Morel Mushrooms, Macrofungi, Corticolous Myxomycetes, And American Elm Trees Harold W. Keller Botanical Research Institute of Texas, 1700 University Drive, Fort Worth, TX 76107-3400; [email protected]

Abstract: the University of Iowa. American elm structure and external slime sheaths. cultures recently led to the discovery Ulmus americana (American elm) Key Words: of new species of Mycena, corticioid occurs in Texas and mostly has escaped Licea species, moist chamber bark crust fungi represented by species of the pathogenic fungus Ophiostoma ulmi cultures, Morchella species, Ophiostoma Dendrothele, and myxomycete life cycle ulmi, slime molds, Ulmus americana. and O. novo-ulmi, the causative agents stages. Many corticolous myxomycete of Dutch elm disease. The American species in the genus Licea are small in Introduction elm is a beautiful ornamental shade the 100–200 µm range, easily overlooked The demise of American elm trees tree that was planted in cities and in moist chamber bark cultures from begins in my hometown Peabody, towns throughout the Midwest as a living trees, and often are species new Kansas in the 1950s, and continued monoculture, facilitating the spread to science, for example, Licea iridescens into the 1960s and 70s at the University of Dutch elm disease by the elm bark recently described. Photographic of Iowa. Although the pathogen for beetle insect vector and by root grafts. images of rare and undescribed tiny Dutch elm disease had been around The association between dying elm trees myxomycete species are shown using long before then, the devastation and and morel mushrooms is described from multi-focus imaging and computerized removal of American elm trees was Texas to Iowa and Ohio. Described here stacking giving greater depth of field visually most dramatic in Iowa City is the early history of moist chamber and three-dimensional detail. The when I was a Ph.D. student studying cultures using American elm tree importance of myxomycete stalks is myxomycetes with Professor George trunk bark collected in the 1930s at discussed especially in regard to internal W. Martin at the University of Iowa.

Fig. 1. Photo by Harold W. Keller. Dead American elm trees with V-shaped branching pattern.

Spring 2021 FUNGI Volume 14:2 23 merican elm were widely seen myxomycetes were abundant, especially footed morel” (Morchella "crassipes") on the campus and lined the Perichaena chrysosperma, P. depressa, was found (12–14 inches in height with a streets in Iowa City. More and Licea biforis on the underside of the stalk 5 inches in length and 2.4 inches in Athan 2,000 American elms once grew bark separating from the woody tree width). This “species” is now considered on the University of Iowa campus trunk. This was a massive fruiting of simply an older developmental phase of but were eventually ravaged by the Licea biforis represented by thousands M. americana and not a distinct species Dutch elm fungal pathogen so that of date-shaped, orangish sporangia with (Keller, 1998). only two survived. Apparently one their distinctive longitudinal slit-like Morels assigned to Morchella tree that survived was located on the dehiscence and bright yellow spore americana have been found by David campus Pentacrest. It was a towering mass. (Fig. 2). Lewis, March 12, 2005 in Edwards giant estimated to be about 15 feet in County near Barksdale as part of the circumference, 93 feet in height, and American elms famous Edwards Plateau and Hill supposedly planted in the 1880s, and and morel mushrooms Country of Texas. This is rugged terrain recognized as a state champion tree Morel hunters in Iowa, Kansas, of small ravines and canyons with (Snee, 2012). Missouri, and Nebraska (especially in scattered mixed juniper-oak woods. Another site farther north at Lake Fig. 2. Photo by Edward D. Forrester. Licea biforis sessile sporangia. Whitney in Bosque County abundant Morchella americana fruit bodies were collected on March 24, 2001 in oak-juniper woods. March is the best collecting time in South-Central to North Texas for morel mushrooms. Midwestern morel collection sites are productive in early March beginning in Texas and continuing northward until early June in northern Minnesota. April and May are the prime times to collect morels in Kansas, Missouri, Iowa, and Ohio, states where I (HWK) have collected morels. Collection times depend upon adequate soil moisture with temperatures between 50–55F and when day and night-time temperatures vary between 55–70F. This usually means about the time red bud trees (Cercis canadensis) and lilac shrubs (Syringa American elm were most often the river bottoms of western Missouri vulgaris) start to bloom and ground planted as a monoculture close together and surrounding bluffs of eastern plants like mayapples (Podophyllum as they lined both street sides in Iowa Kansas) will find helpful tips for where peltatum) cover the forest floor. The City. The mycology laboratory in the and when to locate and how to collect tree canopy is more open with sunlight Department of Botany at University morel mushrooms in Thompson (1994). reaching ground sites because the of Iowa was the testing center for Morels are early spring mushrooms in deciduous trees have not yet leafed out. isolating and confirming infections of Texas and occur from early March in the Warmer earlier spring temperatures may Ophiostoma ulmi for American elm Hill Country around Austin northward also mean earlier morel mushrooms. in Iowa City (1967–1971). When one to the Dallas-Fort Worth area. In Texas, Old abandoned apple orchards (Malus tree became infected with O. ulmi cedar groves of mostly mountain cedar sp.) with some dying trees are also (then referred to as Ceratiocystis ulmi), (Juniperus ashei), and less often eastern productive sites for morels. However, the all nearby trees also became infected red cedar (Juniperus virginiana), occur spectacular “bushels of fruiting bodies” through root grafts, so that every tree in areas that yield productive fruiting of Morchella americana that appear on the block had to be cut down. bodies of the “yellow morel” (Morchella in season around dying American elm A group of dead elm trees was found americana), formerly called M. esculenta trees were the best habitats according to near Hawkeye Drive Apartments where (see Bunyard, 2013, for discussion of Thompson (1994). married students and our family lived name changes). An interesting report In the 1950s and 1960s American elm on the outskirts of Iowa City. These of morels (Morchella americana) was trees were dying by the thousands of dead trees were still standing; their described for the first time at River Dutch elm disease in cities and towns outer layers of bark were separating Legacy Parks in Arlington, Texas, March throughout the Midwestern states and from the wood or had already fallen 21, 1998, growing near a cedar elm this created ideal habitats for morel to the ground (Fig. 1). Morels were (Ulmus crassifolia). A few days later mushroom hunters who flocked to their never observed around these trees but in the same location, the giant “thick- favorite sites to find morels. However, as 24 FUNGI Volume 14:2 Spring 2021 Fig. 3. Photo by W. May. Dying Fig. 4. Photo by Walt Sturgeon, Morchella americana near dead American elm tree. American elm tree, May 4, 2015, Columbiana County, Ohio.

