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Cottonwoods are widespread in Southeast but tend to occupy specialized habitats. They usually colonize disturbed sites early in vegetation succession, so we see them most commonly on floodplains, unstable drainages low on avalanche slopes, and in damp places that have been recently deglaciated. In Juneau, they are common in Sheep Creek valley, along Perseverance Trail, near the Mendenhall Glacier and along major rivers.

In spring, the sticky, resinous covers on the leaf buds and emerging leaves send a wonderfully refreshing aroma wafting into the air. Bees are reported to collect the resin and carry it to the hive as an anti-infectant and as cement to surround and isolate foreign objects and help waterproof the hive.

The pale golden-green of the emerging leaves makes a happy contrast with the dark conifer background. The new leaves often have a pair of "glands" at the base. Such structures on other plants usually secrete nectar, which attracts ants that help defend the plant against natural enemies such as leaf-eating insects. Ants aren't very common in Juneau, however, so it is not clear what purpose those nectaries might serve here.

The mature leaves of summer shimmer as they move in the wind, glossy and dark on the upper surface and paler underneath.

But the most enchanting visual treat happens when the little round seed pods, borne in clusters called catkins, open and expose the white cottony fluff attached to the seeds. The fluff on each tiny seed is a parachute that gives the seed a way to drift on the wind away from the parent plant. The chance of landing in a good spot for germination and growth are exceedingly small, and over 99 percent of the seeds die. The parent tree, however, on a sunny day is a stunning sight while the seed pods are ripe and open: The leafy crown of the tree gleams a pale gold, adorned with silvery tassels - altogether worthy of the elvish forest of L—rien in J.R.R. Tolkien's book "Lord of the Rings." Because cottonwoods have separate sexes, this splendor is seen only on female trees.

I am not the only one to revel in seeding cottonwoods. Black bears climb to the very treetops to munch on the catkins, scrambling to the ends of branches to harvest one catkin after another. The red squirrel that lives outside my kitchen window harvested piles of catkins and stored them with its stash of spruce cones. As they dried, they opened and created a skirt of white cotton around the base of the squirrel's favorite perch. The squirrel seems to eat some of them every day. And I sometimes see scattered piles of white fluff along a trail, where some rodent has chewed away the seeds.

In fall, cottonwood leaves turn all shades of gold and bronze, again making a pleasing contrast with the green of spruces and dull brown of alders. Even in winter, the dark, barren branches create intriguing visual patterns against a snowy backdrop.

At the upper end of Lynn Canal, our black cottonwood hybridizes with the equally aromatic balsam poplar of the Interior and some taxonomists merge the two into a single species. Cottonwoods have been used medicinally in many ways in Native cultures - the shoots and buds are said to contain antioxidants and have some antibacterial and pain-killing activity.

• Mary Willson is a retired ecology professor and a Trail Mix board member.