Gray Var Research Articles

Plate 346. Choisya dumosa var. arizonica

The history, taxonomy, distribution, habitat and cultivation of Choisya dumosa (Torr.) A. Gray var. arizonica (Standley) L. Benson (Rutaceae), a shrub native to the south‐western United States, are discussed; a botanical description and illustrations are also provided. Choisya ternata Kunth and its cultivar Sundance® are also considered, as is ‘Aztec Pearl’, a hybrid between C. ternata and C. dumosa var. arizonica.

Reaction of Select Tepary Bean to Ashy Stem Blight and Fusarium Wilt

Cultivated tepary bean (Phaseolus acutifolius A. Gray var. latifolius Freeman) has received considerable interest as a crop for dryland production regions around the world. Successful tepary bean production will depend partly upon its resistance to endemic diseases. Thirteen select tepary bean lines were evaluated in the field and by rice-seed inoculation for resistance to ashy stem blight [Macrophomina phaseolina (Tassi) Goid.] and by a root-clip inoculation method for resistance to fusarium wilt [Fusarium oxysporum Schlechtend.:Fr. f. sp. phaseoli J.B. Kendrick and W.C. Synder) (Fop)]. Three lines, Mex-114, PI 440806-s, and PI 321637-s, exhibited high levels of resistance to both pathogens and their diseases. These reactions, combined with known resistances to other pathogens, will allow identification of multiple-disease-resistant tepary bean germplasm for use in different production regions and breeding programs.

Incomplete Dominance of Rust Resistance in Tepary Bean

Foliar diseases are a major constraint to cultivated tepary bean (Phaseolus acutifolius A. Gray var. latifolius Freeman) production in some environments. The reactions of 12 cultivated teparies to eight individual races (41, 47, 49, 51, 53, 58, 67, and 73) of the bean rust fungus Uromyces appendiculatus (Pers.) Unger var. appendiculatus maintained at Beltsville, Md., were examined under greenhouse conditions. These diverse races, used together, overcome all of the major rust-resistance genes present within the 19 host differential cultivars of common bean (Phaseolus vulgaris L.). Seven lines (GN-605-s, GN-610-s, PI 321638-s, PI 502217-s, Neb-T-6-s, Neb-T-8a-s, and Neb-T-15-s) exhibited similarly high levels of resistance (immunity or necrotic spots without sporulation) to all eight races. Inheritance of resistance was examined across five susceptible × resistant (S × R) and three resistant × resistant (R × R) populations. The rust reactions in the F1, F2, and F3 generations derived from S × R crosses revealed that the immune or necrotic resistance response was conditioned by a single locus exhibiting incomplete dominance. The rust resistance of four lines tested for allelism in R × R crosses was found to be derived from the same gene. This apparent lack of variability for rust resistance suggests that a single introgression event may realize the full potential for cultivated tepary bean to contribute rust resistance to common bean through interspecific hybridization. In addition, the limited variability for resistance to the highly variable rust pathogen in cultivated tepary bean supports the occurrence of a “bottleneck effect” during domestication of this species, as observed in germplasm diversity studies.

Incomplete Dominance of Rust Resistance in Tepary Bean

Foliar diseases are a major constraint to cultivated tepary bean (Phaseolus acutifolius A. Gray var. latifolius Freeman) production in some environments. The reactions of 12 cultivated teparies to eight individual races (41, 47, 49, 51, 53, 58, 67, and 73) of the bean rust fungus Uromyces appendiculatus (Pers.) Unger var. appendiculatus maintained at Beltsville, Md., were examined under greenhouse conditions. These diverse races, used together, overcome all of the major rust-resistance genes present within the 19 host differential cultivars of common bean (Phaseolus vulgaris L.). Seven lines (GN-605-s, GN-610-s, PI 321638-s, PI 502217-s, Neb-T-6-s, Neb-T-8a-s, and Neb-T-15-s) exhibited similarly high levels of resistance (immunity or necrotic spots without sporulation) to all eight races. Inheritance of resistance was examined across five susceptible × resistant (S × R) and three resistant × resistant (R × R) populations. The rust reactions in the F1, F2, and F3 generations derived from S × R crosses revealed that the immune or necrotic resistance response was conditioned by a single locus exhibiting incomplete dominance. The rust resistance of four lines tested for allelism in R × R crosses was found to be derived from the same gene. This apparent lack of variability for rust resistance suggests that a single introgression event may realize the full potential for cultivated tepary bean to contribute rust resistance to common bean through interspecific hybridization. In addition, the limited variability for resistance to the highly variable rust pathogen in cultivated tepary bean supports the occurrence of a “bottleneck effect” during domestication of this species, as observed in germplasm diversity studies.