Thompson notes, American elms were most productive in the first year of dying and even the second year after they died, but once the bark had sloughed off, the morels no longer were found (Fig. 3). Thompson (1994) describes collecting 1,500 pounds a day in the 1970s. Unfortunately, stands of American elm today are hard to find, although scattered trees in some areas are still productive. Thompson’s continuous field observations of the changing color phases of grey to yellow Morchella americana suggested these were color phases of the same species that was later confirmed by genomic studies (Fig. 4). Fewer American elms resulted in also locating dying cottonwood trees and stumps as another source of morels. Thompson was often collecting in state Fig. 5. Photo by W. May, holding boxes of morels in prime condition. parks, and at that time it was legal, but today in many areas it is illegal, so make sure you follow state and federal laws. Willie May (WM) from Missouri has been collecting morel mushrooms since 1991 (Fig. 5). Every spring in the months of April and May he forays in Missouri, Illinois, Iowa and Wisconsin, with his first priority spotting groves of dying elms. Healthy live American elm trees are not usually the best source of morel mushrooms. Indeed, if the tree begins dying in the fall, usually the next spring morels are not found. Typically, American elm trees should be completely dead before morels Spring 2021 FUNGI Volume 14:2 25 cultures. Some field trips were made to the American elm tree site following rainy periods and cloudy weather of several days but mycelium or basidiomes were not observed. This suggests that the discovery of fleshy macrofungi on the trunk bark of living trees may be a potential source of hidden biodiversity given the use of moist chamber cultures. Another example of macrofungi on living healthy trees is the genus Dendrothele referred to commonly as white crust corticioid fungi. An on- going study of these fungi in nature parks, Fort Worth residential areas, at the Botanical Research Institute of Texas, Fort Worth Botanic Garden in Fort Worth and in River Legacy Park, Fig. 6. Photo by W. May. Morchella americana at base of live white ash tree. Arlington, Texas, Tarrant County, has yielded more than 100 collections of mostly Dendrothele jacobi on American are induced to develop and then are fungi (and slime molds), why not try to elms (27 trees) and cedar elms (32 limited to only a couple of years (WM, culture them indoors. Just bring in some trees) (Bordelon et al., 2020). Cedar personal observation). bark from live trees, set up in a moist elms predominate on the eastern side The two best tree species in the chamber, and watch for fruitings. of the BRIT campus near University Midwest associated with morel Drive (15 trees) with Dendrothele jacobi. mushroom occurrences are American Previous studies on tree canopy Healthy Juniperus virginiana (eastern elms, Ulmus americana, (probably the corticolous macrofungi red cedar) predominate (17 trees) at most productive and most frequent Macrofungi are known to fruit Tandy Hills Natural Area in Fort Worth source of morels) and white ash, from the bark of many kinds of trees. with Dendrothele nivosa specifically Fraxinus americana, (probably the Previously, three fleshy macrofungi associated with these trees (Fig. 7). second best tree, Fig. 6) and other represented by Lentaria byssiseda, species in both genera of these trees. Mycetinis opacus, and Mycena supina Ash trees are dying by the millions from were found on the trunk bark or lateral emerald ash borer beetle, however, branches of living trees in the Great dying or dead ash trees apparently do Smoky Mountains National Park (GSMNP) (Keller, 2004; Keller et al., not create morel mushroom collecting 2009). More than 500 individual trees opportunities. Unfortunately, the fate that included 52 taxa were climbed using of ash trees appears similar to that the double rope climbing method and of American elms with massive tree sampled for myxomycetes and macrofungi die-offs except in isolated habitats. (Kilgore et al., 2008). This occurred each Fig. 7. Photo by Robert J. O’Kennon. Some habitats may not have these tree summer over an eight-year-period (2000– species so look for alternative tree 2008). The basidiomycete macrofungi species such as tulip tree (Liriodendron observed and collected certainly was a Cortoicolous myxomycetes and tulipifera); cottonwoods (Populus scanty harvest from large healthy living American elm trees spp.), oaks (Quercus spp.), sycamores trees in a temperate and old growth Gilbert and Martin (1933) generally (Platanus occidentalis), black locusts deciduous forest. are given credit for introducing the (Robinia pseudoacacia), black cherry Fleshy macrofungi appear to be rare moist chamber culture technique (Prunus serotina), among others. on tree trunks and in the upper canopy using bark from living trees. Many Although these aforementioned morel (Keller et al., 2009). In addition, the tiny myxomycete fruiting bodies were collecting sites more frequently are the recent discovery of a novel species discovered on wetted bark samples in sources of morels, they also may appear Mycena ulmi from an American elm glass Petri dishes taken from different unpredictably in unexpected places tree in the Fort Worth Botanic Garden living tree species, including American (Hemmes and Stallman, 2020). is another example of an apparent elm, referred to as “elm” in their paper. Morel mushrooms are not the only cryptic hidden species (Perry et al., Gilbert was a student of G. W. Martin fungi associated with elm trees. This 2020). At least six field trips failed to working in the