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Results tagged “lichen”

Jul 30, 2014: Peltigera gowardii

Today we have a photograph of Peltigera gowardii. Richard Droker (aka wanderflechten@Flickr) took this photo looking down into a stream, and later uploaded it to the Botany Photo of the Day Flickr Pool. Thanks, Richard!

A member of the Peltigeraceae, Peltigera gowardii is a lichenized ascomycete. The cyanobacterium Nostoc forms an indistinct algal layer throughout the medullary tissues. This species is sub-erect, with a foliose thallus. The thallus is black when wet, and slate grey to black and papery when dry.

Peltigera gowardii is widely distributed throughout the mountain ranges of northwestern North America. The range extends from central/northern California northward to Oregon, Washington, and British Columbia with disjunct populations in Idaho and southern Alaska. This species is associated with older forests and watersheds on shaded rocks, often 0-2cm above water level.

It was only recently that Peltigera gowardii was described as a species. Previously, it was considered to be Peltigera hydrothyria—the morphologically similar eastern North American counterpart of Peltigera gowardii. In a taxonomic revision published in 2011, researchers reviewed Peltigera hydrothyria across North America. In addition to a molecular phylogenetic analysis, they evaluated the biogeography, ecology, morphology and chemical composition of lichens from both sides of the continent. This was to determine if they were or were not conspecific (the same species). They found that the eastern and western populations differed allopatrically (occurring in separate non-overlapping locations), chemically (the eastern group contains the secondary compound methyl gyrophorate and the western group does not), and molecularly. They also found that within the western population there were two distinct sequence types. This left them with a case where morphological characters supported a single widely-separated species, chemical analysis supported two species, and molecular data supported three species (where two have identical chemistry and overlapping ranges).

After consideration, it was determined that chemistry, biogeography, and molecular data are all in agreement in rejecting the circumscription of Peltigera hydrothyria based on morphology. It was then decided that at least one new species should be described to accommodate the western populations, and Peltigera gowardii is now recognized as a distinct species circumscribing two phylogenetic entities. More research is needed to determine if Peltigera gowardii can be further divided taxonomically (see: Lendemer, J. O'Brien, H. (2011). How do you reconcile molecular and non-molecular datasets? A case study where new molecular data prompts a revision of Peltigera hydrothyria s.l. in North America and the recognition of two species. Opuscula Philolichenum. 9:99-110).

Nov 16, 2012: Cladina stellaris and Stereocaulon tomentosum

Cladina stellaris and Stereocaulon tomentosum

Bryant is the author of today's entry:

I would like to thank Richard Droker (aka wanderflechten@Flickr) for this image of a lichen community near White Pass, Yukon. The highly branched/shrub-like species of lichen towards the upper half of the image is Cladina stellaris (formerly Cladonia stellaris) and the more coral-like species occupying much of the lower third of the image is Stereocaulon tomentosum. The vascular plant is crowberry, or Empetrum nigrum. If you think that this image looks like a miniature forest, you are not the only one. A major economic use of Cladina stellaris is for miniature trees on small scale models by hobbyists and architects alike.

Lichen communities like this one can dominate a local environment. Often forming dense mats, lichen communities can out-compete plant species for real estate by preventing seedlings from establishing themselves. Seedlings that do manage to take root may be pulled out or damaged by the repeated swelling and contracting of the lichen with changes in moisture. Lichen communities can also affect the underlying soil systems by regulating soil nutrients, retaining soil moisture, and maintaining microbiological communities.

Cladina stellaris (commonly known as star-tipped reindeer lichen) often forms large and rather dense mats in its widely distributed range. As its common name suggests, it is a major source of food for both reindeer and caribou, especially in the winter. Cladina stellaris contains the liver-toxic substance usnic acid, used in products like perfumes and antibiotics. Usnic acid has a bitter taste, which has deterred indigenous peoples from eating raw lichens. However, reindeer and caribou can tolerate the acid with the aid of rumen microorganisms. It has even been proposed that usnic acid aids in digestion by reindeer because it can be successfully metabolised by the rumen microbes. Indigenous peoples discovered that the partially digested lichen found in the first stomachs of reindeer and caribou can indeed be eaten, as the usnic acid has been broken down.

Stereocaulon tomentosum is a woolly lichen with rounded gall-like growths that contain blue-green algae. Richard has also taken a close-up image of the woolly hyphae and gall structures.

Jul 31, 2012: Letharia vulpina

Letharia vulpina

Bryant wrote today's entry:

A big thank you to Anne Elliott (aka annkelliott@Flickr) for today's image of Letharia vulpina (commonly called wolf lichen), the last image in the series on plant colour. Letharia vulpina is commonly found in dry coniferous forests across western North America, Eurasia and northern Africa. People have used this particular lichen in a number of different ways over the course of history. The yellow pigment comes from a compound known as vulpinic acid. Vulpinic acid is known to be poisonous to mammals; the source of the common name "wolf lichen" comes from its former use in Europe as a substance for killing wolves. In North America, the species has been used by the Achomawi to make their arrows more lethal for hunting.