Dos novedades en Zinnia subgénero Diplothrix (Compositae: Heliantheae) del centro de México

Se describen como nuevas a Zinnia acerosa (DC.) A. Gray var. guanajuatensis y a Z. zamudiana de los estados de Guanajuato y Querétaro respectivamente. La primera difiere de la variedad típica en el hábito rastrero, en las cabezuelas más anchas y con mayor cantidad de flores, así como en aquenios casi completamente carentes de vilano. La segunda parece estar emparentada con Z. juniperifolia (DC.) A. Gray, de la que se distingue de manera notable en el hábito rastrero, más o menos almohadillado, en las cabezuelas sésiles o muy cortamente pedunculadas, al igual que en las lígulas que son conspicuamente más pequeñas y de color menos intenso.

Reaction of Select Tepary Bean to Bean Golden Mosaic Virus

Cultivated tepary bean (Phaseolus acutifolius A. Gray var. latifolius Freeman) has potential for production during the hot, dry seasons in the tropics. Bean golden mosaic virus (BGMV), however, seriously limits production of Phaseolus spp. in such environments. Twelve select tepary beans were evaluated for reaction to BGMV across four field nurseries near Isabela, Puerto Rico. Disease reaction was principally determined by measurement of seed yield (kg·ha–1) and weight (g 100/seeds). All tepary beans possessed some tolerance to BGMV, as they produced comparatively moderate seed yield despite expression of severe foliar yellow mosaic symptoms. On average, tepary bean yielded 133% of the BGMV-resistant dry bean (Phaseolus vulgaris L.) control `Dorado'. Four teparies, Neb-T-6-s, GN-610-s, Neb-T-8a-s, and PI 321637-s, expressed superior tolerance to BGMV as they yielded above the trial mean in at least three of four trials. Harvested seed quality was uniformly poor across all lines, averaging 18% less weight than in the non-BGMV trials. The combination of the observed tolerance with escape mechanisms and cultural disease control practices may enable production of tepary bean in regions and seasons that experience moderate to severe BGMV epidemics.

Hybridization in the Catalina Island Mountain Mahogany (Cercocarpus traskiae): RAPD Evidence

