The Gravel Ghost

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Look closely or you might miss it. The gravel ghost (Atrichoseris platyphylla) is a master of disguise. At home in a small pocket of southwestern North America, this wonderful member of the aster family only puts on a show when rains offer the parched landscape a momentary reprieve.

The gravel ghost is the only member of the genus Atrichoseris. It is different enough from the rest of the chicory tribe (Cichorieae) to warrant its monotypic status. The gravel ghost is a winter annual meaning its seeds germinate at some point in the fall and the plant spends most of the winter putting on growth. As you can probably imagine, life in this corner of the world is pretty tough. Rain is sparse to non-existent and many plants teeter on the edge of desiccation. The fleshy, semi-succulent leaves of the gravel ghost likely store just enough water to offer some insurance against prolonged drought.

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As if drying up wasn’t enough for this plant, the desert’s compliment of hungry herbivores are constantly on the lookout for any plant remotely alive that can offer sustenance. All it takes is a few encounters with the gravel ghost to understand how this plant manages to avoid as much attention as possible. As its common name suggests, this species blends in with the surrounding soil to an extreme degree. From what I can gather, there appears to be a lot of variation in gravel ghost leaf color depending on where the population is growing.

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Some are mostly green whereas others take on a mottled grey hue. Still others seem to have settled on a mixture of browns. It seems that no matter the substrate, the gravel ghost will do its best to blend in. Personally, I would love to see someone investigate what kind of genetic or environmental controls dictate leaf color in this species. It is fascinating to think about how plants can disguise themselves against herbivores.

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Starting in late winter and early spring, the gravel ghost needs to complete its annual life cycle. When rains punctuate the drought, the gravel ghost sends up a spindly inflorescence tipped with a few flower heads. If they are lucky, some stalks will avoid being nipped off by sheep and rabbits. Those that do put on quite a floral display. Each head or ‘capitulum’ explodes with clusters of bright white ray flowers. Only at this point does its affinity with the chicory tribe become apparent.

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The need for such a high impact floral display has everything to do with being an annual. There is only limited time for pollination and seed set. Each gravel ghost must produce enough seeds to enure that at least some survive. They simply don’t have multiple seasons to reproduction. Luckily its a member of the aster family and the opportunity for seed production is usually relatively high. With any luck, plenty of pollinators will find these plants tucked in among rocks and gravel and the process will begin again come that fall.

Photo Credit: Joey (www.instagram.com/crime_pays_but_botany_doesnt)

Further Reading: [1] [2] [3]



Meeting Blue-Eyed Mary

For some plant species, pictures will never do them justice. I realized that this week as 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:
http://bit.ly/1QfZUuD

http://bit.ly/1XD70z0

http://bit.ly/1MBrAzm