Mycorrhizal Fungi and Cold-assisted Symbiotic Germination of the Federally Threatened Eastern Prairie Fringed Orchid, Platanthera leucophaea (Nuttall) Lindley

Abstract

The 70% decline of the Federally threatened eastern prairie fringed orchid, Platanthera leucophaea (Nuttall) Lindley, has prompted concern for its recovery through artificial propagation. We describe a technique to germinate seeds and cultivate seedlings of P. leucophaea in vitro using cold treatments (=stratification) and mycorrhizal fungi (=symbiotic seed germination). Five fungal isolates were recovered from mature P. leucophaea plants in Illinois and Michigan and were identified as members of the anamorphic genus Ceratorhiza Moore. Stratified seeds inoculated with mycorrhizal fungi germinated within 25 d of sowing. Leaf-bearing seedlings were obtained by chilling young seedlings (protocorms) for 107 d. Our successful culture of leaf-bearing seedlings with a presumed mycotrophic capability may make it possible for this threatened orchid to be propagated in soil ex vitro, followed by reintroduction into suitable habitats.