Letharia vulpina, with its striking colour, was perhaps more widely used for making dyes and paints (a practice that continues today, though less often). Records show historical use to make dye for woollens in Scandinavia. Also, many North American First Nations made or make use of Letharia vulpina as well. The Klamath, Cheyenne, Karuk, and Yurok nations soaked (or soak) porcupine quills and other materials in a solution of the extracted yellow pigment, with the coloured objects later to be woven into baskets. The Tlingit used/use a solution made from Letharia vulpina to dye fibres for Chilkat blankets. The Apache people used a decoction of Letharia vulpina as a paint, which they made crosses on their feet when moving through enemy territory, with the belief that it made them undetectable. Coastal tribes that were located outside its native range often traded for Letharia vulpina, making it an important lichen economically as well. To read more about traditional uses of lichens, see Ethnolichenology of the World.

The act of temporarily and permanently decorating our bodies with colour is a global phenomenon that is deeply rooted in our fascination/appreciation with plant and other pigments. The role that this cultural fascination has played in the course of history is pretty remarkable. David Lee reminds us that, "...using plant extracts to dye skin and fabric was a major technological accomplishment". Unlike food or most traditional medicine, dyes are usually produced by combining a decoction with other materials that alter the chemical structure, making them bright and permanent. Soon after these techniques were developed, plant pigments and other natural dyes began to be exploited to add vibrance and colour to the people of these early civilizations. Plant pigments helped make warriors appear more intimidating, royalty seem more royal, and added beauty to those who could afford it. Some common historical plant dyes came from Rubia tinctorum (madder), Indigofera tinctoria (indigo), and Caesalpina echinata (Brazilwood). These plants and the pigments they produced were highly prized commodities that drove much of the early trade between Asia, North Africa and Europe. With increased trade also came colonization, where "the colonies provided the raw materials feeding the industrial Revolution in Europe, including fibre and dyes for the great textile mills" (Lee). In the mid-19th century, two students at the school of Justus von Liebig in Germany made discoveries that developed the artificial production of dyes. One of these students, August Kekule von Stradonitz contributed a theory (derived from these discoveries) that played a major part in the foundation of organic chemistry!

Jun 25, 2012: Pilophorus acicularis

Bryant wrote today's entry. He scribes:

I would like to thank Brent Miller, aka foliosus@Flickr and Richard Droker, aka wanderflechten@Flickr for today's photos of Pilophorus acicularis or, commonly, devil's matchstick (Brent's image | Richard's image). The genus Pilophorus is a part of the Cladoniaceae, one of the largest and most common families of lichenized fungi. Pilophorus acicularis is the most common species in its genus, and can be found along the west coast of North America (from north of San Francisco to Alaska) and eastern Eurasia.

The primary thallus, or body of the lichen, is granular and crustose, while the tall stalks (or pseudopodetia) form the fruticose secondary thallus. The stalks are usually over 5mm tall and unbranched, however there may be the occasional fork. The black apothecium, or spore-bearing structure, usually sits atop of each stalk. The photobiont (or algal associate) of Pilophorus acicularis is commonly Trebouxia magna, a species of chlorococcoidal (green and sphere-shaped) algae. More photographs of Pilophorus acicularis and related species may be seen on the excellent Ways of Enlichenment site.

Pilophorus acicularis is saxicolous (colonizes rock), and it is most often found on newly exposed silicate rock surfaces. Part of what makes Pilophorus acicularis such an audacious pioneer is that the thalli can host nitrogen-fixing "factories", in the form of cephalodia. Cephalodia contain cyanobacteria, which fix nitrogen from the air, and therefore can sustain colonies of Pilophorus acicularis on nitrogen-poor sites, like rock surfaces.

Saxicolous lichens, such as Pilophorus acicularis, play a large role in primary soil formation and primary succession. Once established on a rock surface the hyphae of the crustose primary thallus works its way in between the rock crystals and fragments along microscopic fissure lines. The action of the hyphae expanding and contracting (due to presence/absence of moisture and freezing/thawing) slowly loosens the particles of rock. Also, the hair-like structure of the secondary thallus acts much like a comb, collecting and accumulating dust and other airborne particulate. This accumulated airborne particulate, along with the decaying matter of Pilophorus acicularis itself, provides a more advanced substrate for other species (like mosses) to colonize.

Lichens have always fascinated me. Their strange forms and ability to survive and colonize in the harshest conditions makes them seem like a part of miniature alien landscapes (Pilophorus acicularis being no exception). Perhaps this thought isn't that far out; see this article from the European Space Agency about a lichen's journey into space!

Apr 26, 2012: Cladonia evansii

Cladonia evansii

One of the many highlights of our recent trip was a visit to the Ohoopee Dunes Natural Area near Swainsboro, Georgia, where Dr. Mincy Moffett gave us a tour of this uncommon ecosystem. The Ohoopee Dunes are the most extensive riverine sandhill formation in Georgia, and host a number of rare and threated animal and plant species.

One vignette of the tour was this location where Cladonia evansii, also known as powder-puff lichen or deer moss, was found in abundance. With its dense clusters of greyish-white round tufts, it looked like someone had assembled a collection of miniature tumbleweeds in the oak leaf litter (I think it's bluejack oak, Quercus incana). While we all admired the amount of this lichen in this location, Alan Cressler has a photograph of an even denser stand from a different tract of the Ohoopee Dunes: Cladonia evansii.

In the USA, Cladonia evansii is found along the coastal plain of the eastern seaboard, ranging from Texas to at least North Carolina (and perhaps even further north -- I can't tell on the map I've used). It is also found in the Caribbean. Its habitat preference is partially shaded or open ground, typically in sandy areas. Additional images are available from ForestryImages.org: Cladonia evansii and Sharnoffphotos.com: Cladonia evansii.

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