The Catalina Island mountain mahogany is one of 10 species of shrubs and small trees (Lis 1992) comprising the genus Cercocarpus H. B. K (Rosaceae). Species in the genus are widely distributed throughout western North America and are delimited primarily on the basis of leaf characteristics (Mortenson 1973; Lis 1992). The Catalina Island mountain mahogany (C. traskiae Eastwood) is one of the most distinctive species in the genus due to its thick, coriaceous leaves and woolly pubescence on the leaf undersurface. The species is extremely rare, restricted to Wild Boar Gully on the southwest side of Santa Catalina Island in the Channel Islands off the coast of California (Fig. 1). When the population was first discovered in 1897, it consisted of over 40 individuals (Thorne 1967). Due to overgrazing by introduced mammalian herbivores (Coblentz 1980; Hobbs 1980), however, the population has been greatly reduced (Rieseberg et al. 1989). Cercocarpus traskiae is listed as endangered by the state of California and thus is afforded protection by California law (Smith & Berg 1988). Inexplicably, the species is not listed as endangered or threatened by the U.S. Fish and Wildlife Service, although it is under consideration for listing. In the late 1970s a detailed inventory of the Wild Boar Gully population was undertaken, and a total of eight Cercocarpus trees were discovered and tagged (Martin 1984). In addition, two of the trees (A, B; Fig. 1) were fenced to protect them from herbivores, and in 1985 the Catalina Conservancy constructed a larger fence around an area that included both trees, as well as about an acre of good habitat. The fencing effort was extremely successful, and by 1988 approximately 70 seedlings were observed within the fenced area (Rieseberg et al. 1989). Unfortunately, several of the adult plants resembled the island mountain mahogany, Cercocarpus betuloides Torrey & A. Gray var. blancbeae (C. Schneider) Little, in key morphological features such as leaf pubescence and leaf thickness or were immediate for these characters (descriptions of both species are given by R. Lis in Hickman [1993]). Cercocarpus betuloides var. blancbeae is only slightly more widespread than C traskiae, occurring on all of the Channel Islands except San Clemente. But the species is much more abundant than C traskiae on Santa Catalina and is known to occur in adjacent canyons, so the possibility of hybridization between the two species could not be dismissed. Furthermore, it is suspected that some of the seedlings might be of hybrid origin (T. Martin, personal communication). In an attempt to clarify the identity of morphologically ambiguous individuals, Rieseberg et al. (1989) undertook a study of allozymic variation and leaf anatomy of all the adult mahogany trees discovered in Wild Boar Gully. Of the eight adult trees in the Gully, three were anatomically intermediate between C. traskiae and C betuloides var. blancbeae, suggestive of hybridization. Analysis of 17 isozyme loci in C traskiae, as well as a nearby population of C betuloides var. blancbeae (Fig. 1), revealed one diagnostic isozyme polymorphism differentiating the two species. Based on this single isozyme polymorphism, five of the eight trees were diagnosed as C traskiae, one as C betuloides var. blancbeae, and two as hybrids. However, isozyme analyses of the 28 seedlings large enough to survive the loss of a single leaf revealed all to be pure C traskiae. The results from this study were not entirely satisfactory, however, because the classification of individuals as parental versus hybrid was based on a single locus. The use of a single diagnostic locus can ensure the correct identification of first-generation hybrids, but F2or later-generation hybrid or backcross progeny could easily be misdiagnosed as belonging to one of the parental classes. Thus, it was not surprising that two of the plants lacking a hybrid enzyme genotype were anatomically Paper submitted April 1994; revised manuscript accepted July 15, 1994.

Field Performance of Select Tepary Bean Germplasm in the Tropics

Dry edible bean (Phaseolus vulgaris L.), a staple food crop for many tropical countries, is not well adapted to the hot temperatures and low rainfall that prevail during the dry seasons. Cultivated tepary bean (Phaseolus acutifolius A. Gray var. latifolius Freeman), an edible small‐seeded desert annual with extreme tolerance to drought, may be suited to dry‐season production in the tropics. To test this hypothesis, production potential of select cultivated tepary bean germplasm was evaluated in different tropical environments and compared to dry bean. Eleven lines (Neb‐T‐l‐s, Neb‐T‐6‐s, Neb‐T‐Sa‐s, Neb‐T‐15‐s, GN‐605‐s, GN‐610‐s, Pls 321637‐s, 321638‐s, 440788‐s, 440806‐s, and 502217‐s) were field tested from 1989 to 1993 in six trials, two each at Isabela and Fortuna, Puerto Rico, and El Zamorano, Honduras. Locally adapted, high‐yielding dry bean checks included in some trials in Puerto Rico were ‘Dorado’ and ‘Arroyo Loro’. Tepary lines yielded 70% of Dorado in the warm environment of lsabela and 170% of Dorado and Arroyo Loro in the hot environment of Fortuna. Tepary seed weight averaged 30% less than the dry bean cheeks. Seed protein concentration of tepary bean averaged 12% less than Dorado, and the seed protein concentration was inversely related to yield (r − 0.70*). Tepary bean proanthocyanidin (condensed tannin) concentration, an antinutritional factor, was 73% less than Dorado. The tepary bean lines have potential for dry‐season production in the tropics where dry bean traditionally yields poorly.

