Seed germination characteristics of Chrysothamnus nauseosus ssp. viridulus (Astereae, Asteraceae)

Rubber rabbitbrush ( Chrysothamnus nauseosus [Pallas] Britt. ssp. viridulus ) may prove to be a source of high-quality cis-isoprene rubber, but its establishment is limited by a lack of information on seed germination. Consequently, seeds were germinated at alternating temperatures (5–15, 5–25, 15–25, and 20–30 C) in light and dark as well as constant temperatures (15–40 C with 5-C increments) to determine temperature response. Seeds were also germinated in solutions of polyethylene glycol 6000 (0 to –5 bar), salinity regimes (1, 17, 51, and 86 mM) at all the above-mentioned temperatures to determine salinity and temperature interaction. The hormones GA 3 (0, 2.9, 29.0, and 58.0 um) and kinetin (0, 4.7, 23.5, and 47.0 um) were used to study their effect on overcoming salt- and temperature-induced germination inhibition. Seeds of C. nauseosus ssp. viridulus were very sensitive to low temperature. Best germination was achieved at 25 and 30 C, but these seeds also germinated at a higher temperature (35 C). The seeds of rabbitbrush germinated at both constant and alternating temperatures. Light appears to play little or no role in controlling germination of the seeds of rubber rabbitbrush. However, seeds of rabbitbrush were sensitive to salinity, and seed germination was progressively inhibited by increase in salt concentration, although a few seeds still germinated at the highest saline level. Progressively higher concentrations of polyethylene glycol also progressively inhibited germination. Suppression of seed germination induced by high salt concentrations and high temperatures can be partially alleviated by the application of either GA 3 or kinetin.     

Chrysothamnus nauseosus ssp. uintahensis: a stabilized hybrid

Chrysothamnus nauseosus ssp. uintahensis (Asteraceae) is formally described and illustrated. The new subspecies represents stabilized hybrids that most probably have C. nauseosus ssp. hololeucus x C. parryi ssp. attenuatus ancestry. Morphological and anatomical comparisons are made among the putatively related taxa.        

Seasonal changes of selected secondary plant products in Chrysothamnus nauseosus ssp. turbinatus

Previously, physiological studies of rubber and resin production during the growing season of Chrysothamnus nausceosus ssp. turbinatus indicated a negative correlation between rubber and resin content. The resin was highest in the spring and lowest in the summer, whereas rubber was highest in the summer and lowest in the spring. Individual compounds were followed during the growing season to see if they correlated with the rubber or resin trend. The total compounds in the cyclohexane fraction followed the resin pattern. Individual compounds varied in their changes during the growing season. Limonene, for example, was negatively correlated with rubber production, whereas β cubebene was positively correlated. The possible metabolic pathways between resin and rubber are discussed.     

Chloroplast ultrastructure in the desert shrub Chrysothamnus nauseosus ssp. albicaulis

Ultrastructure of the chloroplasts of white rubber rabbitbrush ( Chrysothamnus nauseosus (Pallas) Britt. ssp. albicaulis ) was observed with electron microscopy. In addition, leaf anatomy was observed with light microscopy. Previously, it had been reported that the leaves of this desert shrub exhibited a relatively high rate of photosynthesis when compared to other C 3 plants. Comparisons with chloroplasts of other C 3 and C 4 plants demonstrated a reduced amount of granal stacking in the rabbitbrush. However, the classification of rabbitbrush as a C 3 plant is confirmed. RUBP-carboxylase concentration is reported at about 450 mg · ml -1 stromal space based on the estimation of 1 mg of chlorophyll per 25 ul of stromal space in a normal C 3 chloroplast and data from an assay to determine the ratio of RUBP-carboxylase to chlorophyll.     

