Viola nuttallii

Abstract: We examined herbivore damage in a natural association in order to evaluate the hypothesis that herbivory is generally greater in the shade (Maiorana 1981). Damage was measured in relation to habitat, adult plant distribution, and plant size for 13 species of native herbaceous forbs that cross the natural shade/sun ecotone at the interface of montane meadow and aspen (Populus tremuloides) woodland. Eight of the 13 species had statistically significant differences in leaf area damaged between sun and shade individuals (p<0.05). Only 3 of those were more damaged in shade (Aquilegia coerulea, Epilobium angustifolium, and Galium biflorum), while six were more damaged in the sun (Delphinium nelsoni, Helianthella quinquenervis, Lupinus argenteus, Thalictrum fendleri, and Vicia americana). No pattern was detected for 5: Erigeron speciosus, Fragaria ovalis, Lathyrus leucanthus, Viguiera multiflora, and Viola nuttallii. Levels of herbivory were species-specific rather than habitat-related. Thus, the shade habitat hypothesis must be rejected for our system, and the null hypothesis accepted for this natural assemblage. Herbivory within the shade was generally related to plant and leaf size. Two equally common community level patterns of loss occurred in relation to plant distribution. These were: 1. frequency-related, where herbivory was higher in the habitat of highest adult plant occurrence, and 2. inversely-related, where herbivory was higher in the habitat where plants were less common.

Abstract: Morphological, cytological, and phytochemical data were incorporated into numerical and statistical analyses to produce a revision of Viola subsection Nuttallianae. A basic chromosome number of x =...

Abstract: From September 1, 1928, to July 30, 1930, the writer had under observation a small area of level waste land within the city limits of Aurora, Colorado. The Desert Horned Lark (Otocoris alpestris leucolaema) was found here throughout the year. Four nests of this bird were found in the spring and summer of 1929, and one in the spring of 1930. Some observations made upon the birds are thought to be worth recording. The area concerned was rectangular in shape, extending 700 yards north and south by 500 yards east and west. It was bordered on the south by Montview Boulevard, a busy thoroughfare running from Aurora west through the adjacent city of Denver. In the east-central part of the area was a small colony of prairie-dogs (Cynomys ludovicianus) numbering about eight individuals. The Environment.-The Horned Lark is closely associated with the plant life of the environmerit in which it lives. Therefore the following notes on the vegetation of the area are presented. The nomenclature used is that of Coulter and Nelson's New Manual of Rocky Mountain Botany. The identifications have been checked from material in the herbarium of the University of Wyoming. Common names are not available for many of the species, so none is given. The short-grass association covered most of the north and central portions of the territory, about 70 per cent of the ground. This is the principal association throughout the range of the bird studied. It prefers this for roosting and nesting. The dominant species were grama grass (Bouteloua oligostachya) and slender fescuegrass (Festuca octoflora). Subdominant species were Muhlenbergia gracillima, Chrysothamnus plattensis, Opuntia polyacantha, and Gutierrezia sarothrae. Less frequent species were Allium nuttallii, Leucocrinum montanum, Buchloe dactyloides, Viola nuttallii, Lepidium apetalumn, Hedeoma hispida, Plantago purshii, Gaura coccinea, Aristida longiseta, Erysimum asperum, Phellopterus montanus, Eriogonum effusum, and Gilia micrantha. There were also on bare ground two species of low moss and two species of lichens. Leaves of Bouteloua oligostachya comprised 60 per cent or more of the material in each nest. The ruderal association occurred on ground that recently had been cultivated, in an old yard and along the road in the southern end and in the northwest corner. This type of vegetation covered about 10 per cent of the area in all. Here the larks preferred to feed, for it provided many seeds in the winter and supported much insect life in the summer. The young larks were often escorted here on account of food and better protection while yet unable to fly. Different plant species were dominant in different parts of the association. These were Helianthus annuus, H. petiolaris, Iva xanthifolia, and Salsola pestifer. Subdominant species were Bromus tectorum, Sitanion elymnoides, Chaetochloa viridis, Schedonnardus paniculatus, Poa pratensis, Kochia scoparia, and Chenopodium album. Less frequent species were Amaranthus retroflexus, A. blitoides, Lappula erecta, Norta altissimna, Malvastrum coccineum, Sophia pinnata, Cryptanthe crassisepala, Aster hebecladus, Artemisia aromatica, and Centaurea picris. The wheat-grass association was found in irregular scattered patches in the western and southern parts of the territory. In the winter the grass dies down, leaving open bare ground with many small depressions between the tufts in which