Description of a Rare New Cliff-Dwelling Species from Kaua'i, Schiedea attenuata (Caryophyllaceae)

A new species of Schiedea is described and illustrated. It is restricted to the sheer Kalalau cliffs on the island of Kaua'i, the oldest main island of the Hawaiian Islands. It is most closely related to the sea-cliff species S. globosa H. Mann from O'ahu, Moloka'i, and Maui. Recent collecting activities in the Hawaiian Islands by Kenneth R. Wood for his own investigations of Kaua'i and for the Hawaii Plant Conservation Center of the National Tropical Botanical Garden, especially rappelling the vast cliffs of Kalalau Valley, Kaua'i, have yielded more than a dozen new species since the publication of the Manual of the Flowering Plants of Hawai'i (Wagner et al., 1990). Wood collected a highly distinctive new species of Schiedea Chamisso & Schlechtendal on one of these rappels. This species, described herein as Schiedea attenuata W. L. Wagner et al., is characterized by glossy, succulent, long-attenuate leaves, a short, relatively open inflorescence, perfect flowers with recurved nectary shafts, and 5-6(7) carpels. It has been collected twice on rappels into Kalalau Valley on the Kalahu side below and west of the first lookout (southwesternmost) at 700-800 m. Although the diverse mesic cliff plant communities on the upper Kalalau Valley north-facing cliffs are outstanding assemblages of rare species, fewer than 20 individuals of this new species were noted by Wood during his extensive investigations. The southwestern corner of the upper Kalalau Valley has habitats that may harbor additional populations of this rare species. Plants grown from seed are currently under cultivation in the University of California at Irvine greenhouse as part of a collaborative study on the phylogeny and evolution of dioecy in this endemic Hawaiian genus. The extensive Kalalau Valley harbors about 20% of the species of the lineage to which Schiedea belongs, including, in addition to S. attenuata, Alsinidendron lychnoides (Hillebrand) Sherff, Schiedea apokremnos H. St. John, S. membranacea H. St. John, S. nuttallii W. J. Hooker, and S. spergulina A. Gray var. spergulina. Schiedea and Alsinidendron constitute a monophyletic radiation in the Hawaiian Archipelago, based on the presence of highly specialized floral nectaries and the absence of petals in all species. Nectar is collected and presented through a hypodermic-like shaft in Schiedea and at the base of a flapor cuplike structure in Alsinidendron. In a majority of the members of the subfamily Alsinoideae, to which the endemic Hawaiian genera belong (Pax & Hoffmann, 1934; Weller et al., 1990), the nectary is represented by a mound of nectariferous tissue bisected by a lateral furrow located on the abaxial side of each antesepalous stamen (Thomson, 1942). Ontogenetic studies indicate that the nectary differences between Schiedea and Alsinidendron represent changes in homologous structures (E. Harris and Wagner, unpublished obs.). A preliminary phylogenetic analysis by us suggests that Schiedea attenuata is the sister species of the most widespread species, S. globosa H. Mann, a sea-cliff species found on O'ahu, Moloka'i, and Maui. Both of these species share the derived characters of succulent leaves, recurved nectary shafts, and more styles than the typical three found in most Schiedea species. Schiedea globosa differs in possessing a specialized dense globose inflorescence, a subdioecious breeding system, and a more sprawling habit. The phylogenetic analysis suggests that the hermaphroditic condition of S. attenuata may be secondarily derived. Schiedea attenuata W. L. Wagner, Weller & Sakai, sp. nov. TYPE: Hawaiian Islands. Kaua'i: Hanalei District, Kalalau rim, Kalahu side below and W of first Kalalau lookout, 300 m E of plane crash [site], [22?8'N, 159?39'W, NW NOVON 4: 187-190. 1994. This content downloaded from 157.55.39.138 on Thu, 19 May 2016 05:11:35 UTC All use subject to http://about.jstor.org/terms

Microbial N and biomass, respiration and N mineralization in soils beneath two chaparral species along a fire-induced age gradient

