Remnant of a Carboniferous Forest
To the
horsetails growing along the shore of the Clinch River, the ancient Arcto-Tertiary forest
that gave rise to our cove hardwood community was a recent
upstart. Horsetails’ long slender shoots look like rushes, but
the plants are actually close relatives of ferns --- and of the plants
that dominated our landscape 300 million years ago during the
Carboniferous Era.
Once again,
there were no dinosaurs present, this time because dinosaurs were not
yet a twinkle in their father’s eye. Instead, the animal life at
the time consisted of insects and spiders, including dragonflies with
three foot wingspans. The climate was wet and hot, similar to
tropical rainforests today, but only the most ancient plants were
present. Ferns, clubmosses, and horsetails dominated the
landscape, with relatives of all three growing to tree height. I
like to try to imagine our Common Horsetail growing dozens of feet
tall, pushing up toward the sky between ferny fronds of other
species.
If plants could
tell stories, the horsetails along the River Trail would tease us with
tales of their many-times-great-grandparents whose bodies fell into a
massive swamp, pushing down the fallen trunks of horsetails below
them. Unable to decompose quickly underwater, the massive remains
of ancient horsetails and their relatives were pressed together into
coal. All of the coal mined in southwest Virginia began as
ancient plants, living and dying in Carboniferous swamps 300 million
years ago.
Nowadays, ferns
and horsetails are small herbs scattered sparsely across the forest
floor. What happened to make the massive ferns disappear?
Scientists tell us that different plants came along that were able to
reproduce better and faster, pushing the ferns and their allies to the
margins. Ferns and horsetails reproduce using spores, which look
like dust to the naked eye and have no room for storage of nutrients to
give their offspring a jump-start on life. When conifers
developed, their large seeds gave them a marked advantage over the
ferns, allowing conifers to sprout in harsh habitats where tiny fern
seedlings would never have been able to gain a foothold. Of
course, even conifers are not our most common plants now --- they were
soon overshadowed in turn by flowering plants, a group that encompasses
most of the plants on Sugar Hill. Flowering plants produce showy
blooms, most of which attract insects to move their pollen from plant
to plant, resulting in even more efficient reproduction. And so
the Common Horsetail ended up a historical side note, diminutive
relative of the plants that dominated the moist Carboniferous forests.
Not
picured:
Common
Horsetail
Scientific
Name: Equisetum hyemale
Family:
Equisetaceae (Horsetail Family)
Habitat:
Wet woods and swamps
Spores:
May to September
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