Mycology Laboratory spring be on the lookout for other detect any basidiomes of Mycena ulmi at the University of Iowa (Keller, 2012). macrofungi—some fruiting directly on the trunk bark surface but moist Moist chamber bark cultures from living from the bark of elms. And if you want chamber cultures yielded 12 collections trees yielded 30 myxomycete species; to better your chances at seeing some all developed in tree bark moist chamber however, in some cases, the source of the 26 FUNGI Volume 14:2 Spring 2021 tree species was not given (Gilbert and Martin, 1933). Noteworthy observations Order Echinosteliales Clastoderma debaryanum var. emperatorium+, included the fast-forming fruiting C. microcarpum*, Echinostelium arboreum+, E. bodies, some on the second or third day coelocephalum+, E. minutum+ after wetting and others after five or six days. Myxomycete species cultivated Order Liceales Cribraria minutissima+, C. violacea+, Licea from elm bark were Comatricha laxa, biforis*+, L. denudescens*+, L. inconspicua*, L. C. fimbriata, Enerthenema papillatum, iridescens+, L. kleistobolus*+, L. marginata*, L. Clastoderma debaryanum var. nannengae+, L. parasitica*+, L. pedicellata+, L. emperitorium, Cribraria minutissima, perexigua+, L. scyphoides*+, L. a spiny-spored C. violacea, Licea biforis, L. tenera, undescribed new species+; L. an orange- Hymenobolina parasitica (currently as operculate new species+ Licea), Margarita metallica (currently as Calomyxa), Ophiotheca wrightii Order Physarales Badhamia affinis*, Badhamiopsis ainoae*+, (currently as Perichaena chrysosperma), Diderma chondrioderma*, D. corrugatum*, Arcyria cinerea, and Hemitrichia Didymium clavus*+, D. orthonemata*, minor. Echinostelium minutum is Physarum crateriforme*+, Trabrooksia listed as common on frondose and applanata* coniferous trees but no specific tree was named. These species are considered Order Stemonitales Comatricha fimbriata+, C. laxa*+, Enerthenema corticolous myxomycetes that develop, papillatum+, Macbrideola cornea+, M. grow and form fruiting bodies on decapillata+, M. martinii+, M. scintillans+ the bark surface of living trees and woody vines (Keller and Braun, 1969; Order Trichiales Arcyria cinerea*+, Calomyxa metallica*+, Everhart and Keller, 2008; Keller et al., Dianema (clustered spores) +, Minakatella 2008; Keller et.al., 2009). Most of these longifila*, Perichaena chrysosperma*+, P. corticolous myxomycetes have been depressa*+, P. minor+, 42 total species collected in the field on bark of living trees especially Juniperus virginiana TABLE 1. Myxomycete species list from American elm trees (taxa arranged and Ulmus americana (Keller and alphabetically by genus and species). Corticolous myxomycete species listed from Braun, 1999; Keller et.al, 2009); Parker multiple living American elm trees based on field collections (*) and moist chamber and Keller, 2003). bark cultures (+) arranged by taxonomic orders and alphabetically by genus The majority of myxomycete fruiting and species (Gilbert and Martin, 1933; Gilbert, 1934; Martin and Alexopoulos, bodies develop along the bark edges “edge 1969; Keller and Braun, 1999; and HWK collection books). These collections were effect” and in deeper crevices and pockets compiled over a period of about 70 years, and along with those from eastern where these areas stay wetter longer and red cedar, represent the two species of trees where the majority of corticolous dry out more slowly than on the bark myxomycete species occur (Keller et al., 2009). surface. Corticolous myxomycete species ferns, fungi, lichens, liverworts, mosses, associated with morels. American elms diversity appears highest in rank order: myxobacteria, and tardigrades, on the also had approximately 42 species of eastern red cedar, American elm, and red trunk bark of living trees and woody corticolous myxomycetes (see Table 1) maple (Acer rubrum). vines high in the tree canopy in GSMNP and ranked in the top four tree species. In another paper, Gilbert (1934) (Snell and Keller, 2003; Snell et al., 2003; Many of the smaller myxomycete species described three corticolous myxomycete Keller et al., 2003, Davison and Keller, in the genera Echinostelium and Licea species new to science: Macbrideola 2004; Keller, 2004; Keller et al., 2004; are found on the trunk bark of living scintillans and M. decapillata Keller, 2005; Keller, et al., 2009; Kilgore trees (Keller and Brooks, 1976; Keller (Macbrideola is a commemorative et al., 2008; Keller and Barfield, 2017). and Brooks, 1977; Keller and Braun, generic name for Thomas H. Macbride, Elm trees were not included in these tree 1999; Marshall and Keller, 2018; Keller a world famous myxomycetologist and canopy studies because they were not and Marshall, 2019). former President of the University of present in sufficient numbers and size. Iowa) and Hymenobolina pedicellata Canopy corticolous myxomycete Methodology (currently in the genus Licea). All three species diversity on living trees usually Field collections and sampling of species form tiny plasmodia, each followed a higher pH pattern nearer Ulmus americana trees producing one tiny stalked sporangium 7.0 to a lower pH of 4.0 and were rank American elm trees selected for this on tree trunk bark of living trees. ordered by number of species as follows: study were the largest at each of the eastern red cedar 50, red maple 49, white Corticolous myxomycete species study sites; minimum trunk diameter oak 41, tulip tree 39, white ash 31, white diversity on bark of living trees of 60 cm at dbh, diameter at breast pine 24 (Snell and Keller, 2003; Keller, A series of papers documented the height=1.5 meters) and total height (18 2004; Keller et al., 