KEYS TO THE LICHENS OF MINNESOTA Prepared by Clifford Wetmore Dept. of Plant Biology University of Minnesota St. Paul, Minnesota 1981 Revised 1985 Revised 1988 Revised 1998 Revised 2000 Revised 2005 INTRODUCTION In preparation for a manual on the lichens of Minnesota numerous new collections have been made in many parts of the state and most of Fink's Minnesota collections have been re- studied. There are about 35,000 Minnesota collections in the herbarium and the lichen flora has increased to over 700 species. These preliminary keys have been prepared as an aid to further work on this flora and also for the use of students studying lichens in this area. The task of identifying the Minnesota lichens and preparation of the keys has been greatly facilitated by the work of Richard Harris and his keys to the Lichens of the Straits Counties, Michigan. The Minnesota keys are mostly new with the exceptions of the key to genera, key to the pyrenolichens and key to Bacidia which are only somewhat modified from those of Harris. However, all of these keys make use of some of the information in the Michigan keys by Harris and his contribution is gratefully acknowledged. The generic concepts are generally not as narrow as those of some workers but reference is usually made to the placement in the smaller genera. However, generic limits are changing so rapidly it is almost impossible to keep up. A few species not yet found in Minnesota but likely to be found are included but enclosed in parentheses. The 1998 revision adds some genera not included before, updates the nomenclature, cor- rects typographical errors and reformats the keys. These keys are still arranged according to the old spore-based genera because many of the characters used to distinguish the newer small genera are difficult (ascus tips, HPLC, etc.). In most cases the smaller genera also have their own keys. A few of the old synonyms are also indicated until we learn what the new names are. The 2005 revision adds a few keys and corrects some keys, nomenclature and errors. Some of the recently reported species are not in the keys but are listed at the end before the index. Clifford Wetmore 2 GENERA KEYS TO LICHEN GENERA Thallus fruticose Key I page 3 Thallus foliose Key II page 4 Thallus squamulose Key III page 7 Thallus crustose Key IV page 8 Key I. THALLUS FRUTICOSE 1. Thallus yellow or orange, K+ purple (parietin) ------------------- Teloschistes chrysophthalmus 1. Thallus some other color, not K+ purple ------------------------------------------------------------ 2 2. Algae blue green ---------------------------------------------------------------------------------------- 3 2. Algae green ---------------------------------------------------------------------------------------------- 4 3. Thallus much branched and ascending ---------------------------- Dendriscocaulon intricatulum 3. Thallus prostrate, filamentous ------------------------------------------------------------------ Ephebe 4. Thallus or podetia erect; growing on soil, wood, rock and bases of trees ---------------------- 5 4. Thallus pendulous or decumbent; growing mainly on trunks and branches of trees, rarely on soil or rock ---------------------------------------------------------------------------------------------- 9 5. Primary thallus squamulose or lacking; podetia hollow ------------------------------------------- 6 5. Primary thallus crustose, strap-like or absent ------------------------------------------------------- 7 6. Primary thallus squamulose; podetia corticate, usually not much branched (if intricatley branched, then podetia squamulose) ------------------------------------------------------- Cladonia 6. Primary thallus absent; podetia not corticate (surface arachnoid), intricately branched, never squamulose ------------------------------------------------------------------------ Cladonia (Cladina) 7. Thallus strap-like, flattened, channelled and involute, with marginal cilia, dark brown and pseudocyphellate ------------------------------------------------------------------------------- Cetraria 7. Pseudopodetia cylindrical, with or without cephalodia and phyllocladia ------------------------ 8 8. Pseudopodetia simple, with terminal pink apothecia; cephalodia and phyllocladia absent; apothecia pinkish and on short stalks -------------------------------------------- Baeomyces rufus 8. Pseudopodetia mostly branched, sometimes tomentose; cephalodia and phyllocladia present; apothecia terminal, lateral or absent -------------------------------------------------- Stereocaulon 3 GENERA 9. Thallus filamentous, terete --------------------------------------------------------------------------- 10 9. Thallus flattened or angular -------------------------------------------------------------------------- 