Rhizomatous Perennials Research Articles

New Approach to the Systematics of the Section Psammiris (Iris, Iridaceae): What Does Chloroplast DNA Sequence Tell Us?

Iris sect. Psammiris comprises rhizomatous perennials distributed in the north temperate zone of Eurasia. The systematics of the section are currently based on morphology, and the phylogenetic relationships within it still remain unclear. In the framework of Iris systematics, we conducted molecular and morphological analyses of the currently recognized I. sect. Psammiris species to elucidate the taxonomic composition and relationships within the section. The phylogenetic reconstructions based on sequence variation of four noncoding chloroplast DNA regions support the monophyly of I. sect. Psammiris, which includes I. tigridia, while I. potaninii var. ionantha belongs to I. sect. Pseudoregelia. The proposed novel classification of I. sect. Psammiris recognizes three series: an autonymic series with I. humilis, I. bloudowii, and I. vorobievii and two unispecific series (I. ser. Potaninia with I. potaninii and I. ser. Tigridiae with I. tigridia). In addition, the taxonomic statuses of I. arenaria, I. ivanovae, I. kamelinii, I. mandshurica, I. pineticola, I. psammocola, and I. schmakovii are clarified herein. We provide a revised taxonomic treatment for I. sect. Psammiris, including notes on the types; updated information on species synonymy, distributions, habitats, and chromosome numbers; and a new identification key to the species. Three lectotypes are designated here.

Псаммофитная растительность долины реки Худан (Республика Бурятия)

Псаммофитная растительность долины реки Худан (Республика Бурятия)

Beginner's Guide to Begonias: Begonia rex-cultorum

Rex begonias are spectacular rhizomatous perennials famous for their variegated, colorful foliage and ease of growth. Rex begonias are well suited for hanging baskets, windowsills, or houseplants. In more tropical climates, like Florida, rex begonias can also be found adding vibrant foliage and dimension to landscapes. This new 3-page publication of the UF/IFAS Environmental Horticulture Department is meant for Florida homeowners and horticulturalists interested in learning more about begonias.https://edis.ifas.ufl.edu/ep632

Response of riparian vegetation to short- and long-term hydrologic variation.

Increasing demand for river water now conflicts with an increasing desire to maintain riparian ecosystems. Efficiently managing river flows for riparian vegetation requires an understanding of the time scale of flow effects, but this information is limited by the absence of long-term studies of vegetation change in response to flow variation. To investigate the influence of short- and long-term flow variability and dam operation on riparian vegetation, we determined the occurrence of 107 plant species in 133 permanent plots of known inundating discharge along the Gunnison River in Colorado on five different occasions between 1990 and 2013. Individual species moved up and down the gradient of inundating discharge coincident with increases and decreases in mean annual flow, and the correlations between flow and species occurrence were strongest when flows were weighted by time before vegetation sampling with a median half-life of 1.5 years. Some tall, rhizomatous, perennial species, however, responded to flows on a longer time scale. Logistic regression of species occurrence showed a significant relation with inundation duration for 70 out of 107 species. Plot species richness and total vegetative cover decreased in association with desiccation at low inundation durations and with fluvial disturbance at high inundation durations. Within-plot similarity in species occurrence between years decreased strongly with increasing inundation duration. Moderate inundation durations were dominated by tall, rhizomatous, perennial herbs, including invasive Phalaris arundinacea (reed canary grass). Over the 23-year study period, species richness declined, and the proportion of rhizomatous perennials increased, consistent with the hypothesis that decreases in flow peaks and increases in low flows caused by flow regulation have decreased establishment opportunities for disturbance-dependent species. In summary, annual-scale changes in vegetation were strongly influenced by flow variation, and decadal-scale changes were influenced by decreases in fluvial disturbance from upstream flow regulation beginning decades prior to the onset of this study.

Specialized pollination by fungus gnats in the introduced population of Aspidistra elatior.

The monocot genus Aspidistra comprises rhizomatous perennials that are distributed in tropical to warm temperate regions of Asia. Little is known about the pollinators of almost all the species, probably due to the inconspicuous nature of Aspidistra flowers. Nevertheless, the unusual floral morphology suggests biotic pollination, since pollen grains are hidden under each flower's stigma. Aspidistra elatior has been suspected to have a very peculiar pollination ecology. So far, pollination by mollusks, crustaceans, or collembolans has been suspected. However, a recent study showed that A. elatior is mainly pollinated by species of fungus gnats in Kuroshima Island, southern Japan, which is its natural habitat. Here, we investigated the pollination ecology of A. elatior in Shiga Prefecture, central Japan, which is the introduced population, to reveal whether fungus gnats are also the main pollinator in the introduced population. Our study confirmed fungus gnats pollination in the investigated pollination. Furthermore, the main pollinators (i.e., Cordyla sixi and Bradysia sp.) are the same in both Kuroshima and Shiga Prefecture. Therefore, A. elatior mainly depends on a narrow taxonomic group of fungus gnats for pollination. In contrast, we failed to document any terrestrial amphipods visiting the A. elatior flowers, in spite of a relatively high fruit set in natural conditions. This fact will refute the amphipod pollination hypothesis proposed by previous studies. We consider that A. elatior is pollinated by fungus gnats through fungal mimicry, due to its superficial similarity to mushroom fruiting bodies and strong, musky floral scent.