2009). These same occurrence of myxomycete fruiting to 30 meters). Nine American elm trees tree species coincidentally also may be bodies and other life forms, including were sampled at Oliver Nature Park, Spring 2021 FUNGI Volume 14:2 27 two at the Fort Worth Botanic Garden, while remaining at room temperature a standard collecting box 4.5 x 10.5 x and five at the Fort Worth Nature at approximately 22–25C. On day two 2 cm. Labels included species name. Center and Refuge for a total of 16 trees. and day six after wetting and every two state, county, collection locality, habitat, Dendrothele specimens were made on to four days thereafter for four weeks UTM coordinates, bark collection date, giant American elm trees in residential the plates were examined under a Nikon wet date, harvest date, collector’s name areas of Fort Worth, from area nature dissecting microscope with a MKII Fiber (legit) and accession number, person parks, and the FWBG campus. Optic light source at magnifications of identifier (fide) were affixed to the box A heavy bladed knife was used to pry 50x to 150x. Each dish was examined top. A Nikon Alphaphot light compound tree bark samples avoiding any damage systematically from side to side after microscope was used to examine to underlying tissues. Pieces of bark were the lid was removed to ensure that each slides and make measurements using collected from all sides of the trunk at piece of bark was examined. However, a calibrated ocular reticule to identify approximately 1.5 to 1.8 meters until removing the lid was minimized to avoid myxomycete species. enough samples per tree were gathered to exposure due to aerial contamination, Microscope glass slides (75 mm x half-fill a paper bag (ca 1000 cm3). Every especially by Trichoderma, a commonly 25 mm x 1 mm thick) with a frosted bag was labeled with the identifying tree encountered green mold. end were used to make mounts number, collection date, and site location. of myxomycete structures for Most bark samples were collected Location and preservation of identification. Small pins attached to during the summer months of June, July, myxomycete fruiting bodies wooden handles were used to remove and August and were placed in moist Moist chamber cultures of tree bark fruiting bodies from the bark. A droplet chamber cultures within two weeks. Field often have tiny scattered sporangia of of clear lactophenol was placed in the collections of Dendrothele were made Echinostelium and Licea species (less center of the microscope slide, sporangia throughout the year whenever weather than 0.1 mm). Their size and scattered were added, and a square cover slip conditions permitted. habit make it difficult to find these (22 x 22 mm and 0.16 mm thick) was sporangia, therefore to save time, insect gradually lowered at an inclined angle Moist chamber bark cultures pins (size 1 with nylon head stainless over the specimen to avoid creating air Moist chamber culture preparation steel needle, 40 mm long and 0.35 in bubbles. Permanent slides were made techniques were described in part diameter) and (silver flat-head 1-inch for future use by sealing the edge of the previously (Keller et al., 2008; Keller and needles) were used to pin point fruiting cover slip with ZUT a resiniferous slide- Marshall, 2019; Kilgore et al., 2009; Perry body locations. When moist chambers ringing compound. Identification labels et al., 2020; Scarborough et al., 2009). were re-examined pins facilitate making were written in lead pencil on the frosted Consult other articles that describe microscope slides for identifications. end of the slide covered with clear tape inexpensive ways to prepare moist However, these pins may become to prevent future smudging. Slides were chamber tree bark cultures (Keller et dislodged when preparing permanent wrapped with lens paper and placed in al., 2008). This study followed a moist collections and type specimens on dried properly labeled collection boxes. chamber culture protocol described tree bark glued in boxes. Pins also may herein. Two moist chamber cultures per interfere with photographic techniques Photography using light and tree were prepared using the American and must be removed when orienting scanning electron microscopes elm trunk bark samples to document the the specimen under the microscope. An Olympus BH2 microscope with corticolous myxomycetes present. Each The presence of myxomycete fruiting EPI Illumination and ultra-long working sterile, plastic Petri dish (150 x 25 mm) bodies on dried tree bark were pin- distance objectives of 5X, 10X and 20X was lined with one sterilized P8-creped pointed using a white paint permanent in combination with 10X eyepieces filter paper fitted to cover the bottom. waterproof liquid opaque marker with was used to observe myxomycete Bark samples were randomly selected an extra fine (0.7 mm) tip. A white dot sporangia. Photographic images were from a paper bag and placed in the Petri was placed equidistant on either side made with a Sony A6000 and a NFK dish bark outer-side up so that the bark of the fruiting body and close enough 2.5X relay lens at 10 mega-pixel settings. pieces were close, but not overlapping in a straight line so that both the white Multiple image focal stacking was or touching. Each Petri dish was labeled dots and specimen are in the field of used for both microscopic slides and with the tree number, collection site, view simultaneously. This technique habit photographs. Each image stack and date wetted on the lid and bottom should prove valuable in marking the varied between 10 to 75 individual side. 30 mL of pH 7 deionized sterile location of myxomycete fruiting bodies images merged using Helicon