Aerial reproductive structures of vascular plants as a microhabitat for myxomycetes.

This study explored the occurrence and distribution of myxomycete species on the aerial reproductive structures of vascular plants. Eight species of vascular plants representing five families were sampled. The doubled rope climbing method was used to collect bark and cones from the canopy of Pinus echinata. Bark and aerial seed pods were gathered from Cercis canadensis, follicles and stems from Asclepias syriaca, dried composite inflorescences and stems from Echinacea angustifolia, E. pallida, and E. paradoxa var. paradoxa, and capsules and stems from Yucca glauca and Y. smalliana. Reproductive structures and bark/stems for 202 host plants were separated and cultured in 541 moist chambers, resulting in 118 collections yielding 32 myxomycete species representing 11 genera, seven families and five orders. There was no significant difference in pH values of the reproductive structures and bark/stems of the host plants, however legume pods of C. canadensis (6.9 +/- 1.3) had higher pH than the bark (6.0 +/- 1.1) and had a different composition of myxomycete species. Myxomycete orders have optimal pH ranges. Nonmetric multidimensional scaling, multiresponse permutation procedure and indicator species analysis showed a significant difference in species richness of reproductive structures and bark/stems. The bark of trees had greater mean species richness of myxomycetes than the reproductive structures, but the reproductive structures of herbaceous plants had greater mean species richness of myxomycetes than the stems. A new term, herbicolous myxomycetes, is proposed for a group of myxomycetes frequently associated with herbaceous, perennial, grassland plants. An undescribed species of Arcyria occurred only on cones of P. echinata.