A decline in available nutrients may contribute to the loss of vigor observed in older chaparral stands. We examined N mineralization and the storage of C and N in the microbial biomass of soil along a fire-induced chaparral chronosequence in San Diego County, Calif. Soil was collected under chamise (Adenostoma fasciculatum H. & A.) and ceanothus [ Ceanothus greggii Gray var. perplexans (Trel.) Jeps] shrubs in stands burned 0, 2, 4, 11, 20, 54 and 80 yr prior to the study. Soil collected from the top 5 cm beneath chamise and ceanothus had similar microbial biomass patterns with stand aging. The amount of microbial C in soil remained relatively constant across the age gradient. Concentrations of microbial N and the amount of N mineralized fluctuated, with no significant trend across the stand-age gradient. For both chaparral species, NH 4 + concentrations in soil were significantly higher in the recently burned stand (age = 0) than in stands burned from 2 to 80 yr earlier. Ammonium and nitrate concentrations in soil were not significantly different in most instances among soils from 2 to 80 yr-old stands. Soil collected under A. fasciculatum had significantly higher respiration rates, and higher concentrations of NH 4 + and NO 3 − compared to C. greggii, suggesting that these chaparral species have differential influences on microbial processes in the soil around them.

Leaf Gas Exchange in Water‐Stressed Common Bean and Tepary Bean

Tepary bean, Phaseolus acutifolius A. Gray var. latifolius G. Freeman, is adapted to hot arid conditions and might be a valuable source of genes to improve the drought tolerance of P. vulgaris L. We tested the hypothesis that P. acutifolius adaptation to arid environments relies on differences in gas exchange characteristics leading to greater water‐use efficiency. Both species were subjected to controlled levels of water stress by enclosing the root systems in semipermeable membranes immersed in nutrient solutions osmotically adjusted with polyethylene glycol. Phaseolus acutifolius had higher net photosynthetic rates (Pn) than P. vulgaris at high to moderately low water potentials. The Pn rates of P. acutifolius declined more rapidly with lower water potential than those of P. vulgaris. This response was related to increased stomatal closure with decreased water potential. Higher Pn, rates at any given internal CO2 partial pressure (C1) led to higher water‐use efficiency in P. acutifolius than in P. vulgaris. Analysis of the initial slope of Pn vs. C1, curves indicated that P. acutifolius bad higher carboxylation efficiency (CE) at low C1. In both species, water stress significantly reduced light‐ and CO2‐saturated Pn rates and only slightly lowered the CE. Similar mesophyll palisade surface area in P. acutifolius and P. vulgaris suggested that differences in Pn rates at low C1 might be related to biochemical rather than anatomical leaf characteristics. Higher water‐use efficiency at moderate water deficits may contribute to P. acutifolius adaptation to arid environments.

Saturated Rates of Photosysnthesis in Water‐Stressed Leaves of Common Bean and Tepary Bean

The tepary bean, Phaseolus acutifolius A. Gray var. latifolius G. Freeman, is adapted to arid conditions and is a potential source of genes to improve the drought tolerance of common bean, P. vuigaris (L.). The mechanisms of drought tolerance in P. acutifolius are still unclear. Light and CO2 saturated rates of photosynthetic O2 evolution (Pn) measured in a Hansatech leaf‐disk chamber and roomtemperature chlorophyll fluorescence transients at 740 nm were used to assess the mesophyll tolerance to dehydration. Detached P. acntifolius leaves maintained higher relative water contents (RWC) and water potentials that those of P. vulgaris. Rapidly dehydrated leaves from both species showed identical responses of their saturated rates of photosynthesis to RWC changes. Mesophyll photosynthetic capacity was very toleranto dehydration even at water deficits known to cause severe reduction of CO2 assimilation. Similar results were obtained with samples taken from plants acclimated to water‐deficit stress. Apparent quantum yield of photosynthetic O2 evolution and variable fluorescence suggest that the slow Pn decline with dehydration was not related to an inhibition of photosynthetic electron transport. These results indicate that genotypic variability in drought tolerance between P. vulgaris and P. acutifolius is not related to differences in mesophyll tolerance to dehydration. P. acutifolius adaptation to an arid environment relies more on dehydration postponement than on tolerance.

