Melissa K. McCormick, Dennis F. Whigham, Rachel Rock-Blake, Hope E.A. Brooks

North American Orchid Conservation Center (NAOCC) and Smithsonian Environmental Research Center (SERC)

Orchids are widely threatened and endangered worldwide, but efforts to conserve and restore them has been limited by not knowing about the pollinators and fungi they need to grow and reproduce. The absence of appropriate mycorrhizal fungi can limit where orchids grow, but little is known about how the abundance and diversity of appropriate mycorrhizal fungi can affect orchid growth and population dynamics. Light availability is also expected to affect population dynamics, but with orchid life stages occurring predominantly above- or below-ground it seems reasonable to hypothesize that different life stages would be driven by above- or below-ground factors. In particular, emergent, green, above-ground stages would be most impacted by light, while seed, protocorm, and dormant stages would be most affected by mycorrhizal fungi. We hypothesized that the distribution, abundance, and emergence of the globally rare temperate, terrestrial orchid, Isotria medeoloides, would be driven at least partly by their mycorrhizal fungi. We combined the use of specific PCR primers, quantitative real-time PCR, and spatially nested soil samples to measure the distribution and abundance of mycorrhizal fungi that associate with I. medeoloides and measurement of light availability and orchid growth in three distinct studies. We found that I. medeoloides distribution and emergence were affected by the distribution and abundance of their mycorrhizal fungi in the soil. In contrast, plant growth during the growing season and the likelihood of flowering the subsequent year were more affected by light availability. We conclude that orchid conservation and studies of the drivers of orchid population dynamics need to consider both the mycorrhizal fungi and light resources they require.

Contributing Author(s): 
Date Recorded: 
Wednesday, March 4, 2020

Brenda Molano-Flores, Illinois Natural History Survey, University of Illinois: Urbana-Champaign, Sara Johnson, Department of Natural Resources and Environmental Science at University of Illinois: Urbana-Champaign, & Janice Coons, Eastern Illinois University

Macbridea alba (Lamiaceae) is a federally threatened and state endangered perennial herbaceous mint. It is endemic to grassy pine flat woods and occupies a range of conditions from wet savannas and sand hills, to disturbed roadsides. Several studies have been conducted to assess genetic diversity, pollinators, breeding system, and seed germination in Macbridea alba. In addition, work associated with seed banking and flowering in relation to fire has only been published in abstract form making replicability difficult and most of this work has been limited to a few populations. Results from these studies point to: 1) low levels of genetic diversity, 2) need for pollinators such as Bombus spp to facilitate gene flow and fruit/seed production, 3) seed germination is high, 4) vivipary occurs, 5) seeds have limited long-term storage capacity and a lack of dormancy, 6) and flowering may decrease as time since fire increases. However, two areas that have not been fully explored are the reproductive success (i.e., fruit set, seed set, and germination) and pre-dispersal seed predation across multiple populations and their role in the long-term persistence of Macbridea alba populations. In 2019, seven Macbridea alba populations within Apalachicola National Forest were visited to better understand the reproductive ecology of the species. At each site, infructescences were collected and fruit set, seed set, herbivory, and pre-dispersal seed predation were documented. Also, information about vivipary, i.e. premature germination of the seed within the calyx, was gathered. Lastly, collected seeds were used to assess seed germination. Our preliminary results are showing variation among populations for all the metrics that have been measured. Based on these findings, we can better understand the life history strategies and reproductive ecology of this rare plant for conservation both in-situ and ex-situ in the future.

Date Recorded: 
Wednesday, March 4, 2020

GerminaQuant: Interesting Germination Analysis App

Our summer fellow pointed me in the direction of this interactive platform for seed germination analysis. I can see it being a useful instrument for producing visualizations for reports if can make the fields fit your needs. 

Setting up germination tests

I'm new to germination testing and will be running germination trials on lots of different species (mostly midwest natives). What kind of plates/containers do you use? What kind of media- agar, blotter paper, sand?) do you use and what do I need to know about keeping it watered/sterilized/labeled? 

Do you always steralize your seeds before "planting" them? If so, what protocol do you follow?

Please share your trials and tribulations! Thanks!

Solidago squarrosa germination techniques

Does anyone have experience with seed treatments and/or tips for germination of Solidago squarrosa?