The geometry of gender: hyper-diversification of sexual systems in Urtica L. (Urticaceae).

Urtica L. (Urticaceae) is generally reported as a genus of monoecious and dioecious taxa. However, the gender information found in the literature does not at all reflect the actual diversity of gender patterns in Urtica. Dioecy appears to be truly absent from Urtica, but otherwise there has been a major diversification in the geometry of gender and no comparable patterns exist in other plant groups. Thus, we here define technical terms for all unique architectural types of monoecy found in Urtica and closely related genera and reconstruct the ancestral gender states in a Bayesian framework. Our studies are based on a near-comprehensive sampling, including 61 of the 63 Urtica species recognized. We report polygamy, two types of gynodioecy and five different architectural types of monoecy. A total of 15 switches appear to have taken place within the genus. Although gender characteristics have diversified strongly, they are relatively conserved within clades. Monoecy is the predominant sexual system within Urtica and specifically basiandrous monoecy (i.e. basal inflorescence branches of each individual male only, apical branches female) is the most widespread type, reported for 11 different clades. In particular, it characterizes the basally branching pilulifera-clade and the sister genus Zhengyia, and may thus represent the plesiomorphic condition for Urtica. Gender distribution and gross morphology appear to evolve largely independently from each other and gender distribution is largely independent of growth habit. However, polygamous taxa are most common amongst rhizomatous perennials (one-third of the taxa).

Seasonal variation in sprouting capacity from intact rhizome systems of three perennial weeds

SummaryThe three rhizomatous perennials Elytrigia repens, Equisetum arvense and Tussilago farfara are all problematic in Scandinavian agriculture, due to their low susceptibility to soil cultivation. While repeated soil tillage is a fundamental part of the integrated control of these species, it is highly energy consuming and inefficient during periods when little sprout regrowth occurs. Substituting cultivation with mowing will reduce the environmental impact and labour costs, but its efficiency will still depend on the capacity of plants to sprout. Therefore, we studied the seasonal pattern in emergence and rhizome biomass allocation from July to April in six populations for each of the species. Plants were grown outdoors in pots buried in soil and exhumed at regular intervals in a two‐year experiment. In all three species, biomass allocation to rhizomes continued until late in the autumn. Emergence was severely impaired in E. arvense and T. farfara in September–October, while in E. repens, there was no such reduction in the number of emerged shoots. However, in the latter species, the shoot/rhizome ratio decreased and remained low until the plants had been exposed to a period of low temperatures. The increase in shoot/rhizome ratio for E. repens coincided with the resumed capacity to emerge for E. arvense and T. farfara. These results imply that there is no need to repeat a defoliation of E. arvense and T. farfara, if carried out in September–October. However, removal of the aerial plant parts early in the autumn is important to interrupt the upload of storage compounds to the rhizome systems of all species.

Classification of Roadside Weeds along Two Highways in Different Climatic Zones According to Ecomorphological Traits

Growth of vegetation in curbside cracks causes deterioration of asphalt and curbs, reducing road longevity and safety capabilities. Road managers spend a considerable amount of time and money on roadside vegetation management every year. The vegetation in curbside cracks in these study regions is managed approximately once a year by mowing and road sweeping using street-sweeper trucks. Nevertheless, ideal management practices of roadside vegetation have not yet been established partly due to insufficient knowledge of the ecological strategies of plants invading roadsides, especially curbside cracks. Although establishment of plants in the cracks might be restricted due to severe anthropogenic road disturbances, the cracks could be habitats for species with specific ecological traits. The objective of this study was to clarify the floristic and functional characteristics of roadside weeds, particularly species invading curbside cracks, to provide information for effective road management. The species composition of plants invading the cracks was surveyed along Route 3 (southern Japan) and Route 4 (eastern Japan) in different climatic zones, based on 108 floristic inventories. We compared species occurrence and composition to characterize the dominant ecomorphological traits of the species. In total, 163 species occurred in curbside cracks along both routes. Species composition of vegetation in curbside cracks was more variable between the routes than between land-use types. Of the 54 species, more than 5% occurred in all plots, and only three had differences in occurrence among land-use types. Ecomorphological trait composition patterns of the species were similar across land-use types. From these results, we found that regardless of differences in species composition among regions, climatic conditions, and surrounding land-use type, there were some dominant ecomorphological traits of roadside vegetation with plants in curbside cracks, such as ephemeral monophytes that are barochorous or anemochorous. By contrast, rhizomatous perennials, which cause greater deterioration of asphalt than ephemeral monophytes, were rare along the cracks. Although vegetation composition and structure generally depend on land-use types and disturbance regimes, linear landscape elements such as curbsides might be habitats for plants adapted to road disturbances. Roadside vegetation management, such as mowing and road sweeping once a year, seems sufficient to restrict establishment of rhizomatous perennials around Japan.