Tolerance of Tepary and Navy Beans to NaCl During Germination and Emergence

Seeds of two tepary bean lines (Phaseolus acutifolius Gray var. latifolius) and one navy bean cultivar (P. vulgaris L. `Fleetwood') were tested with 0.0-, – 0.3-, –0.6-, -0.9-, -1.2-, or – 1.5-MPa NaCl solutions to determine their relative salt tolerance during germination and emergence. Developmental stage was not affected at – 0.3 MPa, but with salinities more negative than -0.9 MPa, `Fleetwood' developed more slowly than the tepary lines; no plants emerged at – 1.5 MPa. Teparies tended to maintain higher water and osmotic potentials than navy over the range of NaCl concentrations used, although turgor was similar for all three genotypes. Leaf area was reduced more in navy than in white tepary at – 0.6 and – 0.9 MPa. Dry weights of navy were higher than those of either tepary bean at all NaCl concentrations, although decreases at higher salinities relative to 0.0 MPa were greater for navy than for teparies. Root: shoot ratios were higher at – 0.3 MPa than at 0.0 MPa, but were lower at the higher NaCl concentrations for all three genotypes. Overall, tepary beans tolerated NaCl better than navy. The characteristic that best indicated differences in salt tolerance was developmental stage.

Germination Response of Tepary and Navy Beans to Sodium Chloride and Temperature

Abstract White and brown accessions of tepary bean (Phaseolus acutifolius Gray var. latifolius) and navy bean (Phaseolus vulgaris L. ‘Fleetwood’) were germinated at 0.0, −0.5, −1.0, −1.5, −2.0, and −2.5 MPa of NaCl at 25 or 35C for 9 days. Differences in germination percentages and rates between the two species were significant, especially at the higher salt concentrations. At 25C and salinities greater than or equal to − 2.0 MPa, tepary accessions had significantly higher percentage germination and germination rates than navy. At 35C this difference was noted at −1.5 MPa. The fresh weights of root plus hypocotyl appeared lower than controls at even the lowest concentration of salinity (− 0.5 MPa), suggesting that seeds germinated with NaCl did not produce vigorous seedlings. Of the three beans tested, the two tepary beans were more tolerant to NaCl than the navy bean, with the white tepary being most tolerant.

Effects of water stress on the water relations of Phaseolus vulgaris and the drought resistant Phaseolus acutifolius

The tepary bean (Phaseolus acutifolius Gray var. latifolius), a drought resistant species, was compared under water stress conditions with the more drought susceptible P. vulgaris L. cvs Pinto and White Half Runner (WHR). In order to better understand the basis for the superior drought resistance of tepary, this study was designed to determine the relationships among leaf water potential, osmotic potential, turgor potential, and relative water content (RWC).Plants were prestressed by withholding irrigation water. These stress pretreatments changed the relation between leaf water potential and relative water content of both species so that prestressed plants had lower water potentials than controls at the same leaf RWC. Tepary had lower water potentials at given RWC levels than Pinto or WHR; this can account for part of the superior resistance of tepary. In all genotypes, prestressed plants maintained osmotic potentials approximately 0.2 MPa lower than controls. Tepary reached osmotic potentials that were significantly lower (0.15 to 0.25 MPa) than Pinto or WHR. Both control and prestressed tepary plants had 0.05 to 0.25 MPa more turgor than Pinto or WHR at RWC values between 65 and 80%. Both prestressed and control tepary plants had greater elasticity (a lower elastic modulus) than Pinto or WHR. This greater turgor of tepary at low RWC values could be caused by several factors including greater tissue elasticity, active accumulation of solutes, or greater solute concentration.Tepary had significantly lower osmotic potentials than the P. vulgaris cultivars, but there was little difference in osmotic potential between Pinto and WHR. Knowledge of differences in osmotic and turgor potentials among and within species could be useful in breeding for drought resistance in Phaseolus.