Focus water was added around the bark to in type collections especially when their software version 6.8.0. Image stacking ensure thorough and even wetting. presence is obscured by look-alike life increased depth of field so that the entire After 24 hours any excess water was forms. All observations of plasmodia and sporangium (stalk and spore case) were decanted. Cultures were placed near fruiting bodies of date and time were in sharp focus. Images were optimized a window exposed to indirect natural recorded in a notebook. Identifications using Adobe Photoshop CC 19.0. light and ambient room light and were made using dichotomous keys and SEM specimens were mounted on remained in the same spot unless they illustrations in Martin and Alexopoulos 12.5 mm stubs with conductive tape by were being examined under a dissecting (1969). Pieces of dried bark with fruiting excising one of the sporangia including microscope. Incubation occurred with bodies of myxomycete sporangia were a small amount of the substrate then light and dark cycles of June to July removed and glued to the bottom of mounted on a piece of double stick 28 FUNGI Volume 14:2 Spring 2021 facility at BRIT includes a Hitachi sporangium of Macbrideola declinata SU 3500 high resolution SEM which illustrates the structural parts when was used to observe and photograph it was described as a species new to specimens. Images were recorded in a science by Brooks and Keller (Eliasson reduced contrast mode and processed et al., 1988). The ornamentation and in Photoshop to retain highlight color of the spores, provides additional information and extract the maximum morphological characters, sometimes detail available. only seen with the higher magnification 1,000x under oil immersion objective of Importance of myxomycete a light microscope or with the scanning fruiting bodies electron microscope. More information concerning the Moreover, one example of missing importance of myxomycete fruiting morphological characters in myxomycete bodies can be found in Keller and species descriptions is the presence of Everhart (2010). This article published in an external stalk sheath (Figs. 9a and Fig. 8. Photo by Harold W. Keller, FUNGI labels by Courtney M. Kilgore. has been cited 2,933 times from 9b) and internal presence or absence June 2016–March 2021 as posted on the of stalk fibers. These morphological tape which is attached to a small (1x2”) Univ. of Nebraska Digital Commons. stalk characters are helpful when card stock. The card was inverted The morphological characters used in assigning taxa to genera such as and the sporangia pressed to the top, monograph species descriptions and Comatricha, Lamproderma (Meriderma), tapped, removed and the procedure keys to identify myxomycete species Macbrideola, and Stemonitis. Comatricha repeated until the desired amount of the are associated with the fruiting bodies and Lamproderma have fibrous stalks specimen had adhered to the stub. A (Martin and Alexopoulos, 1969). The characterized by an interlaced network of small paint brush was used to distribute presence or absence of a peridium, mostly dark fibers as inComatricha laxa spores across the stub adhesive surface. capillitium, surface net, columella, when transmitted light passes through The stub was coated with gold using calcareous structures, and stalks serve to the stalk (Fig. 9c) and when the stalk is a Hummer VII sputtering machine to distinguish the orders, families, genera, embedded, sectioned, and stained with a thickness of 3 nm. A new genomics and species (Fig. 8). This labeled stalked methylene blue (Fig. 9d). These fibers

Spring 2021 FUNGI Volume 14:2 29 Fig. 9a. Photo by Edward D. Forrester. Comatricha species with slime sheath at base.

Fig. 9c. Comatricha laxa, note Fig. 9f. Cross section of Stemonitis internal strands of fibers. hollow stalk (center) stained with methylene blue.

Fig. 9d. Comatricha laxa, note upper portion of sporangium Fig. 9g. Macbrideola scintillans. Fig. 9b. Photo by Edward D. with spores and stalk fibers Forrester. Lamproderma sauteri stained blue. stalked sporangium with plasmodial slime sheath at base. are sometimes difficult to see because the stalk is too opaque and impossible to discern their presence. However, if the stalk is broken near the base the fibers can be seen often protruding at the break as in figure forLamproderma cribrarioides (Fig. 9e). Stemonitis species Fig. 10. Photo by Edward D. have stalks that are hollow (Fig. 9f). One Forrester. Echinostelium arboreum note: the preferred term used here for stalked sporangium. myxomycete fruiting bodies is stalk and Fig. 9e. Photo by Edward D. Forrester. or forms) is about 1,100 species mainly the preferred term for fleshy fungi is stipe. Lamproderma cribrarioides broken because the figure has grown in recent Observations of selected stalk at base with protruding fibers years. The actual number varies between corticolous myxomycetes, and sheath along edge. 1060–1095 as some species are under review due to their validity. arranged alphabetically by information system of Eumycetozoa Echinostelium arboreum is a rare genus and species (myxomycetes). The most recent data corticolous myxomycete that represents Carlos Lado (2021) maintains a for myxomycete taxa is as follows: a new record for the state of Texas running updated total of myxomycete the number of accepted species of (Fig. 10). Currently there are 18 valid taxa as part of an online nomenclatural myxomycetes (not subspecies, varieties Echinostelium species recorded by Lado 30 FUNGI Volume 14:2 Spring 2021 Fig. 12. Photo by Edward D. Forrester. Licea iridescens sessile sporangium with iridescent sides and apical debris.

