Herbaceous Flowering Plants Research Articles

Canna yellow mottle virus Detected in Canna in Florida

Cannas are herbaceous flowering plants native to the tropics and subtropics and widely cultivated as ornamentals in Florida. Canna yellow mottle virus (CaYMV), previously reported in Japan and Minnesota, is now also present in Florida, based on symptoms, microscopy, PCR, and sequence analysis. There is no known vector for this virus. Canna yellow mottle disease can be an economically important disease constraint on the production of cannas in Florida. Accepted for publication 14 July 2004. Published 9 August 2004.

Distribution of Bryophytes on Subantarctic Heard Island

Heard Island is a small, isolated subantarctic island dominated by an ice covered volcano. Glaciers descend the volcano to the sea. Coastal ice free areas of tundra are present separated from each other by glaciers. Each of these areas can be considered as individual islands and Heard Island an archipelago. The distribution of 49 bryophyte taxa across five major and four minor ice-free areas was examined. Fifty percent of the bryophyte taxa exhibited widespread distribution, occurring on all ice-free islands examined. Absence of some conspicuous species from particular areas appeared to reflect situations where limited habitat variation has restricted the establishment of species. With present global warming, glacial retreat on Heard Island is rapid. Consequently, areas suitable for colonization by plants are increasing and previously separated ice free areas are now merging. This study provides baseline data against which future studies will be able to investigate possible changes in bryophyte species diversity and distribution on Heard Island. Subantarctic Heard Island (53?05'S, 73030'E) is approximately 4,850 km SE of southern Africa, 4,350 km SW of Western Australia and 1,650 km N of the Antarctic continent. The island is an emergent portion of a mid-ocean ridge with a mixed geology of pelagic limestones and volcanics (Clarke et al. 1983). A large active volcano 2,475 m in elevation and 20 km in diameter dominates the landscape (Figs. 1, 2a). Heard Island is 42 km long and has a surface area of 385 km2. Glaciation on Heard Island may have occurred as early as the Miocene (Quilty et al. 1983) and the island's position south of the oceanic Antarctic Convergence would have ensured major glaciation events during cool episodes of the Pleistocene. Today, Heard Island is severely glaciated and has been continuously since the Last Glacial Maximum (approximately 18,000 years ago, Climap 1976). Allison and Keage (1986) estimated that in 1980 approximately 80% of Heard Island was ice covered, with glaciers descending from 2,400 m to sea level. Ice free areas are coastal and rarely exceed 400 m in elevation. As tidewater glaciers separate these ice-free areas from one another, the ice free areas can be considered analogous to individual islands, and Heard Island analogous to an archipelago. With current climate warming, glacial retreat is occurring rapidly (Scott 1990), with some ice-free areas coalescing. Heard Island has a remarkably constant temperature regime both diurnally and yearly, moderated by the surrounding ocean. Mean annual temperature is 1.2 oC, with a seasonal range of 4.5 oC. Rain or snow falls on most days of the year and the island is severely battered by wind storms, mostly from NW to SW directions (Allison & Keage 1986). Approximately 5% or 20 km2 of the total surface area of Heard Island is covered by substantial vegetation. Herbaceous flowering plants and bryophytes are the major components of the vegetation. The flora is small, with only 11 flowering plant species and 58 bryophyte species recorded from the island (Bergstrom 1993; Bergstrom & Seppelt 1988; Scott 1989). Much of the coastal ice-free areas are covered by some of the most extensive angiosperm cushion vegetation on Earth. Bergstrom (1993), Hughes (1987), Jenkin (1980), Whinam (1989) have examined the vegetation on the island. Bergstrom (1993) identified five major vegetation types which are summarized and illustrated in Table 2 and Fig. 2. Continua and variations within the vegetation types can be found. Bryophytes are a major component of many of the vegetation types and in many cases, such as in closed bryophyte vegetation on shallow stable ground (Fig. 2E), are the dominant component. The geological history of the island necessitates that all members of the biota reached the island via some form of long distance, trans-oceanic dispersal. Bergstrom and Seppelt (1988) identified five phytogeographical elements amongst moss species from the island. These were species restricted to the subantarctic, species found in southern South America and subantarctic islands, southern hemi0007-2745/97/349-355$0.85/0 This content downloaded from 157.55.39.6 on Mon, 19 Sep 2016 05:53:17 UTC All use subject to http://about.jstor.org/terms 350 THE BRYOLOGIST [VOL. 100 I I I 731 5'E 73.30'E 73A45'E