Effect of 2-(3,4-Dichlorophenoxy)-triethylamine on the Synthensis of cis-Polyisoprene in Guayule Plants (Parthenium argentatum Gray)

The application of 2-(3,4-dichlorophenoxy)-triethylamine to guayule (Parthenium argentatum Gray var 593) plants results in a 2-fold stimulation of rubber synthesis and a 1.5- to 3-fold increase in mevalonic acid kinase, isopentenyl pyrophosphate isomerase, and rubber transferase. The increase in these enzymic activities accounts in part for the chemical induction of rubber synthesis.

Estudios cromosómicos en Lycium (Solanaceae) de Norteamérica

Se presenta la información de los estudios cromosómicos reportados sobre especies de Lycium en todo el mundo. Usando la técnica del "squash" se efectuaron recuentos cromosómicos a partir de células madres del polen en taxa de Lycium norteamericanos y, en un solo caso, se determinó este número utilizando la radícula de una semilla en germinación. Los taxa estudiados fueron: L. andersonii Gray var. andersonii , L. andersonii var. desertícola (C. L. Hitchc.) Jepson, L. andersonii var. pubescens S. Wats., L. andersonii var. wrightii A. Gray, L. berlandieri Dun. var. berlandieri, L. berlandieri var. Parviflorum (Gray) Terrac., L. berlandieri var. peninsulare ( Brandeg.) C. L. Hitchc., L. brevipes Benth. var. brevipes, L. californicum Nutt. ex Gray var. californicum, L. californicum var. arizonicum A. Gray, L. californicum var. interior Chiang, L. carolinianum var. quadrifidum (Moc. & Sessé ex Dun. ) C. L. Hitchc., L. cooperi A. Gray, L. macrodon A. Gray var. macrodon, L. nodosum var. isthmense ( Chiang) Chiang, L. pallidum Miers var. pallidum, L. parishii A. Gray var. parishii, L. parishii var. modestum (l. M. Johnst.) Chiang, L. puberulum var. berberidoides ( Correll) Chiang y L. torreyi A. Gray. Se encontraron números cromosómicos de n = 12, 24, 48, 60, y 2n = 24. Se concluye que x = 12 es el número cromosómico básico de Lycium. Se discute el origen de n = 18, reportado antes de este estudio.

Hepaticae of Rocky Mountain National Park, Colorado

Thirteen families, 19 genera, 19 species, 6 subspecies, 12 varieties and one forma of hepaticae are reported from Rocky Mountain National Park, north-central Colorado. Lepidozia reptans (L.) Dum., Lophozia obtusa (Lindb.) Evans, L. opacifolia Culm., L. ventricosa var. silvicola (Buch) Jones, Marsupella sphacelata fo. media (Gieseke) Schust. and Riccardia multifida (L.) S. Gray var. multifida are reported new to Colorado. Rocky Mountain National Park is located in the Front Range (which is dominated by Precambrian rocks) of the Rocky Mountains at the Continental Divide in north-central Colorado, and extends from 40'10'-40'43'N to 105'30'-105'55'W. The park is in Boulder, Larimer and Grand counties. There are more than 100 named peaks above 3048 m ele- vation; the mean elevation at the base of the mountain peaks is ca. 2433 m; and the highest elevation is Longs Peak, at 4344 m, located in the southeastern corner of the park. Although Austin (1874, 1875), Rau (1876) and Evans (1915) early reported many liv- erworts for Colorado, none of their collections were made in this park. Frye and Clark (1937-1947) cited the following seven taxa of hepatics for the park from Kiener's collec- tions that were made mainly in the vicinity of Longs Peak in Boulder County: Lophozia alpestris, L. incisa, L. ventricosa, Scapania curta, S. irrigua, S. undulata and S. undulata var. oakesii. Weber (1963) reported Anthelia juratzkana, Gymnomitrion corallioides and Pellia endiviifolia from the park based on his own collections as well as Kiener's collec- tions. Recently, Hermann (1976) reported Lophozia ascendens and Tritomaria exsecti- formis from the park. I have made extensive collecting trips into the park during the summer of 1978 and 1979, visiting especially Estes Park, Longs Peak Campground, Wild Basin and Grand Lake, and have collected over 400 packets of hepaticae. The eastern slopes of the Rocky Mountain National Park are forested mainly by pon- derosa pine (Pinus ponderosa), lodgepole pine (P. contorta), Douglas fir (Pseudotsuga menziesii) and aspen (Populus tremuloides), while the western slopes of the park have lodgepole pine (Pinus contorta), limber pine (P. flexilis), Engelmann spruce (Picea en- gelmannii) and subalpine fir (Abies lasiocarpa). The hepatic flora of the Rocky Mountain National Park is relatively small in spite of the little disturbance by human activities, but the growth of hepatics west of the Continental Divide (where the mountain slopes gently downward) is significantly greater than east of the Divide. Because of the presence of many waterfalls, streams and lake shores, there is a significant number of exceptionally rich microhabitats. Most of the collections cited below have been collected along trails intersecting many small streams in the subalpine region. The present paper is based upon the previously mentioned literature, upon my own collections and upon specimens (mainly Scapania spp.) borrowed from the herbaria of ALA, CANM, COLO, DUKE, F, MICH, TENN and us. The collection numbers are mine unless otherwise indicated. The nomenclature follows Stotler and Crandall-Stotler (1977). Only 007-2745/80/351-354$0.65/0

