Field of Science

Hot off the Geothermal Presses

 I read this study in the latest issue of the International Journal of Plant Sciences. I thought that it was a really neat study and is an easily accessible piece of scientific literature for folks to read who are not professional bryologists.

The premise - In stressful environments, studies suggest that sexual reproduction is favored. Researchers examine this idea in mosses across a geothermal gradient in Lassen Volcanic National Park in California.

Methodology - They collected data on sporophyte and gametoecia production from species in the field. (Yeah, gametoecia. I had to look this word up. It is both the gametangia and the surrounding leaves together.) They also collected data on temperature. The collection locations were divided up into geothermal and nongeothermal sites based on the temperature measures.
Also they ran a common garden experiment with Pohlia nutans to look at whether a genetic adaptation was limiting sporophyte production or if alternatively the extreme stress was the cause of low sporophyte production.

Results - Their results indicate that there were lower rates of sporophyte production, due to lower rates of gametoecia formation at the geothermal sites. These rates for both sporophyte and gametoecia production were higher at the nongeothermal sites. When plants from both types of sites were grown in greenhouse conditions these relationships disappear.

Implications - This study does not support the idea that sexual reproduction is favored in stressful environments. It actually shows the complete opposite for this species of mosses. Sexual reproduction decreases with increased temperature stress. The authors state that the "regression between temperature and sporophyte production was not high." And go on to suggest that other stresses such as heavy metals may be involved. They discuss that other studies in fungi and mosses have shown similar patterns and cite several studies.
I was wondering whether they thought that differences in light or perhaps levels of desiccation could be an influence too.

Overall I thought that it was a really great study and a nice read. One odd fact is that they list 3M Corporation as one of their funding sources in the acknowledgements. I use a lot of post-it-notes to label and organize my research. Wonder if I could get them to sponsor one of my studies?


 One of the postcards that I got this summer prominently featured mosses from northern California. A picture of the postcard is on the right. I also took a photo of the caption on the back. Check out the portion that my friend underlined. It reads "A variety of mosses are brought to blossom by winter rains." What strikes you about this sentence? How about the word blossom? Blossoming refers to flowers, and mosses don't have flowers! This is a common terminology mistake. People are much more familiar with flowering plants and when looking at mosses they typically try to use flowering plant terms. Mosses with sporophytes are often said to be fruiting or blooming. Figuring out what word to use can be a challenge. Sporulating? Sporophyting? Usually what I say is that they are reproducing and releasing spores. Most people are familiar with reproduction and then I can go on to explain more about spores if needed. 

This might seem like I am just being picky, but using the correct word is important for making comparisons between mosses and other plants. The little sporophytes that the mosses are producing are not the same as flowers, but are actually equivalent to an entire redwood tree! I think that comparison has much more wow factor that just being a gaudy flower.

This is the other mossy postcard that I have hanging on my bulletin board, below. Kathyrn is definitely winning the moss postcard competition, having sent me both of these. The stamp on the other side of this postcard even features a moss and fern filled glen. What's that, you say you can't see the mosses on the stamp? Well they are there. Look at that moist stream-side habitat. Those trees and the rocks surrounding the waterfall must be covered in mosses!