The coasts of The Great Lakes are Michigan's biggest recreational
attraction. I am beginning to see them as Michigan's greatest botanical
attraction as well. The fresh-water dune ecosystem contains most of
Michigan's rare, endangered, and unique plants. The dunes offer about
the only topography on the lower peninsula, and the stiff wind off the lakes
helps drive back the biting flies and stifling humidity ubiqitous to the
rank & foliage!
While every beach site I visited was different, the better-developed
beach ecosystems consisted of a series of low dunes with moist basins
(interdunal swales). The dune zone spans the area from the lake shore to
the forest, which starts abruptly. The forest often covers over
larger ancient dunes which create a hilly aspect. Sphagnum bogs or marshes
may occur in the forest valleys.
The dunes & swales closest to the lake are often the driest.
Cirsium pitcheri and Houghton's goldenrod grow around the dune crests,
while the swales bristle with Carex/Juncus/Scirpus, and sometimes Typha.
In the wetter swales Utricularia cornuta and U. intermedia were common
and in bloom.
The best sites for carnivorous plants exist in the final swale at the
edge of the forest. The dunes on the beach side of the innermost swales
are often covered with a screen of shrubs. These swales, when flooded
with a few cm of water over an ashy-colored sandy muck, form what I
believe is called a marl bog (I'll have to check that peatlands book).
At any rate, this is habitat for the marl-loving Drosera linearis. Although
no sphagnum grows in these areas, Sarracenia purpurea, Drosera linearis,
Drosera rotundifolia, Utricularia cornuta, U. intermedia, and Pinguicula
vulgaris all can be found together here. Orchids also add to the botanical
interest. I discovered Calopogon pulchellus, Pogonia ophioglossoides, and
Cyprepedium reginae blooming around these sites.
The Utricularia spp. and D. linearis tend to grow in the flooded
muck (a little like quicksand without the sucking force!) The pitcher
plants, D. rotundifolia, and orchids typically grow on mossy hummocks
rising above the water line. Pinguicula seems to have finicky tastes
with substrate. It grows on slightly drier areas above the water level on
sandy muck which has been stabilized by rocks and/or mossy cover. I also
found the Pinguicula proliferating along cracks of rotted wood or boards
lying in the bog. Pinguicula was uncommon and I found it in only two sites.
All had finished flowering for the season.
The very best marl bog site I found does not occur in a swale but in a
small protected bay. Perhaps a sand bar further out separates this bog
from the lake, but I did not wander out that far. Close to the forest
edge were stands of Pinguicula growing with the threatened Dwarf lake iris
(Iris lacustris). Sarracenia, Utricularia cornuta, U. intermedia, D.
linearis,and D. rotundifolia are all plentiful in the bog. Since D. linearis
and D. rotundifolia grow here in large numbers and close proximity, I set
about searching for the hybrid D. X anglica. I found a few small plants
of questionable lineage, but after about a half-hour of searching I found
a fine mature specimen, undoubtably a hybrid. I did not find D. X anglica
at any other site.
Within the forests I found the occasional sphagnum bog. Here Sarracenia
purpurea, Drosera rotundifolia, Utricularia intermedia, and U. macrorhiza
could be found. Cyprepedium reginae also occurs here, together with
Cyprepedium calceolus.
This was a great trip. I found much of Michigan's carnivorous flora
and many of the state's showiest orchids. The biting flies were a
constant annoyance, but the weather was sunny and offered perfect
photo opportunities.
Michael Chamberland