Another checklist this on the lichens identified on my property which as of July 1, 2016 is at 70 species from 44 genera. Besides the species identified there are several specimens of crustose (crust-like) forms identified, some with reservation, to genus only. These are Bacidia, Buellia, Lecidella, Mycobilimbia, and Placynthiella. There is also a large group that I have not yet identified even to genus. The number in this group stands at 40 distinct lichens from crustose to foliose (leaf-like) to fruticose (bushy) types.
Identifying lichens requires careful observation of form (crustose, foliose, fruticose), color (both wet and dry), textures and other characteristics of the upper surface like spots and fissures, characteristics of the lower surface like color, texture, and any outgrowths, color of the interior of the lichen, and presence or absence of any spore producing bodies including their shape, color, and position. Use of a millimeter ruler is also important for measuring widths of various parts of the lichen body.
Many physical characteristics of lichens are best observed under magnification. 10x magnification is usually best unless trying to observe spores in which case a microscope is essential especially for many crustose lichens.
Chemical reagents (chlorine bleach, a potassium hydroxide solution or lye) are used to test for lichen substances which are phenolic compounds produced by many lichen-forming fungi. These compounds are often crucial in separating similar species or genera. Ultraviolet light is also helpful in lichen identification as many lichen substances are fluorescent.
My interest in lichens goes back many years when I was trying to learn certain listed rare species for biodiversity inventory work. It was not until the last 10 or so years that I began a more intensive effort to learn more of them especially the ones growing on my property.
There are an estimated 700 species of lichens in Minnesota. Many are very common and can be found growing in almost every county in the state. Flavoparmelia caperata (green shield lichen) is one such species and grows on coniferous and deciduous tree bark and on rocks. Xanthoria fallax (sunburst lichen) is also common on hardwood trees like aspen and willow. Another common and easily identified species is Physcia millegrana (rosette lichen) which does well on the bark of deciduous and coniferous trees in many environments even in cities.
Some lichen species in Minnesota are uncommon or only known from a handful of sites. These rare species are also usually specialized and require specific rock or tree bark substrates. The pH and chemistry of the substrates may be limiting factors for these species. Some species in the state are rare because they are at their known range limits but may be very common just a few hundred miles away. Only one state-listed rare species is known to occur on my property, Lobaria querzicans, but there may be others especially among the obscure crustose forms. The majority of lichens identified on my property are common or frequent in the state and the Western Great Lakes Region.
A few of the lichens found grow in very old forests and old-growth forests. These include Heterodermia speciosa, Lobaria pulmonaria, L. querzicans, Myelochroa auralenta, Pertusaria velata, and Punctelia appalachensis which have been found in forests on trees 60 or more years old. The growth of these lichens is slow and the trees on which I have found these species grow are all very old. Lobaria pulmonaria, for example, will take ten years from initial colonization as a propagule with its photobionts before it is large enough to produce the first apothecia (spore cups).
Most of my lichen searches have been made in forests but there is a large wetland area in the central part of the property that is vegetated by shrub willows and alders. These might be home to species not found in the forests and will be a focus of future searches. Other habitats to investigate are old concrete walls, soil on the roots of overturned trees, and the tops of trees (available only when they blow over). And I’m going to need to dust off my microscopes to get a better view of the crustose lichens.
Lichen Species (69)
Arthonia caesia, Arthonia radiata
Calicium (Mycocalicium) subtile, Calicium glaucellum
Cladonia cervicornis var. verticillata, Cladonia chlorophaea, Cladonia coniocrae, Cladonia cristalla, Cladonia gracilis ssp. turbinata, Cladonia ochrochlora
Lecanora allophana, Lecanora symmitica, Lecanora thysanophora
Lepraria caesioalba, Lepraria lobificans
Lobaria pulmonaria, Lobaria quercizans
Myelochroa auralenta, Myelochroa galbina
Ochrolechia arborea, Ochrolechia trochophora
Opegrapha (Alyxoria) varia
Parmelia flaventior, Parmelia sulcata
Pertusaria macounii, Pertusaria ophthalomiza, Pertusaria velata
Phaeophyscia ciliata, Phaeophyscia hirtella, Phaeophyscia pusilloides, Phaeophyscia rubropulchra
Physcia adscendens, Physcia aipolia, Physcia millegrana, Physcia subtilis
Physconia detersa, Physconia enteroxantha
Punctelia appalachensis, Punctelia rudecta
Ramalina americana, Ramalina roesleri, Ramalina sinensis
Tuckermannopsis (Cetraria) americana
Xanthoria fallax, Xanthoria polycarpa, Xanthoria ulophyllodes
Some helpful resources
The Ways of Enlichenment
Consortium of North American Lichen Herbaria (CNALH)