High rates of photosynthesis in the desert shrub Chrysothamnus nauseosus ssp. albicaulis

  Basic aspects of photosynthesis were investigated in white rubber rabbitbrush ( Chrysothamnus nauseosus (Pallas) Britt. ssp. albicaulis ), a common C 3 deciduous shrub native to arid regions of the western U.S. Under favorable field conditions, net photosynthesis (P n ) ranged from 36 to 73 mgCO 2 · dm – 2 · hr – 1 , which is relatively high for a woody species. The leaves from the actively growing flowering shoots exhibited higher P n than those on the vegetative shoots. P n also varied according to the age of the leaves and the location of the plants. P n did not light saturate even at quantum flux densities (QFD) equivalent to full sunlight. The light compensation point was relatively high (ca 100 μ mol · m – 2 · S – 1 ), perhaps due to the presence of a tomentose vestiture on the leaf surface. At high QFD's, the stomatal conductance was high (ca 520 mmol · m – 2 · s – 1 ) for a woody species. RUBP - carboxylase content of the leaves ranged from 20 to 22 mg per gram F.W., which is similar to that found in most C 3 crop species. These results suggest that rabbitbrush is able to maintain high rates of P n , at least under nonstressed conditions.           

A new species of fossil Chrysothamnus (Asteraceae) from New Mexico

The new, presumably extinct species, Chrysothamnus pulchelloides, is formally described and illustrated. The plant materials came from Holocene packrat middens. Anatomical and phyletic relationships of the fossil species to extant taxa are discussed.     

Haplopappus alpinus (Asteraceae): a new species from Nevada

The new species, Haplopappus alpinus of section Tonestus, is formally described and illustrated. It is endemic to the high mountains of central Nevada. Vegetative and floral morphology of related species is detailed. The new species appears to be most closely related to H. eximius but also demonstrates close affinity to H. aberrans (all three are diploids with n = 9).     

Feeding behavior and performance of a rabbitbrush leaf-beetle ( Trirhabda lewisii ) feeding on Chrysothamnus nauseosus regrwoth after fire

Fire often positively affects the growth and nutrient content of plants regrowing after a burn. These changes have been associated with preferential feeding by herbivores in burned areas. In this study in southeastern Wyoming, Chrysothamnus nauseosus Pursh (rubber rabbitbrush) regrowing after a fire produced new shoots with a distinct growth form. Shoots were longer than those on unburned control sites and had longer leaves with longer internodes between leaves. We conducted feeding trials to detect whether C. nauseosus shoots regrowing after fire were nutritionally superior to shoots from unburned plants for the specialist leaf beetle, Trirhabda lewisii Crotch (Coleoptera: Chrysomelidae). We also measured C:N ratios and nitrogen and water contents of leaves from burned and unburned plants. Trirhabda lewisii adults preferred shoots from burned plants when given a choice. The beetles ate similar amounts of burned and unburned plants when fed only a single type. Females that were fed either burned or unburned plants did not differ in number of eggs laid. Chemical analyses revealed no significant differences in nitrogen or water content of leaves from burned versus unburned plants. Carbon-to-nitrogen ratio of burned plants was marginally lower compared with unburned plants. In contrast to previous studies, which suggest that herbivore attraction to burned areas leads to enhanced performance, our study shows that performance is not necessarily enhanced after fire.     

Reproduction and demography of Townsendia aprica (Asteraceae), a rare endemic of the Southern Utah Plateau

Townsendia aprica (Asteraceae: Astereae), a rare pulvinate perennial of the Southern Utah Plateau, was listed as threatened under the U.S. Endangered Species Act in 1985. Here we report on the reproductive biology and pollination of this little-known species and provide an estimate, for a single site-year, of size-specific reproductive effort. Last Chance townsendia appears a short-lived perennial that begins reproducing in its 2nd year (1.5-2.0 cm diameter). Maximum reproductive effort is attained with the 2.5-4.0 cm diameter size class: 38% of these plants produced 84% of the flower heads. Few plants survived past the 4-cm size class. The species is primarily self-incompatible: neither autogamous nor geitonogamous breeding system treatments produced a significant number of achenes. Unlike some populations of some congeners, the Ivie Creek population was not apomictic. Outcrossing is the primary means of reproduction and native solitary bees are the most important pollinators. Paramount are several species in the genus Osmia , and the ground-nesting species Synhalonia fulvitarsis , which nests among the T. aprica plants. Synhalonia fulvitarsis also visits a contemporaneous blooming phlox ( P. austromontana ), which may facilitate pollination of the rare townsendia. The Townsendia-Phlox-Synhalonia interaction may represent another example of why we must consider communities rather than individual species in our conservation efforts.     

