Winter is in full swing here. It was -30 degrees Celsius overnight and we’re expecting up to a foot of snow by Monday. Spring can seem far away in the depths of cold and dark but will come nevertheless. From my botanist’s perspective, spring is a magical time. As the weather warms, I watch the trees and plants for the first signs of new growth. Heat and day length both influence when plant buds burst. The first plant to bloom is usually Coltsfoot (Tussilago farfara), anywhere from mid March to mid April. To the unaware eye, they look like dandelions but there are a few key differences. First, it’s too early in the season for dandelions. Dandelions start showing up in June so the flowers you see in March can’t be that. Second, think of what a child would draw as a sun with the big circle in the center and lines as rays. Many flowers of the aster family have that general look because of their composite head (more than one flower) and can have disc (at the center) and/or ray flowers (at the edge). These species have both types of flowers, giving the look and the ray flowers look like the center of the sun. That center is much smaller on Coltsfoot than on dandelions but is very defined. Also, coltsfoot has big round, lilypad-like leaves whereas dandelions have long, deeply lobed ones. Later in the year, the leaves are often the only part you see.
Images courtesy of Wikipedia: http://en.wikipedia.org/wiki/Tussilago
The other important thing to know about Coltsfoot is that it is useful to track annual variation in climate warming trends because of its sensitivity to temperature. A study published in 2006 showed that flowering dates occurred 15 to 31 days earlier in Quebec since the beginning of the 1900. Also, urban centers are much more susceptible to earlier warming than rural areas because concrete and pavement keep the heat longer than grass and trees (urban heat island). Examinations like these have been repeated among different groups of plants and find similar, less pronounced trends.
Fagus grandifolia – American beech
Acer rubrum – Red maple
Red maple is a close relative to the sugar maple (Acer saccharum), famous for its tasty byproduct. Springtime temperature patterns are crucial to maple syrup production. It takes specific daytime-nighttime temperature cycles over several days to trigger sap flow. Temperatures about 5-10 degrees above freezing during the day returning to below freezing overnight will get things moving. If temperatures get hot too fast, the sap changes flavor because the buds have started to gear up for flowering and leaf formation. In recent years here, we’ve had early February sap runs and short seasons which can be hard on producers if they aren’t prepared. Red maple can be used for syrup production but my trees aren’t quite big enough yet. I hope to try it out in the coming years.