By Greg Lecker
As I walk towards Green Heron Pond, I hear the faint music of Winter Lights, the Arboretum’s outdoor light experience. A light film of ice has formed across the pond. In denial of the coming winter, I now remember that ice making happens overnight, while we sleep snug in our beds. The wood chip path doesn’t quite crunch underfoot; but I can feel through my soles that the wood and ground is giving up its flexing. Fortunately, paths are still ice and snow free. Some feet (or rather hooves), are blissfully unconcerned about the surface on which they trod.
The garden plants are lucky that the deer exclusion fencing is erected. Only several feet outside the fence, deer have been walking – and enjoying a drink.
Just below the Snyder Building, the original visitor center, sits this little pond. Oak leaves floating on its surface. The thinnest layer of ice has formed at the outlet of a drainage pipe from where I survey this view.
Duckweed grows on this small pool next to Green Heron Pond and within the bog to the east. Duckweed is a tiny, floating green plant consisting of a leaf or a cluster of leaves with one or more roots dangling down into the water. Duckweed grows only on small still water bodies, not on larger waters that are disturbed by wind and waves. In still water, Duckweed reproduces rapidly; and it may cover the surface of the water, shading out submerged plants. Waterfowl and marsh birds eat duckweed. It also supports insects that provide food for fish. From a distance, Duckweed may be mistaken for algae; but unlike algae, Duckweed plants are not connected. Algae can grow both below the surface of water and on the surface of water; whereas Duckweed only grows on the surface of water.
Moss: Consider the levels of plant development or evolution. From lower to higher, plants advance from green algae to mosses (no roots) to clubmosses which possess both a vascular system and roots. More advanced still are seed bearing and flowering plants. Moss is one of the most primitive of land plants – a “step” above water-dwelling algae. Mosses form a “bridge” between water and land. Moss conducts water and nutrients across its surface rather than conducting water and nutrients through itself as other plants do. Mosses are far more than mere “decoration” in the woods – not just the “carpet” of the forest floor. Mosses fill a particular niche. Above all, or more appropriately, below all, mosses grow on surfaces – surfaces of rocks, bark of trees and logs, on the crust of soil or sand – similar to lichen. In this “boundary layer” within just a few centimeters or an inch or two of surfaces, air speed and temperature are moderated; and the growing environment is either warmer or cooler than extremes found further away.
It is blessedly calm this morning. A visitor might suspect that there is not much to look at. Subtlety is nature’s sonnet now. Don’t miss her interlude between leaf and snow!
Greg Lecker is a Minnesota Master Naturalist Volunteer.