Range extension of Helianthus spp. (Asteraceae) in Arizona and Utah

Two populations of Helianthus niveus (Benth.) Brandegee ssp. canescens (A. Gray) Heiser were discovered in northern Arizona extending the range 300 miles north for this species. Helianthus deserticola Heiser range was extended 100 miles east in both Arizona and Utah.     

Haplopappus crispus and H. zionis (Asteradeae): new species from Utah

Two groups of glabrous, narrow-leaved Chrysothamnus viscidiflorus (Asteraceae) are perceived, and appropriate taxonomic combinations are made, i.e., C. v. ssp. viscidiflorus var. stenophyllus and C. v. ssp. axillaris. The two are fairly distinct geographically, and they can be separated by floral morphology. A key to all species of section Chrysothamnus (to which C. viscidiflorus belongs) is given.     

New taxa of thistles ( Cirsium ; Asteraceae) in Utah

  Described are several new taxa of the genus Cirsium that occur in the state of Utah: C. eatonii (Gray) Robins, var. harrisonii Welsh; C. eatonii var. murdockii Welsh; C. ownbeyi Welsh; C. scariosum Nutt. var. thorneae ; and C. virginensis Welsh.     

A new pulvinate Eriogonum (Polygonaceae) from Utah

A new species of pulvinate wild buckwheat, Eriogonum soredium (Polygonaceae, Eriogonoideae) is described from near-barren limestone slopes in the Grampian Hill area near Frisco, Beaver County, Utah. The new species is outwardly similar to E. shockleyi S. Wats, but may be readily distinguished by its glabrous (not pubescent) flowers and fruits, generally smaller leaves, more numerous involucres per head, turbinate (not campanulate) involucres with 5, rarely 4 (not 5 to 10) teeth, and the smaller flowers.     

Lahontan sagebrush ( Artemisia arbuscula ssp. longicaulis ): a new taxon

A new subspecies of Artemisia arbuscula is described, A. arbuscula ssp. longicaulis Winward & McArthur, ssp. Nov. This taxon is a landscape dominant in portions of northwestern Nevada and adjacent California and Oregon at elevations from 1050 to 2000 m on shallow or argillic (clayey) soils. It differs from A. arbuscula ssp. arbuscula in its long floral stalks and large leaves. Morphological, chemical, ecological, and cytological data suggest that it is of hybrid origin. It is hexaploid (6x). We hypothesize that 2x A. arbusucla ssp. arbusucla and 4x A. tridentata ssp. wyomingensis are its parents.     

Montia linearis (Portulacaceae): a new record for Utah

Montia linearis Dougl., a plant known from British Columbia to Montana, Nevada, and California, is reported from Utah.     

A new species of Hydropsyche (Trichoptera: Hydropsychidae) from Utah

Hydropsyche quitchupaha, n. sp. , is described and illustrated based on 3 males collected in Sevier, Emery, and Kane counties, Utah. The upturned posteromesal lobes of tergum X, subapically swollen phallobase, and dorsally depressed phallus apex separate this species from all other members of the Hydropsyche scalaris Group.     

A new perennial species of Gilia (Polemoniaceae) from Utah

Gilia tenuis Smith & Neese is a previously undescribed species from Emery and Sevier counties, Utah, apparently closely related to G. caespitosa Gray and G. subnuda Torr. ex Gray. It is distinguished from these species by its possession of a combination of characters including perennial, multicipital habit, lobed basal leaves, and small, pale blue flowers.     

A new species of Rhopalomyia (Diptera: Cecidomyiidae) from Artemisia ludoviciana Nuttall (Compositae) in Utah

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Rhopalomyia (Diarthronomyia) subhumilis Gagné, a new species of Artemisia ludoviciana Nuttall (Compositae), is described and its taxonomically important structural features illustrated. The new species is compared to its most similar North American congeners.          

A new species of Frasera (Gentianaceae) from Uinta Basin, Utah

Frasera ackermanae, sp. nov. is described based on specimens collected from the Brush Creek drainage, Uinta Basin in Uintah County, Utah. The short stem, compact inflorescence, and longer calyx lobes separate this species from the similar Frasera pahutensis Reveal.