Carleton Externs Update

Hi flog,

Things have really gotten going, here at Echinacea headquarters. Julie, Sarah, Lea, and I have been spending much of our time cleaning and counting Solidago, and we’ve made pretty good headway, each counting about 2-3 samples per hour. We’ve also made some preliminary observations about variability. We’ve found high variability between plants, but not within plants! For example, we’ve seen ranges of 3 to 372 heads per stalk, and anything from 7 to 24 achenes per head in different plants. But within a plant, achenes per head is relatively uniform, generally ranging by ~2 achenes, which should allow Lea to precisely estimate total number of achenes per plant.

In addition to the Solidago, we’ve been working on Liatris. We finished the most important part of estimating potential reproductive success: x-raying the achenes to see if they contain seeds. This process involves placing baggies filled with Liatris achenes over a reusable x-ray film, shooting x-rays through the achenes, and quickly feeding the film through a machine that digitizes the film and allows for online counting of full and empty achenes. From this, we can estimate proportion of achenes containing seeds, multiply this proportion by number of achenes, and thus estimate reproductive potential of the plant. Because my project doesn’t involve seed set, Julie will be doing all the counting for Liatris (Fig. 1) while Sarah will handle counting for Solidago x-rays.

Until next time,

Tris