Fig. 11. Photo by Edward D Forrester. Undescribed species of Licea with recessed lid and raised margins (operculum).

(2021), however, E. arboreum is the only morphological details of this species are americana and Malus apple trees (Keller species with a persistent shiny peridium. illustrated by Moreno et al. (2001). This & Braun, 1999). The sessile sporangia or Although the stalked sporangia are species was found multiple times on short plasmodiocarps have a longitudinal small (100–120 μm total height, 40–50 Ulmus americana trunk bark in moist slit that opens like a clam exposing the μm in diameter) the combination chamber cultures at Oliver Nature Park bright yellow spore mass as in Fig. 2. The of a shiny persistent peridium and in Mansfield, Tarrant County. fruiting bodies are often present in great golden color facilitate locating and Licea biforis is a common species numbers which facilitates location and identifying this species with a dissecting with a distinctive fusiform or date shape easy identification. Although the color is microscope (Keller and Brooks, 1976). found on the trunk bark of living or variable, the orangish color shown here SEM photographic images that show standing dead trees especially Ulmus is more typical.

Spring 2021 FUNGI Volume 14:2 31 spores (Fig. 15). Fig. 15. Photo by This cone-shaped Edward D. Forrester. mass develops first Immature stage of Licea before the spores pseudoconica sessile form. In addition, sporangium. the spores appear to develop first in the apical region. The mature spore- filled sporangial body proper is more Fig. 13. Photo by spherical. These Edward D. Forrester. Crystals with moist chamber trunk yellow bands. bark collections of Licea pseduoconica on Ulmus americana represent new records for the state of Texas. possible to observe this species in Licea perexigua is a small sesssile to Fig. 14. Photo the field with a 20X widefield hand short stalked corticolous myxomycete lens. because of the larger size (total which is more difficult to identify by Edward height 200–500 μm and 75–175 μm in because the spherical sporangium D. Forrester. diameter). Species descriptions vary (40–110 μm in diameter) resembles Stalked with reference to the peridium and other objects on the tree bark surface. sporangium of dehiscence patterns. The photograph This species is a new record for the state Licea pedicellata with crystal shown here fits the species description in of Texas. adhering near base. Keller and Braun 1999: “… the spore case Licea undescribed new species. This often dries and the wrinkled peridial rare taxon was found at Oliver Nature surface gives the appearance of plates Park, Tarrant County, Texas on the trunk Licea iridescens is a species recently and sutures.” This photograph (Fig. 14) bark surface of a living Ulmus americana new to science that developed in moist shows a smooth peridial outer surface, tree in moist chamber cultures (Keller chamber cultures with spectacular a furrowed stalk typical of most fresh and Marshall 2019). The genusLicea iridescent sporangia often associated mature specimens in moist chambers, has about 75 valid species (Lado, 2021). with crystals of unknown origin and and a crystal at the stalk base. Another This taxon has one morphological irregular shapes (Fig. 12) (Keller and study of stalked Liceas by Wrigley de character not found in any other Marshall, 2019). The sporangial sides Basanta and Lado (2005) has SEMs species of myxomycete: a transparent, sparkle with bluish, pinkish, and reddish of this species but unfortunately does single, thin, colorless, peridium colors when the peridium is highlighted not confirm everything in their species lacking ornamentation (Fig. 16). In by an external incident directed optical description “…dehiscence into irregular addition, the black spores have a type of light source illuminating the surface. A platelets 20–30 μm wide…” The dried ornamentation consisting of long spines dark apical patch of debris forms first in sporangia displayed with SEM do not and a spore wall of uniform thickness not early developmental stages. Crystal fields show this dehiscence pattern. found in any other species in the genus on the tree trunk bark cover the bark Licea pseudoconica is a distinctive and Licea (Fig. 17). The sessile sporangia are surface brightly shining with an optical diminutive species (70–120 μm in height difficult to detect and select because light source (Fig. 13). These crystals and 55–90 μm in diameter) that has a of their tiny size and their association vary in size, are irregular in shape, prominent whitish cone of gelatinous with Nostoc ball developmental stages and are often associated with Licea debris apically giving the general (a cyanophycean alga) that can be iridescens and apparently never have appearance of a snow-capped mountain. confused with sporangia. Light and SEM been described before in the published It was described as a species new to photographic images clearly highlight literature. These crystals were newly science by Keller and Brooks (1977) but these morphological characters. discovered on numerous American also discussed from collections made in Licea undescribed new species. elm trunk tree bark surfaces and are Florida (Keller 1973). Abundant sessile This taxon was rare with only a few part of an ongoing study to determine sporangia often occur along bark edges. sessile sporangia which were distinct their composition, origin, and function. This edge affect facilitates locating and because of the burnt orange color with Collections: holotype: BRIT 478988. identifying sporangia highlighting the a recessed operculum with raised edges Licea pedicellata has stalked black conical shape in profile. Developing early and a silvery surface. The circular lid sporangia that occur abundantly on the immature sporangial stages clearly show actually popped off on several sporangia trunk bark of living Ulmus americana the apical cone of debris as a transparent exposing the yellow spores underneath. and Juniperus virginiana trees. It is mass separate from the underlying More specimens are needed before this 32 FUNGI Volume 14:2 Spring 2021 Fig. 17. Photo by Billy G. Stone. SEM of spiny spores seen in Fig. 16.

