Tooth and coral fungi are both broad categories of taxonomic classification of fungi based on physical characteristics. In fact, years of observations have shown that species in these categories are not necessarily closely related. Coral fungi, or clavarioid fungi, have coral-like elongated structures. They are rather difficult to identify due to the resemblance between many of the species. On the other hand, tooth fungi, or hydnoid fungi, are much easier to differentiate. Apart from all presenting a spine-like surface usually pointing downwards, tooth fungi can appear in a wide variety of shapes, colours and textures.
Both study groups –clavarioid fungi and hydnoid fungi –belong to the order basidiomycota. Despite their similar mechanism of reproduction, clavarioid fungi and hydnoid fungi have very distinctive physical properties.
As a group, clavarioid fungi do not belong to any natural taxon; the group solely consists of genera and species which possess a similar structure. As a physical trait, the fruit bodies of clavarioid fungi grow upwards. These fruit bodies are in the form of unbranched simple stalks or branched stalks. The stalks serve an important purpose in fungal reproduction – they elevate the spore producing cells, and increase the probability for long range dispersal. As more than thirty genera of clavarioid fungi are known – the most common of these being Ramaria – identification is extremely difficult, and must sometimes be done on the microscopic level. The colors of these fungi include white, red, orange, yellow, tan, and purple.
Similar to clavarioid fungi, hydnoid fungi are not taxonomically a natural taxon either, but they have a similar morphology in that their fruit bodies produce tooth-like spines (Dai 2010). These teeth-like spines grow downwards and are always orientated so that they will be exactly perpendicular to the ground. During reproduction the tapered teeth allow for the produced spores to fall straight down to the earth. Many hydnoid fungi are wood-inhabiting saprophytic species, but some of them are definitely mycorrhizas (Dai 2010). There are few species of hydnoid fungi, and even fewer common species which allows for easier identification.
Coral and tooth fungi both play an important role in forest ecology as species within these categories are ectomycorrhizal (i.e. many in Hydum and Ramaria genus) or saprophytic (i.e. C.pyxidata, H.coralloides, C.septentrionale) (Ostry et al. 2011).Within the last decade, more research has been centered on understanding the complex ectomycorrhizal relationship that occurs between certain tree roots and fungi since it has many ecological implications, such as the diversity and distribution of these species(Molina 1994). Whereas saprophytic fungi feed mostly on decaying wood and contribute to decomposing litter and nutrient cycling, ectomycorrizal fungi form mantles that cover the roots of certain trees and produce a complex network where nutrients are exchanged between the fungal hyphae and the roots, meaning that both species rely on each other for survival (Molina 1994).
Not all trees necessarily participate in this exchange and if they do, it is only with certain ectomycorrhizal fungi (Knudson 2012). This determines which forest types certain coral and tooth fungi will live in and how they will be distributed. For instance, as discussed in a recent paper on the Ramaria genus in Minnesota, ectomycorrhizas within this genus interact specifically with Abies (Fir), Cedrus (Cedar), Fagus (Beech), Larix (Larch), Picea (Spruce), Pinus (Pine) and Quercus (Oak) trees (Knudson 2012). A recent study also demonstrated that competition for root tips and soil resources between ectomycorrizal fungi has a direct influence on the structure and distribution of their community, however how these competitive interactions unfold is still not fully known (Kennedy 2010).
Knowing the ectomycorrhizal or saprophytic characteristics of our study species, we asked ourselves what is the distribution and diversity of coral and tooth fungi in the Morgan Arboretum. We hope this information can give us an idea of the tree diversity by looking at known ectomycorrhizal relationships as well as the amount of dead trees present in the ecosystem used by saprophytic fungi.
Our methods used during the lab periods all revolve around visual observation. We start by choosing three areas of the arboretum: a beech forest, a coniferous forest and a mixed deciduous forest. We go to different areas every lab so we do not observe the same fungus twice. We then spend twenty five minutes in each search area searching. By spreading out and walking in one direction, we manage to cover a lot of ground. Once a coral or tooth fungus is spotted, we stop our timer and regroup to identify it using field guides, measure it, note down its habitat and take a picture of the tree canopy. We take a picture of the tree canopy to be able to measure the amount of light through Photoshop by looking at the colour of pixels. To keep track of our observations, we use the application iNaturalist which has proven to be very helpful. We put in an equal amount of effort everywhere we search so our results are as accurate as possible.
Because of the limitations related to morphology-based observations, DNA analysis methods are now being used to gain a better understanding of the phylogenetic relationships between species. For instance, a recent study supports the theory according to which the coral-shape structure of the clavarioid fungi is the product of evolutionary convergence (Dentinger & David, 2006), thus that the species aren’t all closely related. The results of the experiment also suggest that some classifications would need to be reconsidered and that a new genus, Alloclavaria, should be created. After all, science is a never ending quest! Theories need to be constantly called into question and adapted. To keep track of what we are doing, follow us on twitter: MacShrooms (@MacFungiHunters)!
Dentinger, Bryn T. M.; McLaughlin, David J. “Reconstructing the Clavariaceae using nuclear large subunit rDNA sequences and a new genus segregated from Clavaria”. Mycologia. 17 Jul. 2006. Web. 25 October 2013.
Kennedy, Peter. “Ectomycorrhizal fungi and interspecific competition: species interactions, community structure, coexistence mechanisms, and future research directions.” New Phytologist 187.4 September 2010: 895-910. Science Direct. Web. 25 October 2013.
Molina, Randy. 1994. “The Role of Mycorrhizal Symbioses in the Health of Giant Redwoods and Other Forest Ecosystems” Gen. Tech. Rep. PSW-151. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station. 81 p. Web. 25 October 2013.
Ostry, Michael E.; Anderson, Neil A.; O’Brien, Joesph G. 2011. “Field guide to common macrofungi in eastern forests and their ecosystem functions.” Gen. Tech. Rep. NRS-79. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station. 82 p. Web. 25 October 2013.
Pickles, Brian J., David R. Genney, Ian C. Anderson and Ian J. Alexander. “Spatial analysis of ectomycorrhizal fungi reveals that root tip communities are structured by competitive interactions.” Molecular ecology 21.20 October 2012: 5110-5123. Science Direct. Web. 25 October 2013.