January 24, 2017

White Juniper Fungus, Robergea albicedrae

A common sight across north central Texas and the Edwards's plateau is a white or light gray fungus that appears as a whitening pattern on the branches of young Juniperus Ashei trees. Most folks that venture out into wooded areas where J. Ashei occurs will notice the distinctive pattern formed by this fungus. But very few know exactly what it is. With this journal post, I hope to help fill that gap by providing a useful summary of this common fungus along with a list of references for further study. I also want to acknowledge Mark Gustafson who described this fungus in an entry in his recent book, A Naturalist's Guide to the Texas Hill Country.

Robergea albicedrae

In 1910, Heald and Wolf described this fungus species and assigned it the name Cyanospora albicedrae. The generic name Cyanospora was based on the (apparently incorrect) observation that the spores were green. The following year Saccardo and Traverso corrected this and assigned the species to the genus Robergea.

When you see this fungus in the field, look for small gray nodules on the whitened patches. These contain the fruiting bodies from which the filamentous spores are expelled. The close-up photo below shows an example of these gray nodules.

Robergea albicedrae

This fungus occurs only on J. Ashei. It is quite common on the branches of young trees, especially in shaded conditions such as dense brakes. In fact, it is so common that it can be used as a characteristic feature in the identification of J. Ashei. Since it only occurs on this one species of tree, the range of R. albicedrae can be expected to be within the range of J. Ashei. The map below shows the natural range of J. Ashei.

Juniperus Ashei distribution

According to the 1910 paper by Heald and Wolf, the fungus is probably parasitic on the host tree. They also indicated that branches of the tree or even the entire tree could be killed by the effects of the fungus corroding the bark and destroying the cambium layer. A 2008 paper by Miller and Lemke supported the possibility that the fungus is parasitic on J. Ashei. They found that tree size (height and basal trunk diameter) decreased corresponding to increased fungal load.

References

Heald, F. D., and F. A. Wolf. “The Whitening of the Mountain Cedar, Sabina Sabinoides (H.B.K.) Small.” Mycologia, vol. 2, no. 5, 1910, pp. 205–212. www.jstor.org/stable/3753277.

Sherwood, M. A. "The Ostropalean Fungi. I." Mycotaxon (1977).

Miller, S. A. and D. E. Lemke. 2008. Determining the relationship between Cyanospora albicedrae (Ascomycota: Stictidaceae) and Juniperus Ashei (Magnoliophyta: Cupressaceae). Annual meeting of the Texas Academy of Science, Texas A&M University, Corpus Christi.

Gustafson, Mark. A Naturalist's Guide to the Texas Hill Country. Vol. 50. Texas A&M University Press, 2015.

Juniperus Ashei range map by Elbert L. Little, Jr., of the U.S. Department of Agriculture, Forest Service [Public domain], via Wikimedia Commons

Posted on January 24, 2017 01:54 by billdodd billdodd | 1 observations | 4 comments | Leave a comment

November 04, 2016

Stanfield's Beebalm, Monarda stanfieldii

On Oct 30, 2016, botanist Bill Carr led a native plant identification field trip to the private Spicewood Ranch in Burnet County, TX. The field trip was organized by Environmental Survey Consulting.

Bill showed us a population of the Texas endemic Stanfield's Beebalm, Monarda stanfieldii. He admitted that he had originally misidentified it as M. punctata. But on further study realized it was M. stanfieldii.

The major distinguishing feature between these two species is that in M. stanfieldii, the mouth of the calyx is closed by a dense mass of white to silvery hairs. In M. punctata the calyx is open and merely ciliate.

And fortunately, these distinguishing characters can still be observed after the leaves and corollas have dried up and disappeared (as they had in this population in late October).


First, see this photo of M. punctata from eiu.edu. Note that the mouth of the calyx is ciliate, but still open:

Monarda punctata



Now compare with this photo of M. stanfieldii I took during the field trip. Note that the mouth of the calyx is closed with a mass of white hairs:

Monarda stanfieldii

You can see even more detailed photos of this specimen in my observation attached below. Be sure to select the "original" size in order to see all the glorious macro detail.



Also, see this Monarda key for reference:

http://www.lib.utexas.edu/lsl/Mints/monarda/monakey.html



M. stanfieldii has a very limited range, restricted to sandy areas along the Colorado and Pedernales Rivers on or downstream of the Llano Uplift (Blanco, Burnet, Gillespie, Llano and Travis counties). But note that BONAP shows a specimen record from Robertson County. This seems out of range based on the current understanding of the desired ecological region of this species. Here is the M. stanfieldii distribution map from BONAP (Robertson County is the easternmost county in yellow on the map):

Monarda stanfieldii



The details above are summarized from the notes and discussion provided by Bill Carr. Any errors are surely mine.

Posted on November 04, 2016 21:38 by billdodd billdodd | 1 observations | 4 comments | Leave a comment

Archives