Growth and Development of Polemonium Foliosissimum on High Elevation Rangeland in Utah

Polemonium foliosissimum A. Gray var. alpinum (Brand) is a perennial forb of high elevation aspen and herbland range. In northern Utah, the annual life cycle is completed within approximately 3 months after snowmelt; stem elongation occurs in June, flowering in July, and seed maturation and dispersal in August. A low temperature stratification treatment to the perennial parts was necessary for the initiation of stem elongation, and subsequent long photoperiods were required for continued growth and flowering. Seed germination was restricted by the copious sheath of mucilage that surrounds wetted seeds; this restriction was largely removed by a 15-min acid scarification treatment. Carbohydrate reserves in the caudex generally increased continuously from the flowering through the seed dispersal stages. Clipping treatments applied for 4 consecutive years at three phenological stages reduced subsequent growth and vigor. Recovery from clipping treatments was slow over an additional 3 years. INTRODUCTION Polemonium foliosissimum A. Gray var. alpinum (Brand), white polemonium, is an important perennial forb of high elevation aspen and herbland range, because of its abundance in localized areas and its palatability to livestock and big game. The species occurs in subalpine areas of the Intermountain States from Idaho to New Mexico and in Colorado. Davidson (1950) considered the species to be a complex of intergrading populations. Using morphological, cytological and chromatographic analyses as his basis, Anway (1968) segregated four varieties (alpinum, flavum, foliosissimum and molte) that overlap in many characters and form continuously varying populations for nearly all characters. Plants of the present study generally agreed in morphology with the characters of variety alpinum, which ranges through the mountains of northern Utah, northeastern Nevada and southwestern Wyoming. STUDY SITEES Studies were conducted in aspen and herbland range on the Mud Creek Sheep Allotment (Uinta National Forest) and Tony Grove Canyon (Cache National Forest), both in northern Utah. The environmental conditions and plant community composition are typical of high elevation sites in this region. Mud Creek was described by Matthews and Conrad (1968) and Tony Grove by Florez (1971). Polemonium is widely distributed, but plant densities are generally low in the study areas; cover values ranged from less than 1 % in aspen 1 The authors were stationed at Logan, Utah, at the Forestry Sciences Laboratory, which is maintained in cooperation with Utah State University,

Hybridization between Members of Polemonium delicatum Ryd. and P. foliosissimum A. Gray var. molle (Greene) Anway in Southern Utah

The presence of a hybrid swarm in Utah between Polemonium delicatum Ryd. and P. foliosissimum A. Gray var. molle (Greene) Anway was determined. Analysis indicated the swarm to be basically bilateral, with the majority of backcrosses being unilateral with P. folzosvisszmum var. molle.