The following Participating Institutions are custodians for this species in the CPC National Collection:
The Arboretum at Flagstaff
The conservation of Hedeoma diffusum is fully sponsored.
Joyce Maschinski, Ph.D. contributed to this Plant Profile.
Flagstaff pennyroyal is a small perennial herb which forms circular prostrate mats with numerous shoots. Its small leaves are arranged oppositely on delicate square stems. The small, irregular blue-lavender flowers can be found from late May to September, and are borne in clusters of 1-3 in leaf nodes. These flowers remain open for about 3 days, with fruit developing 2 to 3 weeks after pollination. Flowering occurs from late May through September. (Irving 1980)
Distribution & Occurrence
Hedeoma diffusum grows on outcrops of dolomitic upper Kaibab limestone at elevations of 6640-7500 feet (2024-2287 m). The plant prefers open spots with weathered limestone solution pockets filled with 4-6 inches of soil, but also grows in vertical cracks and around the edges of boulders. (Arizona Fish and Game Department 1999)
Over 40 species are found in association with Flagstaff pennyroyal. They include: ponderosa pine, gambel oak, Hedeotis pygmaea, Geranium caespitosum, and Festuca arizonica.
|60 locations in the vicinity of Flagstaff Arizona northern Arizona and locations along the rims overlooking Oak Creek Canyon.|
Conservation, Ecology & Research
Seed production is usually good, and seed life has been shown to be at least 5 years.
Seed dispersal occurs primarily by wind and water.
(Arizona Fish and Game Department 1999)
Protect limestone outcrops where the species is found
Continue to survey for additional sites
Investigate the basic biology and ecology of the species (incl. Substrate analysis, maximal canopy coverage, associates, and growth habitat trends).
Baker, B.S. Recommendations for the Preservation of Rare Plants and Unique Habitats Within the Chino Valley Ranger District, Central Arizona. Gen. Tech. Rep. RM-GTR-283. Proceedings of the Southwestern Rare and Endangered Plant Conference; September 11-14
Frankel, O.H.; Soule, M.E. 1981. Conservation and evolution. Cambridge, England: Cambridge University Press. 327p.
Phillips, B.G.; Crisp, D.L. Dalmatian toadflax, an invasive exotic noxious weed, threatens Flagstaff pennyroyal community following prescribed fire. Southwestern rare and endangered plants: proceedings of the third conference; September 25-28; Flagstaff,
Phillips, B.G.; Crisp, D.L. Dalmation Toadflax, and Invasive Exotic Noxious Weed, Threatens Flagstaff pennyroyal Community Following Prescribed Fire. Southwestern rare and endangered plants: proceedings of the third conference; September 25-28; Flagstaff,