For several weeks the red flower buds of Silver Maple (Acer saccharinum) have been swelling, preparing to open and expose their flowers to the wind, their pollinating agent. While Silver Maple can have both male and female flowers on the same tree, (monoecious) it much more commonly has flowers of only one sex (dioecious). Less than 10 percent of flowering plant species have male and female flowers on separate trees — the other 90 percent combine both sexes in one plant.
The pictured branch of Silver Maple bears only male flowers, each possessing several pollen-loaded stamens. Like many wind-pollinated flowers, Silver Maple’s flowers have no flashy petals to attract insects, rather they lack them entirely, as they would only get in the way of pollen dispersal. Like other maples, if fertilized, the female flowers develop winged fruit referred to as samaras. Silver Maple samaras are larger than those of any other native maple species.
Moles are digging, Woolly Bears are emerging and preparing to pupate and develop into Isabella Tiger Moths, and Painted Turtles are emerging and warming their cool bodies by basking in the sun. Red-winged Blackbirds, Killdeer and Wood Ducks are back. Silver Maple buds are beginning to swell. Ticks are out and about. New signs of spring are appearing on a daily basis, and those of us who keep nature journals are busy recording our discoveries. These events may happen every year, but they never get old.
Studies based on the records that Henry David Thoreau and other naturalists kept for Concord, MA in the middle of the 19th century have found that the flowering of plants, leaf-out, butterfly emergence and the arrivals of some migratory birds are occurring earlier now than they did 165 years ago — anywhere from a day to three weeks earlier depending on the species — driven mostly by warmer spring temperatures. Since the mid-1800’s Concord has lost roughly a quarter of its wildflowers while an additional third have become rare.
Whether it be through a written journal, sketches, photographs, videos or taped voice recordings, the observations we make today are a valuable resource for phenology (the timing of biological events) and climate change studies and for our own personal histories of natural places we visit year after year. We are so fortunate that the current state of the world doesn’t prevent our appreciation of and participation in this annual spring ritual.
Early in spring, often in March, long before trees begin to leaf out, the swollen red buds of Silver Maple (Acer saccharinum) begin to open, revealing the flowers within. Typically, most of the buds on a given tree bloom at the same time; in fact, if there are several Silver Maples in an area, they will usually all flower within days of each other. Most of the flowers on any given tree are of the same gender, so there are male and female trees.
The flowers of maples are wind-pollinated and lack petals (which would hinder dissemination of the pollen). Therefore, the flowers are not large and flashy, and often escape notice. Flowering before leaves emerge also enhances pollen dispersal. The flowers are generally either male or female. If you look closely at the male flowers, what you will see are bundles of stamens, sometimes red and sometimes yellowish-green, tipped with yellow pollen. Female flowers have reddish clusters of pistils forming clumps of bristly little balls along the branches. The pistils develop petal-like extensions at the tips called stigmas, which are receptors for the pollen. (Photo: Silver Maple buds opening; inset = male Silver Maple flowers)
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Silver maple (Acer saccharinum) is second only to skunk cabbage when it comes to early spring flowering. Even with our nights still well below freezing, silver maple trees are bursting with blossoms. This close relative of red maple bears its male (pictured) and female flowers separately, sometimes on the same tree and sometimes not. Silver maple’s sap can be tapped and boiled into syrup, but the yield is much less, and it’s only about half as sweet as that of sugar maple.