On a color change from yellow to red in the floral tissues of a dyer's saffron cultivar

Summary By using a spot scanning technique, the color change from yellow to red manifested in the floral tissues of Mogami-Benibana, a cultivar of dyer's saffron ( Carthamus tinctorius L.), was investigated. Stamens and pistils were separated from fresh florets of the herbaceous flowering plant for microscopic observation of the zones of red color development. In pistils, color change is localized in the stigma and the peripheral region of the stylar canal. Observations of the fibrovascular bundle are especially indicative that the pollination process coincides with induction of the red shift. GA 3 was found to be a stimulator of tissue reddening, while IAA showed no effect. All red products isolated from the test samples were identical with authentic carthamine.

Meristem Allocation: A New Classification Theory for Adaptive Strategies in Herbaceous Plants

A major goal in studies of evolutionary ecology has been to define a classification of adaptive strategies that can be used for interpreting variation in fitness within species and patterns of diversity and species coexistence within and between habitats. An adaptive strategy is often associated with a particular pattern of allocation (e.g. of a limiting resource) that maximizes fitness in a given environment (Solbrig 1994). Different allocation patterns are assumed to be a consequence of tradeoffs between life history traits resulting from certain constraints (Stearns 1992). Hence, organisms may exhibit sets of traits that are predictably related to their ecology (Grime et al. 1988). Virtually all adaptive strategy theories based on allocation patterns in plants define strategies in terms of biomass allocation. A number of life history traits have been quantified in this way. The most common of these involves biomass allocation to reproductive versus vegetative functions (i.e. reproductive effort) (Hancock and Pritts 1987, Wilson and Thompson 1989, Bazzaz and Ackerly 1992). Biomass allocation to above versus below ground structures (Tilman 1988) and to growth, reproduction, structure, and defence (Taylor et al. 1990) have also been used to identify adaptive strategies in plants. Watson (1984) traces the roots of biomass allocation in life history strategies to the animal ecology literature (e.g. Cody 1966). Extending the use of biomass allocation to plant strategy theories seems to have arisen from convenience and established precedent in animal studies (Watson 1984). However, the use of biomass in allocation measures has a number of limitations. Problems have been most widely noted in studies of reproductive effort in plants. Partitioning biomass to reproductive and vegetative functions is difficult when support structures that are essential to, but not directly involved in reproduction, are considered. This is especially difficult when these structures have photosynthetic capability (a vegetative function) (Reekie and Bazzaz 1987a, Bazzaz and Ackerly 1992). Studies of biomass allocation also assume that there is one resource (i.e. carbon) that limits both growth and reproduction. However, different resources may limit growth in different environments and at different times in a plant's life (see Bazzaz and Ackerly 1992 for a review). A critical feature of life history strategy theories is that increased allocation to one function (e.g. reproduction) must tradeoff with a decreased allocation to another function (e.g. growth). To be of evolutionary significance, cost must be measured in terms of a true limiting resource (Watson 1984, Watson and Casper 1984, Reekie and Bazzaz 1987b, Bazzaz and Ackerly 1992). Another major criticism of biomass allocation is that it does not reflect internal constraints that may control plant growth and life history (Salomonson et al. 1994). Growth in grasses, for example, is constrained by tiller production (Law 1979). Any function that reduces tiller survival (e.g. flowering) decreases growth as only those tillers that survive can produce new tillers. Developmental choices of a plant can affect fitness through overall plant form (architecture). Biomass does not determine plant form (Smith 1984). In this paper we develop an alternative to biomassbased strategy theories based on allocation of above ground meristems in herbaceous flowering plants. Previous studies of meristems in ecology have focussed on several issues. Meristem demography (the births and deaths of modules within a plant) has been used to study growth patterns within a plant (Bazzaz and Harper 1977, Maillette 1982, 1985, 1987, 1990, Lehtila et al. 1994). Fitness may be defined at the level of the module (Tuomi and Vuorisalo 1989a, b). Modules are the units of reproduction, growth and survival and so the cycle of meristems producing new meristems may be used to estimate fitness in clonal plants (Fagerstr6m 1992, Wikberg 1995). Adaptive architecture has been studied via tradeoffs between growth (i.e. branching) and reproduction (Smith 1984, Watson 1984, Geber

615 (PS 3) COMPETITIVENESS OF SIXTEEN WILDFLOWERS WITH BUFFALOGRASS AND BLUE GRAMA TURF

Sixteen species of herbaceous perennial flowering plants were planted with five different treatments (three buffalograss lines, one blue grama line, and no turf) to determine the growth and flowering characteristics of these herbaceous plants with the turf treatments. Plants were measured for survival, time of emergence, percent of plants flowering, initial flowering, number of flower stalks, plant height, and pod number/plant one-year after planting. There were highly significant differences for all traits for plots, species, and plot × species interaction. Individual plant vigor was highest where there was no grass competition. Species that performed well in all turf treatments included Echinacea pallida, Linum perenne, Salvia azurea, Solidago rigida, and Ratibida pinnata.

