|Species Fact Sheet
Scientific Name: Rhizopogon bacillisporus A. H. Smith
Type Locality: Along a road at Tilly Jane Forest Camp, Mt. Hood National Forest, Hood River Co., Oregon, Oct. 1, 1947.
Holotype: Smith 27136
Fruiting Body about 5 cm, subglobose, glabrous, exterior surface apparently lacking rhizomorphs (mycelial strands), palid fresh and scarcely changing (dingy buff) dry, not staining when injured, peridium (surface tissue) somewhat separable; dry peridium olive with FeSO4, pale dingy vinaceous-brown with KOH. Stalk externally and internally absent. Spore Mass olive-buff fresh, ochraceous-buff dry, chambers minute, consistency friable and easy to section. Spores 5-6 x 1.7-2 um, rod-shaped, hyaline in KOH, yellowish in Melzer's sol., smooth, thin-walled, basal scar very indistinct.
Rhizopogon is one of several genera included among the "false truffles". There are perhaps four groups of fleshy fungi with which species of Rhizopogon are likely to be confused: 1) puffballs, 2) gastroid agarics, 3) other "false truffle" genera, and 4) true truffles. False truffles, puffballs and gastroid agarics are included within the Gasteromycetes - basidium-producing fungi whose spores are produced internally and not forcibly discharged from the basidia. The spore mass of puffballs (Lycoperdon and allies) is usually white, firm, and without readily discernable chambers when young, and becoming powdery and rather quickly dispersed at maturity. The fruiting bodies of puffballs are usually found aboveground. While the presence of a cap and stalk is clearly evident in some gastroid agarics, species of Endoptychum, Brauniellula or Thaxterogaster may bear a stronger resemblance to false truffles. However, dissection of a gastroid agaric will reveal at least some evidence of a percurrent stalk (one that extends through the spore mass to the top of the cap). At maturity, the sporocarps of gastroid agarics are usually found partially or fully aboveground. Among other genera of false truffles (e.g., Alpova, Gautieria, Hydnangium, Hymenogaster, Hysterangium, Leucophleps, Martellia and Truncocolumella) , Rhizopogon generally is distinct in exhibiting the following set of features: 1) an exterior surface often overlain with soft mycelial strands (rhizomorphs), 2) spore mass composed of minute, generally non-gelatinous chambers (best seen with hand lens), 3) stalk (basal and within spore mass) typically lacking and 4) spore surfaces smooth. Microscopically, true truffles are readily differentiated from species of Rhizopogon by the presence of sexually produced spores borne within asci. Macroscopically, however, fruiting bodies of true truffles will, as is typically true of Rhizopogon, show no evidence of a stalk, either basal, or within the spore mass. The interior of a true truffle, however, will typically differ from that of Rhizopogon species in being either 1) solid and marbled with veins, or 2) completely hollow or with quite evident folds and chambers. Because of the need to recognize multiple, subtle, microscopic anatomical features and use chemical staining procedures, it is probably unrealistic to expect a lay mycologist to do more than recognize that a fleshy fungus specimen is likely to be included in the genus Rhizopogon. Identification to species will almost certainly require the services of a Rhizopogon "expert".
Life History: This species is probably ectomycorrhizal with Pinaceae and depends on mycophagy (consumption by animals) for spore dispersal.
Range, Distribution and Abundance: Rhizopogon bacillisporus is a regional endemic known from perhaps four collections. In Oregon, known from Tilly Jane Campground, Mt.Hood National Forest, Hood River Co., and Burns Ranger District, Malheur National Forest, Harney Co. Also known from Medicine Bow Mtns., Albany Co., Wyoming. A single collection from Mt. Adams, Gifford Pinchot National Forest, Skamania Co., Washington, has been provisionally assigned to this species.
Habitat Associations: No information.
Threats: With the assumption that this species is ectomycorrhizal, it is reasonable to assume that as with ectomycorrhizal fungi in general, threats to the species particularly include activities/events that threaten to damage the mycelium. While not entirely consistent, the literature appears to amply demonstrate that moderate to severe fire, removal of a large percentage of host plants (with attendant reduction in canopy cover) and/or of large woody debris, and soil compaction can reduce both the biomass and species diversity within a community of ectomycorrhizal fungi. Attendant reductions in production of false truffles may, in turn, potentially reduce dispersal of their spores by small mammals.
Conservation Considerations: Revisit known localities to confirm persistence and determine extent of populations. Conduct surveys to locate new populations. Consider buffering known sites from adjacent vegetation management activities. Consider vegetation management activities within known site buffer that are likely to maintain or improve ectomycorrhizal fungal habitat quality (e.g., moderate hand-thinning of an overstocked stand or augmenting a deficient volume of coarse woody debris). When conducting vegetation management activities in areas with good habitat potential, consider leaving scattered and clumped host trees and ample coarse woody debris while minimizing soil compaction and burn severity of activity-related fires.
Conservation Rankings and Status:
Global: G2G3; Oregon: S1
ORNHIC List 3
Prepared by: Rick Dewey, Deschutes National Forest, March 2009
Arora, David. 1979. Mushrooms Demystified - A Comprehensive Guide to the Fleshy Fungi. Ten Speed Press, Berkeley, California. 959 pp.
Cushman, Kathleen and Rob Huff. 2007. Conservation Assessment for Fungi Included in Forest Service Regions 5 and 6 Sensitive and BLM California, Oregon and Washington Special Status Species Programs. R6 USFS and OR/WA BLM Interagency Special Status/Sensitive Species Program (ISSSSP).
Ferriel, Jenifer and Katie Grenier. 2008. Annotated Bibliography of Information Potentially Pertaining to Management of Rare Fungi on the Special Status Species List for California, Oregon and Washington. R6 USFS and OR/WA BLM Interagency Special Status/Sensitive Species Program (ISSSSP).
Fogel, Robert. 1994. Report on Fungi from the Columbia Basin Deposited in the University of Michigan Herbarium. Interior Columbia Basin Ecosystem Management Project, Science Integration Team - Terrestrial Staff. December 7, 1994. 21 pp. + 5 appendices.
MICH Fungus & Lichen Database Query for Specimen Data.
Oregon Natural Heritage Information Center. 2007. Rare, threatened and endangered species of Oregon. Oregon Natural Heritage Information Center, Oregon State University. Portland. 100pp.
Smith, Alexander H. and S. M. Zeller. 1966. A Preliminary Account of the North American Species of Rhizopogon. Memoirs of The New York Botanical Garden 14(2): 1-177.
USDA Forest Service. 1995. Report on Fungi. Prepared by Michael A. Castellano for Interior Columbia Basin Ecosystem Management Project.