Fig. 16. Photo by Edward D. Forrester. Undescribed Licea species with intact thin, membranous peridium surrounding black spores. taxon can be described as a species new the stalk is hollow. The thin peridium otherwise noted. SEMs presented in this to science (Fig. 11). remains as a conspicuous collar at the publication were generated with support Macbrideola cornea is common and juncture of the columella and stalk. from the George C. and Sue W. Sumner widely distributed wherever Ulmus Molecular and Structural Laboratory americana and Juniperus virginiana Epilogue at the Botanical Research Institute of trees are found, especially in the latter American elms are more than Texas. Bob O’Kennon assisted with the case, when these trees are planted in beautiful ornamental shade trees. Joyce collection of American elm bark. Vanessa cemeteries throughout the Midwest Kilmer’s poem "Trees" (1913) reminds Marshall prepared moist chamber bark and Southeast. This is a new record us how special a tree is in part because cultures, made permanent slides, and for Tarrant County, Texas. The stalked a nest of robins may live there. But boxed and labeled specimens. Edward sporangia (0.6–2.5 mm in total height American elm trees are far more than D. Forrester took LM photographs and and 0.12–0.3 mm in diameter) are ornamental objects, they are part of assisted with measurement of sporangia. widely scattered, usually solitary, with our human experience as well as many Billy G. Stone assisted with microscopic branching capillitial threads arising from other hidden life forms that live there. slide photography and SEM preparation the apex of the columella. Urban trees improve the streetscape in and photographs. Karen Nakasone Macbrideola scintillans is a new many ways including: visual appeal and identified all of theDendrothele record for Tarrant County, Texas brilliant autumn golden-yellow fall leaf specimens. The author thanks the but is apparently widely distributed colors for American elms; improve air University of Florida Graduate School for throughout the world. It appears quality by absorbing CO2, deplete ozone, a Postdoctoral Fellowship that supported widely scattered and usually solitary and reduce particulate matter and noise his research on myxomycete stalks. The in moist chamber trunk bark cultures abatement; provide shade from solar author thanks W. May and B. Bunyard appearing most frequently on Ulmus radiation lowering energy consumption for much valuable morel information and americana and Juniperus virginiana in residential areas; serve as home and tips. This paper is dedicated to Professor living trees in North America. A detailed shelter for wildlife including nesting Dr. Thomas W. Gaither, who was a Ph.D. species description, LMs, SEMs, and and roosting birds, squirrels, and other student with HWK at the University photographic illustrations highlight fauna; reduce storm water runoff and of Iowa and co-author of myxomycete this species in Eliasson et al. (1988). protection from wind; increase property publications, outstanding botany teacher In addition, Keller and Braun (1999) real estate values; these are some of the and field botanist, and a member of the discuss this species with excerpts quoted value-added benefits of trees. How many famous FRIENDSHIP 9 from Rock Hill, here: “The sporangia are 50–150μm of you remember the tree in your yard South Carolina. in diameter and 125–300 μm in total that you climbed during your youth or height. The silvery, persistent peridium built a tree house or played hide and References Cited looks very much like tinfoil and usually seek? One of the side effects of dead Bordelon, A., H.W. Keller, and R.J. remains attached to the apex of the or dying elms in rural environments O’Kennon. 2020. Rediscovery of columella.” The LM photographic image is the appearance of the highly prized Dentrothele (white crust fungus) in shown here (Fig. 9g) has a portion of morel mushroom in the spring months North Texas: the importance of urban the hollow stalk as a white slit in optical considered a delicacy by mycophiles. tree preservation. Texas Plant section. Furthermore, air bubbles are Conservation Conference, Botanical also sometimes trapped in the stalk Acknowledgments Research Institute of Texas, providing additional evidence that All photos by the author, unless Session 1, Floristics.