Abstract: -Field tests quantifying the behavioral responses of ants to the seeds of twenty Rocky Mountain species were conducted in Gunnison County, Colorado. The results indicate that Claytonia lanceolata Pursh, Corydalis aurea Willd., C. caseana A. Gray., Delphinium nelsoni Greene, and Viola nuttallii Pursh are myrmecochores. The seeds of these species all bear a conspicuous elaiosome and are selectively removed by three species of ants, Formica podzolica Francoeur, Formica canadensis Francoeur, and Myrmica discontinua Weber. These are the first records of ant dispersal from the Rocky Mountains. Comparatively little is known about the ant dispersed (myrmecochorous) plant species of the western United States. Scattered reports suggest that they may be common in some areas, particularly the arid south-west (Berg, 1966; Bullock, 1974; O'Dowd and Hay, 1980; Nesom, 1981) and the moist north-west (Nordhagen, 1959; Berg, 1972). Almost nothing is known about ant dispersal in the Rocky Mountains. Sernander (1906) reported that between 6% and 13% of herbaceous species at high altitudes in Sweden, the French Alps and the north Tyrol were ant dispersed, and speculated that a similar proportion of species might be ant-dispersed in other mountainous regions of the world. Preliminary field experiments with the seeds of Viola nuttallii Pursh strongly suggested that this species is myrmecochorous. This paper reports new information on seed disperal by ants of this and other species. MATERIALS AND METHODS.-The two study sites were located in Gunnison County, in west-central Colorado. One was at an altitude of approximately 3,024m, near the Rocky Mountain Biological Laboratory at Gothic. This is a dry, rocky, subalpine meadow. Areas of little ground cover were mixed with areas of dense vegetation dominated by grasses and false hellebore (Veratrum californicum Durand). There were also small stands of willow (Salix, sp.) and aspen (Populus tremuloides Michx.). The other site was on a steep roadcut near Crested Butte, at an altitude of 2,719m. Vegetation on this site was very sparse and dominated by Corydalis aurea, weeds, and a few grasses. The method for evaluating myrmecochory in a species is detailed in Beattie and Culver (1981) and utilizes both morphological and behavioral criteria. Since ants carry many kinds of objects back to their nests, we looked for morphological adaptations of the seeds which indicate myrmecochory, and specific behavioral responses on the part of the ants. Behavioral responses of undisturbed ant foragers were quantified by the use of bioassays of fresh seeds, in the habitat where the plants were growing. Clumps of five seeds were placed at random in the habitat and observed for periods of up to one hour. Each bioassay was replicated as many times as the supply of fresh material would allow. The responses of ants were classified as follows: ignore-the ant passed close enough to the seed to detect it but exhibited no response at all; antennate-the ant examined the seed with its antennae; pick-up-the ant iesponded by rolling the seed and attempting to pick it up, but the response was not sufficiently intense for the ant to carry it away; remove-the ant removed the seed at least 10 cm. In most cases, an ant which removed a seed 10 cm actually continued to carry it back to the nest. RESULTS.-We bioassayed the seeds of twenty species belonging to fifteen families (Table 1). There was no interaction between ants and the seeds of This content downloaded from 207.46.13.180 on Thu, 08 Sep 2016 06:26:21 UTC All use subject to http://about.jstor.org/terms The Southwestern Naturalist TABLE 1.-Species bioassayed (species marked by an asterisk were ignored in all bioassays). Boraginaceae Mertensia fusiformis Greene Compositae Agoseris aurantiaca (Hook). Greene* Senecio interregemus Nutt.* Taraxacum officinale Wiggars* Cyperaceae Carex egglestonii Mack.* Fumariaceae Corydalis aurea Willd. C. caseana A. Gray Graminae Melica spectabilis Scribn.* Poa interior Rydb.* Hydrophyllaceae Hydrophyllum capitatum Dougl. ex Benth.* Liliaceae Erythronium grandiflorum Pursh Onagraceae Epilobium minutum Lindl. ex Hook.* Polemoniaceae Collomia linearis Nutt.*