Seed Germination of Habenaria repens (Orchidaceae) in situ Beyond its Range, and its Potential for Assisted Migration Imposed by Climate Change


Brian G. Keel

Additional Authors:

Lawrence W. Zettler Beth A. Kaplin


March 2011


ABSTRACT All orchids require free-living, mycorrhizal fungi to complete their life cycles in nature and consequently, orchid conservation must take into account both organisms. In light of climate change now underway, orchids and other plants must be capable of migrating to higher latitudes, either on their own or with human intervention (5assisted migration). In this paper, we describe the symbiotic germination of a common terrestrial orchid, Habenaria repens, in situ using seeds from a southern ecotype (Florida) placed at latitudes at and above the species’ current natural range. To recover fungi in situ, 500 nylon packets containing 25,000– 50,000 seeds were buried at 5 field sites within the Atlantic coastal plain in North Carolina, Maryland, and Virginia. After ca. 5 months, a total of 10 leafless seedlings (protocorms) were recovered from two North Carolina sites, one harboring an extant H. repens population, the other an extirpated population. These protocorms yielded mycorrhizal fungi assignable to the anamorphic genus Epulorhiza. The physiological significance of each isolate was confirmed after H. repens seeds germinated in vitro following fungal inoculation (5symbiotic germination). This study demonstrates that seeds of H. repens from a southern ecotype (Florida) are indeed capable of germinating at higher latitudes where fungi already persist. Consequently, the mycotrophic demands of orchids like H. repens might be met by assisted migration involving seed release alone.