In March, the blooms of spring seem endlessly far away, but flowers are actually closer than you may think. In fact, one of our most favorite early spring activities, tapping maples for sap, is the first sign that conditions are right for the trees to begin blooming.
It all starts when the days become warm. On those bright, sunny days when the snow begins to melt and we all shed our winter coats, the trees are preparing for spring as well. Inside a maple tree’s trunk, for example, sap has been trapped all winter, but above-freezing temperatures causes that sap to expand and press up into the branches. At night, the sap cools and shrinks, which in turn pulls water up into the trunk. The process is repeated over and over until leaves and flowers in the tree’s buds begin to develop.
While this is happening, if a person, bird or squirrel happens to create a hole in the tree’s trunk, sugar-laden sap will drip out during the day. We collect this sap and boil it down for maple syrup, but the tree keeps most of it, and uses the sugar to begin growing again. For maple syrup producers, the sap is considered “good” until the buds of the tree begin to swell—when the young leaves and flowers are developing, they create compounds in the sap that impart an off taste to maple sap. (Incidentally, most species of trees to do not have this kind of heavy sap flow, and cannot easily be tapped for sap).
When the weather is right and the buds have received enough sap, a tree’s buds will burst open to reveal leaves and flowers. The flowers of most trees, however, are not the showy cherry blossoms or lilacs designed to attract bees and other pollinating insects. Instead, these flowers are small, unassuming, and sometimes nearly invisible—you have to look closely, or you’ll miss them. These early blossoms, which may emerge even while snow is on the ground and before insects are around, rely on the wind to carry their pollen from tree to tree. Here are some of the very earliest spring tree flowers: cottonwood flowers look like fat red or yellow caterpillars (depending on whether the tree is male or female), while yellowish sugar maple and box elder flowers hang on long skinny threads. Elm flowers are green and purple, and willows change from wooly white pom-poms peeking out of the buds to yellow-tipped fuzzballs. The very first tree flowers, however, appear on silver maples—these red and yellow beauties grow in clusters high on the branches, and for me are the very first sign of spring.
When exactly a tree will flower can vary from year to year, depending on the weather, but tree species that grow along rivers tend to be earlier than others. Here at the nature center we keep track of when exactly our tree buds begin to burst open. By the end of this month, silver maples will generally have flowers, followed closely by willows, cottonwoods and box elders in the beginning of April. If you are attentive to the treetops this year, you just might see the first flowers of spring.
Join us for the following nature program. Big River, Small Fry: Getting Muddy. Thursday, March 10, 9 a.m.-noon. Get out of the house with your little one and enjoy a morning of nature activities. Drop in any time for games, stories, guided walks and more. Ages birth-6, $5 per person. Reservations required, call 763-559-6700.