Biology Reference
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Figure 4: Some common cyanolichens. (A) Nephroma bellum , on mossy soil. From northern interior British Columbia. (B)
Nephroma resupinatum on mossy Quercus . From the northern Sierra Nevada, California (C) Nephroma helveticum subsp.
helveticum, on mossy rock. From the North Shore of Lake Superior, Ontario. (D) Sticta fuliginosa , on mossy rock. From Shasta-
Trinity National Forest, northwestern California. Photographs courtesy Stephen Sharnoff, Missouri Botanical Garden,
University of California, Berkeley, CA, USA (http://www.sharnoffphotos.com/).
Color image of this figure appears in the color plate section at the end of the topic.
the cylindrical, upright branched portion. This is the medulla and around is the lower cortex. This
is followed by the algal zone and upper cortex. The medullary group of hyphae and the thickened
cortical hyphal threads provide the requisite mechanical strength to the thallus. The central threads
form an attachment organ at the base.
v) Reproduction : The photobiont reproduces asexually within the lichen thallus itself. Even otherwise,
the lichen thallus exhibits both asexual and sexual reproduction. During asexual reproduction,
the mycobiont and the photobiont separate from the lichen thallus and grow out to form a new
lichen thallus. The structures formed may be called as soredia, blastidia, isidia and lobules. These
are scattered by wind, animals, birds, mites, ticks and rain to new locations where they develop
into new lichen thalli. In addition to these structures, the mycobiont forms specialized structures
known as pycnidia which release conidia. These are carried out by wind currents and when they
fall on suitable substrata by the side of the photobiont, they germinate and envelope the photobiont
to again form a lichen thallus. Sexual reproduction is exhibited by the mycobiont leading to the
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