Pollinating the spring ephemerals

Photo of Dicentra cucullaria by Catie Drew.


IF YOU LIVE IN ANY AREA THAT IS NATURALLY WOODED, the first native plants to come up in spring are those known as spring emphemerals. These small wildflowers take advantage of that brief period in early spring when the soil warms but deciduous trees have not yet leafed out. During this small window of time, they appear and flower before fading back into the soil again as their woodland habitat is engulfed in shade.

During this time, the spring ephemerals can't just sit there and look pretty--though they most certainly do. Their critical task is to attract pollinators so that they can set seed and ensure the survival of their species.

Getting pollinated is pretty difficult for the spring ephemerals because they can bloom only when the forest canopy is still open but can be pollinated only when it's warm enough for insects to be able to fly. If those two seasons don't coincide, they won't be able to get pollinated unless they are able to self-pollinate.

Because they do have such a tricky time getting pollinated, most of the spring ephemerals are generalists--they can be pollinated by a wide variety of insects. However some of them are adapted to being pollinated by specific insects. Trillium, for instance, has a distinct smell that attracts flies. Dicentra cucullaria, aka Dutchmen's breeches, is dependent on queen bumblebees for pollination. Some of the orchids are also very specialized.

One interesting adaptation is found in Cornus canadensis, a low-growing member of the dogwood family. The flowers of this plant are so eager to be pollinated that when an insect lands on one, it explodes with a shower of pollen that covers the insect in golden dust.

Most of the pollinating insects that visit spring ephemerals also go to the early spring flowering trees and shrubs, incidentally. Willows are especially popular because of their huge production of pollen. Maple flowers and flowering Ericaceous shrubs also seem to get a lot of attention.

But the bottom line is that they all need each other. The interactions are very complicated and poorly understood, and we don't really know which native plants and/or pollinators are essential to the survival of which other native plants and/or pollinators. All we really know is that they're adapted to each other, often in very precise ways. One of many concerns about global climate change is that even slight changes in delicate, vulnerable relationships between species such as these could have unforseeable but monumental effects.

3 comments:

jodi said...

Beautiful article, Flora! As you know, spring ephemerals are some of my favourites, especially the trilliums. There's going to be a lot more interest in pollinators this year, I think too.

Terrell said...

Just wanted to let you know we linked to this article in the March issue of Learning in the Great Outdoors. Thanks!

http://aloneonalimb.blogspot.com/2008/03/learning-in-great-outdoors-10.html

Wild Flora said...

How nice to hear from an old friend and a new correspondent via the same post! Jodi, I think you're right that pollinators may finally be ready to capture the public imagination. Terrell, thanks for the boost. I hope you'll also consider promoting the Xerces Society and its work for pollinator conservation.