Week of April 2, 2023 – April 8, 2023
by David DuBois, Land Steward
Everyone knows that spring is the time for flowers, but what is so special about this time of year that allows our woodland herbs to create such spectacular displays?
Spring represents unique opportunities in a deciduous forest. The only part of the year that is both reliably warm enough to photosynthesize and well lit on the ground, the forest floor is bathed in sunlight only lightly diffused through bare branches (versus blocked by leafy canopies). Small plants growing on the forest floor find their temperature moderated by the ground which holds heat from the day and protects against the coldest chills of spring nights. This allows low growing plants a jump start on their taller counterparts and take advantage of the available abundance of energy.
But taking advantage of this early light comes with a steep trade off. Plants need to be ready to photosynthesize as soon as conditions allow, requiring adaptations that help battle cold temperatures and capitalize on a narrow window of opportunity. Some forest plants hold leaves through the winter to be ready for the first warm sunny days of spring. Most forest herbs in Northeastern North America have an underground storage organ, such as a bulb, corm, or rhizome, and send up their leaves in the first warm days drawing from the stored energy they gathered from years past. For many of these plants there is little value in keeping their leaves through the heat and shade of summer, dying back to subterranean life shortly after the canopy leaves out in the coming months. Trout lilies, spring beauties, bloodroot, squirrel corn, and toothworts have adopted this lifestyle, and are true spring ephemerals that need to collect an entire year’s worth of energy in a few short months. This is no easy feat and is one of the reasons why these plants grow amazingly slow, taking many years to go from seeds to first blooms.
Another tradeoff is finding pollinators on cold spring days. Some species have gotten around the limited number of flying insects by forming tight mutualisms between early spring bees, which has led to many specialist pollinators where both the plant and the bee depend on each other for a successful season. Other species such as ramps have shifted their bloom time to later in the summer after their leaves have withered to take advantage of higher pollinator abundance.
As harsh as this niche seems, many plants have adopted the lifestyle, and it represents a significant and imperiled diversity of our native plants. This week the first few blooms from these amazing plants are starting at Baltimore Woods and across the region and their abundance will increase throughout the month. What early spring flowers will you see on your next visit?