April 2020 • Nebraskaland 37
protected from direct sunlight and herbivory and provided a
more consistent supply of water.
Habitats
Lichens grow on a variety of substrates, mainly bark, wood,
rock and soil, but also a few peculiar ones such as tortoise
shells and the backs of particular insects. Most species
are restricted to specifi c substrates. Some bark-inhabiting
lichens, for example, will grow only on oaks whose bark is
rough and acidic, while others will grow only on the bark of
young silver maples which is smooth and less acidic. Others
are found only on the highly resinous bark of coniferous
trees, such as pines.
Many rock-inhabiting lichens grow only on calcareous
rocks, such as limestone and marble, while other species
inhabit only non-calcareous, but silicate-rich, granite and
schist. Still others grow only on loosely textured sandstone
Shade-tolerant foliose lichens, including cracked ruffl e lichen (large, gray species on the left), hoary rosette lichen (small
gray species) and sunburst lichens (yellowish green species), cloak a Dakota Sandstone boulder in oak woodlands in Jeff erson
County. Dakota sandstone boulders located in nearby prairie support more heat- and drought-tolerant crustose lichens.
