By S. Fred Prince.
I was very much interested in Mr. Hill's article on the cliff brakes in
the January Bulletin. I lived at Madison, Wisconsin, from 1874 to 1878,
and have gathered _Pellaea atropurpurea_ many times from the sandstone
cliffs, not only on Lake Mendota, but also Lake Monona and outcrops in
other parts of the "Four-lake County."
I found it growing on both the Potsdam and the Madison sandstones. On
the former it was only in small clumps, or isolated plants, much more
sparse in growth than when on the latter, though I never found it
anywhere in such dense, tangled masses as it forms in the clefts of the
limestone rocks of the southwest Ozarks.
I have also found _Pellaea atropurpurea_ growing thinly, on a dark red
sandstone, at Paris Springs, Missouri, not far from Springfield.
I would like to add to the localities of _Polypodium vulgare_ in
Michigan. I found it, in the summer of 1910, growing in dense mats on
sand dunes, south of Macatawa, Michigan. The plants were in a woodland
composed principally of hemlock, with oak and a general mixture of elm,
maple, hickory, etc. When you lifted a mat of the fern, the bare sand
was left exposed. I thought the conditions rather peculiar.
I found many ferns growing on these wooded sand hills where, at the
most, there was but half an inch of soil on top of the white sand. The
list includes:
_Adiantum pedatum_; _Pteris aquilina_; _Asplenium filix-foemina_, in
marshy places between the dunes; _Polystichum acrostichoides_, very
sparingly; _Nephrodium thelypteris_, very luxuriant, like the lady fern,
in marshy ground; _Nephrodium marginale_, the most common fern;
_Nephrodium cristatum_; _Nephrodium spinulosum_, wherever there was a
rotting chunk of wood; _Onoclea sensibilis_, and _Onoclea
struthiopteris_, both very rank; _Osmunda regalis_ and _Osmunda
cinnamomea_, these last four in marshy spots; and _Botrychium
virginianum_, on the sides of the dunes.
I have been observing the habits of _Onoclea sensibilis_ for many years,
even raising plants from the spores to five years old; caring for other
plants for years, changing conditions, and varying my experiments, until
I have come to the following conclusions:
When the soil is constantly and evenly moist and unusually rich, and the
plant is constantly shaded, it tends to produce its fertile fronds
flattened out like the sterile, with all stages to those only partly
rolled up. These _unrolled_ fertile fronds do not differ from the
_rolled up_ ones, on the same plant, except in this one particular.
When a heavy screen was changed so that the plants would be in the full
light and sun, the fertile fronds produced the rest of the season were
as tightly rolled as usual, and it took two years of shading before
these plants produced open or unrolled fertile fronds again. Varying the
other conditions--moisture and nutriment, had similar results, but less
marked.
_Champaign, Ill._