Northland Nature: Alders show signs of life
By the time we get to early April, a few flowers have made their appearance in the region. The early and highly welcomed crocus blossoms of yellow, purple and white reach up from flower gardens now. On sunlit west and south sides of buildings, we...
By the time we get to early April, a few flowers have made their appearance in the region. The early and highly welcomed crocus blossoms of yellow, purple and white reach up from flower gardens now. On sunlit west and south sides of buildings, we also see the yellows of the ubiquitous dandelions. These hardy aliens seem to cope with the cold very well. Not only are they the first to bloom in spring, they were also the last flower seen in the fall.
But flowers do appear elsewhere at this time. April is also a month when many of the trees have flowers. Not as colorful as those on the ground and often without the expected petals, these early trees put forth flowers of a different type.
When it comes to flowers, trees fall into three groups. Type one, the dioecious, have female flowers on one tree and male on another. Such trees will later produce seeds only on the female. An example of this is the willow.
Type two and three are monoecious. This means that male and female parts are on the same plant. With type two, the flowers are on the same tree, often on the same twig, but separate from each other. This is seen in many Northland trees such as alder, birch and hazel. Type three not only has female and male parts on the same tree, they are even in the same flower. This is seen in the showy blossoms of apple and cherry that light up the yards during May.
One of the type two trees, the speckled alder, comes to maturity now. Small trees, rarely more than 15 feet tall, they grow in swamps, marshes and other wetlands common in the Northland. Earlier this spring, we saw the developing fuzzy catkins of pussy willows and aspen. While these got our attention by opening from buds, the alder catkins were formed last fall and hung on the tips of branches all winter. Now with the proper sunlight and temperature, those long hotdog-shaped structures, that looked dead all during the cold season, burst into life. Quickly, they enlarge to nearly twice their earlier size and, with maturing pollen, turn yellow.
Hanging on the end of twigs as they do, the catkins can catch any passing breeze and carry off the pollen. Any passerby who bumps these 2-inch staminate (male) flowers now will see the yellow pollen dust. Pollen is male cells of the plant, and it drifts from the catkins with only a chance of landing on the pistillate (female) flower of the alder. These female flowers are usually nearby on the branches and look like small pine cones. By far most of the pollen will float by and not settle on the female cones. To cope with this situation, the alders and other catkin-forming trees produce huge amounts of pollen.
Pollen from alder catkins early in the north will be joined by pollen from hazel, birch, willow and aspen. Northlanders with allergies to this tree-borne dust are very aware of the catkin season before most of the rest of us. Now, in early April, we see these unusual flowers on alders as they begin the tree flowering season.
Larry Weber is author of the "Backyard Almanac" and "Butterflies of the Northwoods." He lives in Carlton County and teaches natural science at Duluth's Marshall School.