Resolving the Green Mass

by Carl Strang

How do you perceive the wild landscape around you? There’s no correct answer to this question. Even professional ecologists wear blinders or, at least, view the world through the filters of their experience and biases. Speaking for myself, as a terrestrial vertebrate ecologist I am ignorant of much of what is going on beneath the surface of the water. I can sympathize with those who view vegetation as an undifferentiated green mass.

However, I have spent some time studying insect-plant interactions. I have seen how plant-eating insects are dietary specialists to various degrees, and the literature has enlightened me on how plant chemical defenses force this specialization. Insects that eat forbs typically are limited to a single species or group of closely related species. Because woody plants commonly defend themselves with tannins, insects that go after woody plants often have broader diets. Such patterns enrich my understanding of ecosystems, and inform my understanding of vertebrate ecology. Animals which eat plants or insects are influenced by what is going on between plants and insects. Plant diversity leads to insect diversity leads to terrestrial vertebrate diversity. A consequence of all of this is that I have learned to identify woody plants and forbs, and so no longer view those many kinds of plants as a green mass.

Now I am trying to go farther, by studying the non-forb herbs. I want to improve my understanding of grasses, sedges and other plants of that ilk. It begins with learning to identify them and grasping their local biodiversity. The process particularizes the remaining green mass. Lately I’ve been focusing on sedges at Mayslake Forest Preserve. I found a species with an amazing ecological range, from partly shaded woodlands to open prairies and marsh edges.

This I have identified as the common wood sedge, Carex blanda. If I am correct in assigning all these plants to this same species, the ones growing in more open environments are a little larger, and the clusters of male flowers at the ends of the stalks are on slightly longer stems. Note that the female flowers are segregated onto separate clusters below the male flowers.

Another sedge is somewhat more restricted ecologically, and so is less common.

This one keys to Carex pellita, the broad-leaved woolly sedge. Again the male and female flowers are segregated, but the scale is larger, so that the plant is taller, the flower clusters longer. The plant also is more erect in its stance. This species is limited to edges of marshes and wet prairies at Mayslake.

Another marsh edge species remains unidentified.

Here each flower cluster contains both male and female flowers, the females at the tips and the males below them.

This one would key strongly to Carex sartwellii, the running marsh sedge, except that it appears to grow in tufts rather than from runners. I hope to get some resolution as the seeds mature. The point is that I am gaining enlightenment about the diversity and habitat specificity of this group of plants. Bit by bit, the green mass is resolving to a mosaic of separate species, allowing me to build an increasingly sophisticated understanding of the Mayslake landscape.

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