Abstract: Understanding how plant species persist and thrive in our everchanging world involves knowing what influences seedling emergence and success. Myxospermy, or the production of seed mucilage, is related to many aspects of seed and seedling ecology and could relate to the successful establishment of some species over others. Yet the influence of myxospermy in shaping many terrestrial ecosystems remains unknown since research exploring the presence of seed mucilage has largely only occurred in dry ecosystems. More extensive surveys testing for the presence of myxospermy in a variety of ecosystems are needed. We tested for mxyospermy in plant species from wet and dry grasslands to address three research questions. First, what is the prevalence of myxospermy in temperate grasslands? Second, is the prevalence of mxyospermy related to moisture limitations or requirements of the species? Lastly, does the presence of myxospermy in grassland species relate to energy investment and ecological traits of the species?
To quantify the prevalence of myxospermy among grassland species, we measured seed mucilage production for 70 prairie species that were specialized to either dry or wet grasslands. To test for the presence of seed mucilage, seeds were incubated in an aqueous solution with a dye that stains pectins, the main polysaccharide of mucilage, purple. Seeds sat undisturbed in the plates with dye and were observed and photographed at 10 min, 1h, 2h, and 1d. Here we show that myxospermy was much more prevalent in grasslands than predicted, with over two-thirds of grassland species (64%) producing seed mucilage. Previous assessments of the prevalence of myxospermy in plant communities found much lower occurrences (10 – 27%). Contrary to our predictions, the prevalence of myxospermy was unrelated to moisture requirements of plant species, as myxospermy was equally abundant in both dry and wet grasslands. Myxospermy was also not associated with seed mass, as both large and small seeds produced mucilage. In conclusion, seed mucilage is a much more common trait than anticipated and is not more abundant in dry systems. The next step is to expand experimental testing beyond model organisms into natural systems to learn if and how seed mucilage relates to species establishment and persistence in the variety of ecosystems where myxospermy is found.
