Eastern Mojave Vegetation Autecology of Desert Elkweed Frasera albomarginata S. Watson (Syn: Swertia a.) Gentianaceae in the American Southwest (Continued)  
 

Tom Schweich  

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Topics in this Article:
Introduction
Literature Review
Field Work and Methods
Results
Taxonomy
Distribution
Growth Habits
Relationships to Soils and Other Plants
Life History
Discussion
Summary
Literature Cited
Appendix A -- Field Data
Communications Received.
 
This paper was originally presented at the 1999 Desert Research Symposium at the San Bernardino County Museum. The research is ongoing and the paper has been updated as new information becomes available.

You may notice a little schizophrenic appearance to names as I abandon Swertia as the genus and migrate to Frasera.


 

Taxonomy

 
  The type specimen of Frasera albomarginata Wats. is at US. There is an isotype at NY, for which an image is available online.

Literature Cited:
- Watson, Sereno, 1871.
Full Size ImageImage of the original description of Swertia albomarginata.

Species Lists: Frasera albomarginata  

The labels on the vouchers state that the collection locality was "S. E. Utah." However, Watson's original description of Frasera albomarginata Wats. gives the locality as "Near St. George in Southern Utah (Dr. Palmer, 1870)." Saint George is, of course, in southwestern Utah.
FRASERA ALBOMARGINATA. Slender, 2-3° high, glabrous, branching into an open panicle; branches and branchlets verticillate in fours or sometimes opposite; leaves verticillate in fours, narrowly oblanceolate, 2-4' long, 3-5" wide, obtuse or acute, margined with a silvery-white line and more or less undulate; upper leaves and bracts lanceolate from a clasping base, acuminate; pedicels spreading, 3-2' long; calyx-lobes 2-3" long, ovate-lanceolate; corolla 9" in diameter, the petals broad-oblong, acute, greenish yellow, dotted with black above the middle, the base deeper green; gland linear-oblong, fringed with a villous border, expanding at the top into a broad obcordate deep-green villous spot—Near St. George in Southern Utah, (Dr. Palmer, 1870.)

Literature Cited:
- Hickman, James C. (Ed.), 1993.

Locations: Saint George.  

The type specimen of Frasera albomarginata (S. E. Utah, 1870, Palmer (US)) is an entirely glabrous plant, as was indicated in Watson's description of the species. Specimens of the species examined in the University and Jepson Herbaria (University of California, Berkeley) include the type species and one variety, S. a. var. induta. Although, this variety is not recognized in Hickman (1993).
   

Literature Cited:
- Walter, Thomas, 1788.
Full Size ImageImage of first description of Frasera  

The first description of Frasera was by Thomas Walter (1788) in his Flora Caroliniana. We are very fortunate to see the original publication online at URL: http://www.botanicus.org/title/b12073714#. Thanks also to Missouri Botanical Garden for making the book and online image available. I have tried to give an English translation, and am open to corrections.

Latin English
TETRANDRIA1. MONOGYNIA2, &c. 87 Four Stamens, One Style, etc.
69. FRASERA. Cal.3 tetraphyllus , fol. lanceolatis, perfiftens. Stem four-leaved, leaves lanceolate, persistent
Cor. tetrapetala, petalis acuminatis, intus ad medium barbatis, incarnatis. Corolla four-petaled, petals acuminate, on the inside bearded at the middle, flesh-colored.
Stam. filamenta quatuor fubulata, longitudine corollæ, anthere oblongæ, incumbentes. Stamen filaments four tapering to a fine point, fused at the corolla(?), anthers oblong, separate(?).
Pift. germen fuperum, magnum ovatum. Stylus brevis. Stigma obtifu bifidum. Pistil ovary superior, greatly ovate, style short, stigma two-lobed.
Per. filiqua ovata acuminata unilocularis. Per. capsule ovate tapering to a point, single-locule
Sem. plurima compreffa marginata imbricata. Seed very much compressed with overlapping margins.
carolinienfis I. caule erecto, ramis4 floriferis verticilatis; pedunculis unifloris geminis, longitudine inæqualibus, axillaribus; foliis lanceolatis. erect stem, with whorled flowering branches; twinned or paired single-flowered peduncles, lenthwise inequal, axillary; leaf lanceolate
Notes:

1.TETRANDRIA: A Linnæan class of plants having four stamens.

  • 2.MONOGYNIA: A Linnæan order of plants, including those which have only one style or stigma.
  • 3. "Cal." must be an abbreviation of "caule" or stem.
  • 4."Ramis" is probably "ramus" or stem.
  • Literature Cited:
    - Kuntze, O. C. E., 1891.
    Full Size ImageImage of Kuntze revision of 1891  

     

    Literature Cited:
    - Card, Hamilton H., 1931.
    Full Size ImageCard, 1931  

     

    Literature Cited:
    - Threadgill, Paul F., and Jerry M. Baskin, 1978.
    Full Size ImageThreadgill and Baskin (1978) paper on Frasera  

     
      Variety albomarginata is the most common expression. It is found mostly on dry, sagebrush foothills and alluvial fans, extending into the pinyon-juniper zone, mostly from 4,500-7,600 ft.

    Literature Cited:
    - Kartesz, John Thomas, 1988.

