SURPRISE!
Many have commented that a video component was lacking from the hiking podcasts. I have teamed up with filmmaker/producer Grant Czadzeck (www.grantczadzeck.com) to bring you a visual botanizing experience. I'm not sure how regular this will become but let us know what you think. In the mean time, please enjoy this early spring hike in central Illinois.
For some plant species, pictures will never do them justice. I realized this when I first laid eyes on a colony of blue-eyed Mary (Collinsia verna). I was smitten. These lovely little plants lined the trail of a floodplain forest here in central Illinois. It was the blue labellum that first caught my eye. After years of reading about and seeing pictures of these plants, meeting them in person was a real treat.
C. verna is winter annual meaning its seeds germinate in the fall. The seedlings lie dormant under the leaf litter until spring warms enough for them to start growing. Growth is rapid. It doesn't take long for them to unfurl their first flowers. And wow, what flowers they have!
The bicolored blooms are a real show stopper. The lower lip contrasts starkly with the white top. It's about as close to true blue as a flower can get. Not only are they beautiful, the flowers are marvels of evolution, exquisitely primed for pollination by large, spring-hardy insects. When something the size of a bumble bee lands on the flower, the lower lip parts down the middle, thrusting the reproductive bits up against the abdomen. This plant doesn't take any chances.
Being an annual, C. verna can only persist via its seed bank. Populations can be eruptive, often appearing in mass after a disturbance clears the forest of competition. Most populations exist from year to year as much smaller patches that slowly build the seed bank in preparation for more favorable conditions in the future. Because of its annual life cycle, C. verna can be rather sensitive to habitat destruction.
Seeing this plant with my own eyes far exceeded my expectations. It was one of those moments that I couldn't peel myself away from. I love spring ephemerals and this species has skyrocketed to the top of my list. Its beauty is made all the more wonderful by its ephemeral nature. Enjoy them while they last as it may be some time before you see them again.
Further Reading: [1] [2] [3]
One of the central tenets of evolutionary science is that individuals within a species vary, however slightly, in their form, physiology, and behavior. Without variability, life would languish, remaining static in a soupy ooze somewhere in the oceans. Perhaps it may not have evolved in the first place. Regardless, observation and experimentation has taught us a lot about how variation among individuals or populations can drive evolution. Today I would like to introduce you to a tiny plant native to northern and western North America that is teaching us a lot about how mating systems develop in plants.
Meet Collinsia parviflora, the maiden blue eyed Mary. Few plants are as iconic to my time living out west than this wonderful little plant. Indeed, C. parviflora is highly variable. It ranges in size from 5 for 40 centimeters in height and produces lovely little flowers that range from 4 to 7 millimeters in length. The size range of these flowers is key to investigating variations in pollination strategies.
C. parviflora has evolved what researchers refer to as a mixed mating strategy. Populations differ in that some plants self pollinate whereas others fully outcross with the help of a variety of bees. Exactly why these plants would maintain both strategies can tell us a lot about how mating systems develop in plants. What researchers have found is that there seems to be a tradeoff.
Populations that frequently self are often located in the harshest environments. Cold temperatures and a short growing season make investing in complex floral development a risky strategy. Indeed, plants growing where environmental conditions are harshest produce smaller flowers. These small flowers pack all of their reproductive bits close together, thus increasing the chances of self fertilization. It has been found that despite the risk of inbreeding, these plants produce far more seeds than plants that produce larger flowers and experience high rates of insect pollination.
The reasons for this are quite complex and more work is needed to be certain but it would seem that this is all an evolutionary adaptation to dealing with varied climates. With wide ranging species like C. parviflora, populations can experience highly varied environmental conditions. It would seem maladaptive to focus in on one particular reproductive strategy. As such, C. parviflora has evolved a range of possible anatomies as a way of adapting to many unique local conditions. If times are good and pollinators are abundant, it makes more sense to hedge bets on sexual reproduction whereas when conditions are poor and pollinators are scarce, it makes sense to produce offspring with a genome identical to that of the parents. If they can exist in a harsh location then so can the cloned offspring.
Investigations into the mating system of this tiny plant has revealed that big things can really come in small packages. I miss seeing this species. Its amazing how these tiny little flowers can be so numerous as to turn wide swaths of its habitat a pleasing shade of blue.
Further Reading:
http://www.amjbot.org/content/90/6/888.full
http://plants.usda.gov/core/profile?symbol=COPA3