhl. Ex Willd), plains oval sedge (C. brevior Mack) and palm sedge (Carex muskingumensis Schwein) achenes were collected, cleaned and after-ripened. Achenes with and without pergynia were placed into petri dishes with moistened filter paper and grown for four weeks under 12-hours of cool, white fluorescent light, with alternating 27 ^oC, 10-hour days/15 ^oC, 10-hour nights with a 2-hour transition period between temperatures. Experimental design was a completely random design with four replicates. A species by perigynia interaction occurred. Removing perigynia significantly increased percent germination of yellow fox sedge from 40% to 62% and porcupine sedge from 79% to 98%. Perigynia removal did not significantly increase percent germination of palm sedge or plains oval sedge. Time to 50% germination was reduced for yellow fox sedge and porcupine sedge but not palm sedge or plains oval sedge. Perigynia removal is an effective strategy to increase percent germination and reduce time needed to achieve 50% germination of yellow fox sedge and porcupine sedge.