    Locations: Clark Canyon. Harris Springs. Spring Mountains.  

    Variety induta (Tidestrom) Card, Ann. Mo. Bot. Gard., 18:275. 1931. is a rare expression in Nevada, ranging from Charleston Peak, Clark Canyon, Harris Springs and elsewhere in the Spring Mountains, Clark County; to southern Nye County. It is found in dry habitats, often with Cercocarpus and pinyon-juniper but extending into the yellow pine zone from 5,000-8,000 ft. (Kartesz, 1988). Kartesz states the variety is easily separated from the above expression by its glandular-hairy infloresence and unique foveae.

    Other articles: Wild Horse Canyon Road Wild Horse Mesa Field Notes Coll. No. 183 Frasera albomarginata at Coalpits Wash Utah Highway 9 Coalpits Wash
    Full Size ImageCollection No. 183, Wild Horse Mesa.
    Full Size ImageCollection No. 184, Coal Pits Wash, Utah.  

    183  184  Most of my collections of the species are from the eastern Mojave.

    Full Size ImageFrasera albomarginata flower.  
    The nectaries in Frasera are prominently placed on the corolla lobes, and called fovea. This can be seen in the photograph of the flower at left. Fovea is a Latin word for "small pit" and defined as, "a shallow cuplike depression or pit, as in a bone (Websters II, 1984)." Since we are speaking good Latin here, the plural is "foveae." The foveae seem to be prospective characteristics for distinguishing between subspecies of F. albomarginata and among species of the genus Frasera. In my examination of herbarium specimens of F. albomarginata, there seem to be five different shapes of foveae. These are diagrammed below.

    Full Size ImageFovae.  
    Adapting some of the terminology used in describing leaf bases and tips, these nectaries would be described as follows:

    (a) nectary linear pit, 2-lobed at tip, lobes rounded.

  • (b) nectary linear pit, 2-lobed at tip, lobe base rounded, tip retuse.
  • (c) nectary linear pit, 2-lobed at tip, lobe base rounded, tip emarginate.
  • (d) nectary obovate pit, 2 lobed at tip, lobe bases hastate, tip emarginate.
  • (e) nectary linear pit, 2 lobed at tip, lobe bases separate into 2 small round pits, rounded above, tip emarginate.
  •   I would like to be able to describe some sort of evolutionary order of increasing complexity and elaboration in the fovea from (a) to (e). However, at this time, I'll have to leave that as a possible construct, awaiting a testable hypothesis and testing.
      From my examination of herbarium specimens, I agree with separation of the variety induta on the character of glandular-hairy infloresence. Although, I would express the character as puberulent upper stems and bracts. I don't, however, find that the shapes of the foveae are distinctive for the variety.
      I identify the eastern Mojave specimens as S. a. var. albomarginata because the stems and bracts are glabrous, not puberulent, and the foveae are not unique.

    Literature Cited:
    - Kartesz, John Thomas, 1988.

    Locations: Charleston Peak. Spring Mountains.  

    Kartesz (1988) also states that var. induta is the westernmost expression of the species, with the type from rocky places in the pinyon and yellow pine belts, Spring (Charleston) Mountains, Clark County. This may be true. My eastern Mojave locations are just east of south of the Spring Mountains and Charleston Peak. Unless there are occurrences of F. albomarginata west of the Mid Hills or Providence Mountains, then the Spring Mountains are the westernmost location for the species.

    Literature Cited:
    - Kartesz, John Thomas, 1988.  

    Both this species and the closely related F. [Swertia] puberulenta are most likely evolved from Frasera speciosa (Kartesz, 1988).

    Literature Cited:
    - Chassot, P., S. Nemomissa, Y.-M. Yuan, and P. Küpfer, 2001.

    Other articles: Frasera albomarginata Chassot, et al. (2001)
    Full Size ImageFigure 1 from Chassot, et al. (2001)  

    Chassot et al. (2001) study of the phylogeny of Swertia showed that Swertia, as currently defined in regional floras or otherwise (e.g., Pringle, 1990), is not a monophyletic taxon when considering the molecular data. Rather, it is a strongly paraphyletic stem group. Their consensus trees are shown at left.

    My unschooled interpretation is that a number of somewhat related taxa that look similar have been lumped into Swertia. However, new molecular data shows many of them are more closely related genetically to other taxa in Gentianaceae than to other Swertia. This introduces confusion as to what Swertia really is and, therefore, what belongs in Swertia and what does not.

    Chassot et al. (2001) state that the generic concept of Swertia has never been viable, mainly because macromorphological characters for not exhibit clear enough patterns to unambiguously justify taxonomic units. That sounds to me like the argument that Pringle (1990) makes to keep Frasera in Swertia, is also used by Chassot, et al. (2001) to justify blowing up the genus Swertia.

    However, regardless of whether there is a further breakup of Swertia, Frasera does not belong there, and it should be recognized at the generic rank, i.e., as a genus.

    In California, Swertia perennis L. should remain in Swertia. Frasera albomarginata (S. Watson) Kuntze should be Frasera albomarginata S. Watson, and Swertia radiata (Kellogg) Kuntze should be Frasera speciosa Griesb.

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    Date and time this article was prepared: 5/18/2017 12:09:47 PM