Spring 2021 FUNGI Volume 14:2 33 Bunyard, B.A. 2013. Morels: the name systematics, biology and use in Lado, C. 2005-2020. An on line game. FUNGI 6(1): 27–32. teaching. Ohio Biological Survey nomenclatural information system of Davison, P.G., and H.W. Keller. 2004. Bulletin New Series13(2): 1–182. Eumycetozoa. Real Jardín Botánico, Vertical distribution of liverworts Keller, H.W., and T.E. Brooks. 1976. CSIC. Madrid, Spain. http://www. within the forest canopy in the Corticolous myxomycetes V: nomen.eumycetozoa.com (consulted Southern Appalachians: contributions observations on the genus Echinostelium. January, 2021). to the All Taxa Biodiversity Inventory Mycologia 68: 1204–1220. Marshall, V.M., and H.W. Keller. 2018. of the Great Smoky Mountains Keller, H.W., and T.E. Brooks. 1977. Myxomycetes on American elms National Park. Evansia 21: 79–87. Corticolous myxomycetes VII: surviving Dutch elm disease in Texas. Eliasson, U.H., H.W. Keller, and J.A. contribution toward a monograph of Texas Plant Conservation Conference, Hutchison. 1988. Myxomycetes from Licea, five new species.Mycologia Botanical Research Institute of Texas, Arkansas. Mycotaxon 32: 375–398. 69: 667–684. p. 19. Everhart, S.E., and H.W. Keller. 2008. Keller, H.W., P. Davison, C. Haufler, and Martin, G.W., and C.J. Alexopoulos. Life history strategies of corticolous D.B. Lesmeister. 2003. Polypodium 1969. The Myxomycetes. University of myxomycetes: the life cycle, fruiting appalachianum: an unusual tree Iowa Press, Iowa City; 561 p. bodies, plasmodial types, and canopy epiphytic fern in the Great Moreno, G., C. Illana and M. Lizárraga. taxonomic orders. The International Smoky Mountains National Park. 2001. SEM studies of the Myxomycetes Journal of Fungal Diversity 29: 1–16. American Fern Journal 93: 36–41. from the Peninsula of Baja California Gilbert, H.C., and G.W. Martin. 1933. Keller, H.W., S.E. Everhart, M. Skrabal, (Mexico), III. Additions. Annals of Myxomycetes found on the bark of and C.M. Kilgore. 2009. Tree Botany Fennici 38: 225–247. living trees. University of Iowa Studies canopy biodiversity in temperate Parker, E.E., and H.W. Keller. 2003. in Natural History, Papers on Iowa forests: exploring islands in the sky. Correlation of pH with assemblages of fungi IV. 15(3): 3–8. Southeastern Biology 56(1): 52–74. corticolous myxomycetes in Big Oak Gilbert, H.C. 1934. Three new species of Invited paper. Tree State Park. Journal of the McNair Myxomycetes. University of Keller, H.W., and S.E. Everhart. 2010. Central Achievers Program, University Iowa Studies in Natural History. Importance of myxomycetes in of Central Missouri. Vol. XII Contributions from the Botanical biological research and teaching. (Issue 1): 4–8. Laboratories 16: 153–159. FUNGI 3(1): 29–43. Perry, B.A., H.W. Keller, E.D. Forrester, Hemmes, D.E., and J. Stallman. 2020. Keller, H.W., C.M. Kilgore, S.E. Everhart, and B.G. Stone. 2020. A new Morels in a bird’s nest. FUNGI 12(4): G.J. Carmack, C.D. Crabtree, and corticolous species of Mycena 41–43. A.R. Scarborough. 2008. Myxomycete section viscipelles (Basidiomycota), Keller, H.W. 1973. Myxomycetes from the plasmodia and fruiting bodies: unusual Agaricales) from the bark of a living Everglades National Park and adjacent occurrences and user friendly study American elm tree in Texas, U.S.A. areas, I. The Ohio Journal of Science techniques. FUNGI 1(1): 24–37. Journal of the Botanical Research 73(6): 364–369. Keller, H.W., and V.M. Marshall. 2019. A Institute of Texas. 14 (2): 167–185. Keller, H.W. 1998. Morels discovered at new iridescent corticolous River Legacy Parks. Living Science myxomycete species (Licea: Liceaceae: Scarborough, A.R., H.W. Keller, and J.S. Natural News 5(3): 2. Liceales) and crystals on American Ely. 2009. Species assemblages of tree Keller, H.W. 2004. Tree canopy biodiversity: elm tree bark in Texas, U.S.A. Journal canopy myxomycetes related to pH. student research experiences in Great of the Botanical Research Institute of Castanea 74(2): 93–104. Smoky Mountains National Park. Texas 13(2): 367–386. Snee, T. 2012. The last elm, the tree Dutch Systematics and Geography of Plants Keller, H.W., M. Skrabal, U.H. Eliasson, elm disease would leave behind. The 74: 47–65. and T.W. Gaither. 2004. Tree canopy University of Iowa, Iowa Now. Keller, H.W. 2005. Undergraduate biodiversity in the Great Smoky Snell, K.L., and H.W. Keller. 2003. research field experiences: tree canopy Mountains National Park: ecological Vertical distribution and assemblages biodiversity in Great Smoky Mountains and developmental observations of a of corticolous myxomycetes on five tree National Park and Pertle Springs, new myxomycete species of Diachea. species in the Great Smoky Mountains Warrensburg, Missouri. Council on Mycologia 96: 537–547. National Park. Mycologia 95: 565–576. Undergraduate Research Quarterly Kilgore, C.M., H.W. Keller, and J.S. Ely. Snell K.L., H.W. Keller, and U.H. Eliasson. 25(4): 162–168. (Invited Paper). 2009. Aerial reproductive structures 2003. Tree canopy myxomycetes and Keller, H.W. 2012. Myxomycete history on vascular plants as a microhabitat new records from ground sites in the and taxonomy: highlights from the for myxomycetes. Mycologia Great Smoky Mountains National past, present, and future. Mycotaxon 101: 303–317. Park. Castanea 68: 97–108. 122: 369–387. Kilgore, C.M., H.W. Keller, S.E. Everhart, Thompson, V.V. 1994.Morel: a lifetime Keller, H.W., and K.M. Barfield. 2017. A.R. Scarborough, K.L. Snell, M.S. of pursuit. Pamphlet published by the The Great Smoky Mountains National Skrabal, C. Pottorff, and J.S. Ely. 2008. Missouri Mycologial Society; 36 p. Park: The People’s Park. FUNGI 10(2): Research and student experiences using Wrigley de Basanta, D., and C. Lado. 44–64. the doubled rope climbing method. 2005. A taxonomic evaluation of Keller, H.W., and K.L. Braun. 1999. Journal of the Botanical Research the stipitate Licea species. Fungal Myxomycetes of Ohio: their Institute of Texas 2(2): 1309–1336. Diversity 20: 261–314. 34 FUNGI Volume 14:2 Spring 2021