12 10. Filaments with a cartilaginous central strand ------------------------------------------------ Usnea 10. Filaments lacking a cartilaginous central strand ------------------------------------------------- 11 11. Thallus pale yellow green (usnic); tips of branches usually ending in distinctive hook-shaped isidioid soredia; divaricatic acid present --------------------------------------- Ramalina thrausta 11. Thallus gray, brown or almost black; tips of branches without isidioid soredia ------- Bryoria 12. Medulla C+ red (lecanoric acid); thallus isidiate, pale gray; usually on conifers --------------- - ------------------------------------------------------------------------------------ Pseudevernia consocians 12. Medulla C- or if C+, not isidiate ------------------------------------------------------------------- 13 13. Thallus stiff with interwoven internal cartilaginous strands, pale yellow green (usnic acid), eciliate; lower side corticate ---------------------------------------------------------------- Ramalina 13. Thallus not stiff, lacking internal cartilaginous strands -----------------------------------------14 14. Margins of thallus eciliate; lower side corticate --------------------------- Evernia mesomorpha 14. Margins of thallus ciliate; lower side decorticate ------------------------------------------------ 15 15. Medulla K- ------------------------------------------------------------------------ Anaptychia setifera 15. Medulla K+ red (salazinic acid) ------------------------------------------------------ Heterodermia Key II. THALLUS FOLIOSE 1. Thallus attached to the substrate at a single point near the middle of the thallus (umbilicate) - 2 1. Thallus attached at more than one point -------------------------------------------------------------- 6 2. Algae blue-green; on rocks ----------------------------------------------------------------------------- 3 2. Algae green ----------------------------------------------------------------------------------------------- 4 3. Thallus black; no obvious ascocarps -------------------------------------------------------- Lichinella 3. Thallus reddish brown; with numerous immersed ascocarps ----------- Phylliscum demangeonii 4. Thallus with embedded perithecia or, if lacking perithecia, then with obvious immersed flask- shaped pycnidia, thallus usually pale ---------------------------------------------------- Dermatocarpon 4. Thallus with rounded to angular apothecia or often sterile; pycnidia not obvious --------------- 5 5. Thallus green, apothecia lecanorine -------------------------------------------------------- Rhizoplaca 5. Thallus usually dark colored although pruinose forms appear paler; apothecia lecideoid -------- -------------------------------------------------------------------------------------- Umbilicaria sens. lat. 6. Thallus bright yellow or orange due to pulvinic acid derivatives or anthraquinones ------------ 7 6. Thallus some other color, at most pale yellowish due to usnic acid ------------------------------- 9 4 GENERA 7. Thallus K+ purple (parietin) ------------------------------------------------------------------ Xanthoria 7. Thallus K- ------------------------------------------------------------------------------------------------- 8 8. Pigments mainly in cortex; lobes narrow, 1-3 mm across ------------------------------ Candelaria 8. Pigments mainly in the medulla; lobes broader ---------------------------------- Cetraria sens. lat. 9. Phycobiont a green alga ------------------------------------------------------------------------------- 10 9. Phycobiont a blue-green alga; thallus usually dark colored, bluish, brownish or blackish, often gelatinous when wet; algal layer distinctly bluish in section ------------------------------------ 23 10. Thallus inflated, hollow ------------------------------------------------------------------------------ 11 10. Thallus not inflated, solid ---------------------------------------------------------------------------- 12 11. Lobes with large pores in the upper surface opening into the hollow interior; soralia laminal, usually initiated around a pore; atranorin, stictic and constictic acids -- Menegazzia terebrata 11. Lobes without pores on upper surface; soralia terminal or subterminal ----------- Hypogymnia 12. Lower surface lacking cortex ----------------------------------------------------------------------- 13 12. Lower surface corticate ------------------------------------------------------------------------------ 16 13. Lobes very broad; thallus bright green when wet, with black scale-like cephalodia on the upper or lower surface ----------------------------------------------------------------------- Peltigera 13. Lobes narrow; thallus not bright green when wet, lacking