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California Native Plant Society –
Riverside/San Bernardino Chapter Newsletter |
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The Encelia |
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Trapelopsis bisorediata a rare tericolous lichen of Riverside County By Kerry
Knudsen The lichen flora of
California is estimated to be about 1500 taxa at this time. Due to both a
rapidly-developing taxonomy and few lichenologists out in the field
collecting in California, this number is not stable. The flora could reach a
much higher number of taxa. As it is, California has one tenth
of the about 15,000 lichen taxa recognized world wide. California is
definitely a center of diversity for more than vascular plants. Riverside County, due to a combination of factors, has many thin-soiled sites
free from weeds. These areas are scattered throughout the hills and valleys, forming openings in the chaparral and coastal sage scrub. Besides
supporting native annuals and even the Quino Cherckerspot Butterfly, these
sites support lichens that grow on soil. Many of the genera that occur are
distributed world-wide in desert and arid areas, such as Peltula, Acarospora, Psora,
Endocarpo, and Placidium. These genera are especially diverse in California, with many species endemic to southwestern North America or more rarely
California. This last year we added
from Riverside County a new species to the California lichen flora, Trapelopsis bisorediata McCune & Camacho. The Trapelopsis group includes three soil lichens in California, the most common being Trapelopsis glaucopholis (Nyl. in Hasse) Printzen & McCune. In this group,
small gray-white squamules (ca. 1mm.or less) form an imbracate thallus
covering up to a centimeter or more. They all turn red when tested with
Clorox. Trapelopsis
bisorediata is the rarest of the group
and was known from about eight sites in Washington and Idaho. It is asexual,
cloning by soredia, a ball of fungal tissue and algae produced by the
breaking down of the lichen’s thallus. I discovered the first
California location on a slope in an opening of chamise chaparral in the
Menifee Hills in Wildomar in Riverside County (Knudsen #760, UCR, ASU). My associate
James Lendemer and I were not sure it was Trapelopsis bisordiata because I observed it abrading and totally disintegrating during the
drought, something not observed in northern populations. Lendemer passed on a
duplicate to Christian Printzen in Germany who was writing on this genus for
Vol. 2 of the Sonoran lichen flora. He identified it as T. bisorediata; I had Bruce McCune verify it. Due to an electronic mix-up
the species was not included in Vol. 2 of the flora, something we all
regretted. There have been no new
collections of the species in California in the year since I collected it and
I haven’t seen it again myself so far. Because a specialist would probably
need to collect it, I am sure there are more populations in Riverside County.
Nonetheless it is not common. The rare soil lichen, Texosporium sancti-jacobi, with a similar and wider distribution in western North
America, occurs within eye sight of this species in the Menifee Hills. T. bisorediata appears to have been once wide-spread. The current cause
of its rarity is unknown. Its single location is at 578 meters; that’s well
within the zone occupied by chamise chaparral, whose success may have
severely limited suitable habitat for T. bisorediata in southern California. It should be realized that the peak of diversity
of lichens may have been far earlier than flowering plants. Thus like mosses
and bryophytes, spike mosses and club mosses, lichens may have been pushed
into microhabitats that flowering plants can’t occupy or to even have been forced to evolve to grow on flowering plants to survive. Lichens are
usually in need of exposure to sunlight and even a canopy of perennial herbs
can limit suitable microhabitats for lichens. This is why lichens are often
seen in abundance on rock outcrops raising above the local vegetation. Specimens of this lichen
and others can be viewed on request at the UCR Herbarium (951-8273601) as can
most of southern California’s native plants. Kerry Knudsen kk999@msn.com |
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OUR FEATURED PLANT |
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Kerry Knudsen at work in the field. |