Upland Kenya Wild Flowers. A Flora of the Ferns and Herbaceous Flowering Plants of Upland Kenya.A. D. Q. Agnew

Previous articleNext article No AccessNew Biological BooksUpland Kenya Wild Flowers. A Flora of the Ferns and Herbaceous Flowering Plants of Upland Kenya. A. D. Q. Agnew John J. GaudetJohn J. Gaudet Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The Quarterly Review of Biology Volume 51, Number 1Mar., 1976 Published in association with Stony Brook University Article DOIhttps://doi.org/10.1086/409144 Views: 1Total views on this site Copyright 1976 Stony Brook Foundation, Inc.PDF download Crossref reports no articles citing this article.

REVIEWS

Book Reviewed in this article: Tropical Forest and its Environment. By K. A. Longman and J. Jeník. Editors: D. W. Ewer and M. D. Gwynne. Upland Kenya Wild Flowers. A Flora of the Ferns and Herbaceous Flowering Plants of Upland Kenya. By A. D. Q. Agnew. Water Plants of the World. By C. D. K. COOK. The History of British Vegetation. By Winifred Pennington. The Biology of Lichens. By M. E. Hale.

A Flora of the Ferns and Herbaceous Flowering Plants of Upland Kenya

A Flora of the Ferns and Herbaceous Flowering Plants of Upland Kenya

THE POPULATION BIOLOGY OF ANNUAL GRASSLAND HEMIPARASITES. I. THE HOST ENVIRONMENT.

Two traits are common to all hemiparasitic plants: the ability to form root grafts with other plants via haustoria, and the presence of functional chlorophyll. Beyond this, further generalizations are not easily made. Hemiparasites grow as annuals, biennials, perennials, woody shrubs, vines and trees in a variety of habitats ranging from equatorial to polar latitudes. The functional nature of each kind of host-parasite relationship will be related to many parameters, among which life form, physical habitat, breeding system, and host characteristics are important. In this continuing series, annual grassland hemiparasites have been singled out for study because of the interesting characteristics of the grassland environment. In California, annual grasslands range from coastal bluffs to hot inland valleys and montane foothills. Most of the species making up this community are alien; it is a new flora not more than 200 years old (Wells, 1964). Species diversity is usually high within and between hemiparasite sites (Thurman, 1966), however, dominance diversity is usually low within a site during any one year (McNaughton, 1968; Heady, 1958) and there can be great variability in the dominant species from year to year. Members of the genus Orthocarpus (Scrophulariaceae) are the most common hemiparasites in California grasslands. These herbaceous flowering plants gain water, minerals, and organic compounds from host plants via haustorial root connections. Haustoria are small, hemispherical, lateral swellings on the parasite roots which penetrate the host root cortex and connect the two vascular systems. Under laboratory conditions of ample water and nutrients, a majority of individuals in most population samples can complete their life cycles without depending upon a host, though they may remain quite small in some species. In nature seedlings may be free-living for up to several weeks in a continually moist soil. Eventually, most population members indiscriminately form haustoria with one or more adjacent plants, and the increased supply of water, minerals, and organic compounds produces the rapid growth phase characteristic of annual hemiparasites. Orthocarpus species and most of their hosts are annuals; consequently, the members of each Orthocarpus population must annually reestablish a successful relationship with one or more individuals from among many potential hosts. Dispersal is normally independent of host plants and their seeds, but exceptions have been noted (Atsatt, 1965). Germination as well is not dependent upon the presence of host plants as has been shown for the genus Striga (Saunders, 1933). Consequently, the annual reassociation of Orthocarpus individuals and their hosts is a random process. The purpose of this continuing investigation is to describe the functional nature of this facultative heterotrophism. We wish to reveal the selective pressures operating upon annual hemiparasite populations and the specific responses to these pressures.