12 de agosto de 2019

Confused names of Trifoliums with reflexed flowers

This is an attempt to sort out the confusion regarding the correct names to apply to several species of Trifolium with reflexed flowers.

Trifolium productum occurs in northern California and Oregon, including the Klamath Mountains, Cascade Range, and northern and central Sierra Nevada. It was formerly known as T. kingii subsp. productum, and many published books simply refer to it as T. kingii.

Trifolium dedeckerae occurs in the southern Sierra Nevada (south of the San Joaquin-Kings River divide) and in the White Mountains. It is listed in the Jepson Manual 2nd Ed. (2102) as T. kingii ssp. dedeckerae.

Trifolium kingii as currently delimited occurs only in southern Utah and adjacent parts of Nevada and Colorado. It includes two subspecies: ssp. kingii occurs in southern Utah and southwestern Colorado, ssp. macilentum is in southern Nevada and southwestern Utah.

And just to make it a bit more fun, T. kingii ssp. macilentum was formerly considered a full species and is listed as such in Intermountain Flora, and it included the previously mentioned T. dedeckerae as T. macilentum var. dedeckerae.

Publicado el 12 de agosto de 2019 04:03 por twr61 twr61 | 7 comentarios | Deja un comentario

22 de julio de 2019

Some notes about Calochortus nudus, C. minimus, and hybrids

Two closely related species of Calochortus occur in the mountains of California and southern Oregon; C. nudus in the Klamath Range/Mt Shasta area and C. minimus in the Sierra Nevada from Lake Tahoe southward. In between the areas where the species occur in their pure form is a large region covered by intermediate types which are believed to be derived from hybridization and introgression with the parent species.

Marion Ownbey described the situation in his 1940 Monograph of the Genus Calochortus (https://www.biodiversitylibrary.org/page/16163357). He first described C. minimus in this paper, and chose to assign the intermediate forms to C. nudus:

In the vicinity of Mount Shasta, C. nudus is uniform, but south of the Pit River it occurs in pure stand with decreasing frequency as one passes southward. In eastern Eldorado County and southward, only the closely related C. minimus occurs. Between the two geographically, there is a bewildering assortment of plants showing independent recombination of the various morphological characters which separate these two species. Such a population can be explained only as the result of long-continued hybridization and probably repeated back-crossing, particularly with C. nudus. Pure C. minimus does not seem to occur within the area, so the entire population is here referred to C. nudus. It should be pointed out, however, that occasional specimens are so close to C. minimus that they can be distinguished only by geographical criteria.

From the evidence at hand, it appears that at one time these species were separated by a geographical barrier which allowed evolution to proceed in different directions on either side. As a result there was developed a robust northern race, with larger flowers, rounded petals, taller stems, proportionately shorter and broader basal leaves, and erect fruits which are acute at both ends. It is fortunate that this race has persisted in a nearly pure state in the Mount Shasta Region, and at numerous stations in the northern Sierra Nevada.

The southern race is smaller in all respects, the petals acute, the stems very short, the basal leaves greatly exceeding the inflorescences, the fruits obtuse and nodding on slender, strongly deflexed pedicels. This race now occupies the southern Sierra Nevada, from eastern Eldorado County southward to Tulare County, in a practically pure condition. The combinations of morphological criteria which separate the southern from the northern race are certainly of specific value. It is only when the intervening population is considered that there is any possibility of another interpretation.

Today the barrier which once separated these two species has disappeared, and they have come together again. Since they were presumably derived from the same stock, the hybrids are fertile and interbreed both among themselves and with both parent species. The result should be a population possessing the characters of both parents, but in different combinations. This is exactly what we find. It is impossible to separate such a population completely into two, or even a dozen, categories, yet the morphological differences between C. nudus and C. minimus do not permit their inclusion within a single species. Even if such an assignment were possible, it would be undesirable, as it would obscure their probable genetic relationships.

Regional floras have followed Ownbey, for example "A Flora of Lassen Volcanic National Park, California" (Gilllett et al, 1995) lists only C. nudus as occurring in the park.

Fifty years later Ness et al (1990) carried out additional studies which supported the hypothesis that the intermediate forms in the northern Sierra result from hybridization. Their research suggested that the hybrids are no more closely related to C. nudus than to C. minimus. (https://www.researchgate.net/publication/230852138_An_Examination_of_Polyploidy_and_Putative_Introgression_in_Calochortus_Subsection_Nudi_Liliaceae)

Patterson and Givnish (2003) conducted DNA analysis to study evolution of Calochortus. Although they do not specifically discuss C. nudus and C. minimus, their analysis indicates that these two are not sister taxa; that is, each is more closely related to other species of Calochortus that they are to each other. (https://courses.botany.wisc.edu/botany_940/15Stebbins/chapter%206%20papers/Patterson%202004%20New%20Phytologist.pdf)

Publicado el 22 de julio de 2019 23:25 por twr61 twr61 | 3 comentarios | Deja un comentario

06 de octubre de 2018

The Fungi that make Alder Tongue Galls

Although I have probably walked past them dozens of times, I first noticed alder tongue gall a few months ago when I noticed what appeared to be bright red flowers on an alder shrub. I took a few photos and added the observation to iNat, and the artificial intelligence suggested an identification of Taphrina alni.

I was intrigued, and tried to find out more about these strange-looking growths, but information on the web was pretty scanty. The only references I was able to locate indicated that T. alni occurred in Europe, and had recently been found in Great Britain. There was no indication that it was a new world species.

With the obligatory disclaimer that I am not a mycologist (nor do I play one on TV) my research so far indicates that there are three species of Taphrina that cause alder tongue gall, which can be distinguished by microscopic or molecular analysis, but are generally differentiated by geographic distribution. These species are:

Taphrina alni, which occurs in Europe. The studies cited below indicate that T. alni has not been found in North America with the exception of some specimens collected in Alaska under the synonym Taphrina amentorum.

Taphrina robinsoniana occurs in eastern North America.

Taphrina occidentalis occurs in western North America.

Ray (1939) is the primary reference; he found that alder tongue gall in North America is not caused by T. alni but rather by T. robinsoniana and by a previously undescribed fungus which he named T. occidentalis (https://www.jstor.org/stable/3754433).

Mix (1949) in his "Monograph of the Genus Taphrina" accepted Ray's findings with regard to the alder tongue gall forming species, with the exception that Ray had described another species T. rugosa which was determined to be a juvenile form of T. robinsoniana (https://www.biodiversitylibrary.org/part/16125#/summary).

Dugan & Newcombe (2007) summarized the state of knowledge with regards to alder tongue gall fungi and noted the discovery of specimens in Idaho consistent with Ray's description of T. occidentalis. They note that additional specimens of T. amentorum have been found in Alaska but not elsewhere. They also note that the "relation between T. amentorum and T. occidentalis appears not substantially investigated since the publications of Mix (1940) and Ray (1939)." (https://www.researchgate.net/publication/43270414_New_records_for_powdery_mildews_and_Taphrina_species_in_Idaho_and_Washington).

Rodrigues & Fonseca (2003) found that T. alni and T. robinsoniana can be differentiated using DNA analysis. T. robinsoniana may in fact encompass more than one cryptic species. T. occidentalis was not included in their study (http://ijs.microbiologyresearch.org/content/journal/ijsem/10.1099/ijs.0.02437-0?crawler=true&mimetype=application/pdf).

Publicado el 6 de octubre de 2018 20:52 por twr61 twr61 | 4 observaciones | 1 comentario | Deja un comentario