Strong regeneration ability from rhizome fragments in two invasive clonal plants (Solidago canadensis and S. gigantea)

The two rhizomatous perennials Solidago canadensis and S. gigantea belong to the most widespread alien plants in Europe. Anecdotal observations suggest that they disperse also by rhizome fragments. For testing their resprouting ability, rhizome fragments of different sizes from both species were buried at four different soil depths (0, 5, 10 and 20 cm, respectively) in a common garden. Rhizome fragments of S. canadensis ranged 3–6 cm in length, those of S. gigantea 5–20 cm in length. Resprouting plants were harvested after 3 months and growth related traits measured to assess their vitality. Resprouting rate in S. gigantea was far higher than in S. canadensis (85 and 19%, respectively). In S. gigantea, fragments of all sizes resprouted from all soil depths whereas none rhizome of S. canadensis emerged from 20 cm burial depth. In S. gigantea, size related traits showed significant interactions between fragment size and burial depth, but not relative shoot growth rate. At all burial depths, vitality of plants emerging from small rhizomes was lower than plants emerging from large rhizomes. Effects of rhizome size became stronger with increasing burial depth. The results show that both species are able to resprout from buried rhizome fragments, and that succesful regeneration is more likely to occur in S. gigantea. Managing these species should avoid any activities promoting rhizome fragmentation and dispersal of fragments.

Restoration of weed communities in abandoned rice paddy fields in the Tama Hills, central Japan

Abstract Since paddy weed communities are declining with intensification and abandonment of agricultural activities, protecting these species has become important. The restoration of cultural ecosystems normally includes the concomitant recovery of indigenous management practices. Given that the abandonment of paddy fields is due largely to cost and the shortage of labour, reintroduction of annual farming is unlikely even if paddy fields are restored. Hence, to confirm the occurrence of species assemblages typically represented in rice paddy fields (typical paddy weeds: TPWs) and to determine how to decrease the expense and management burden, we instituted a restoration program in which traditional rice culture was restarted with some modifications such as introducing fallow periods in paddy fields abandoned for more than 10 years. We also investigated cultivated rice paddy fields where local farmers practise low-intensity farming and newly abandoned paddy fields as references. By comparing the floristic composition between restored and reference fields, we sought to meet two objectives: (1) to evaluate the efficacy of the restoration program in terms of the species composition of paddy weed communities in restored paddy fields, and (2) to identify the optimum fallow period to decrease the expense and management burden. Restarting agricultural practices in abandoned paddy fields successfully encouraged TPWs. Moreover, restoration of the TPW community was rapid, with no resilient or alternative state in the restoration program. Soil tillage and water management appeared to be major factors determining the success of the restoration. Tillage restricted the dominance of rhizomatous perennials and provided habitats for low-stature summer annuals. Reintroduction of submergence as a water management practice generally inhibits the occurrence of most TPWs. However, the unlevelled soil surface in the present study provided suitable conditions for these species. One-year fallow produced the highest abundance of TPWs in a transient stage influenced by antecedent effects of rice culture such as drainage after rice harvest, delay of competitive species incidence, and lack of submergence as an agricultural treatment. The number of TPWs declined steadily with increasing fallow period. This evidence indicates that to maintain paddy weeds in the emergent flora, it is appropriate to create 1-year fallow conditions; that is, to cultivate every other year.

A quantitative review comparing the yields of two candidate C4 perennial biomass crops in relation to nitrogen, temperature and water

Abstract C 4 herbaceous rhizomatous perennials have many positive attributes as potential and actual biomass energy crops on agricultural land. Two species from this group have become widely planted. Miscanthus × giganteus has been extensively studied and planted in Europe, and Panicum virgatum in N. America. To date, side-by-side comparisons of mature stands of these crops have not been reported in the peer-reviewed literature. We examined all peer-reviewed articles describing productivity of these species and extracted dry matter yields, nitrogen fertilization (N), temperature (growing degree days) and precipitation/irrigation. Only yields reported 3 or more years after planting were included. Despite being on different continents, trials spanned similar temperature, N and water ranges. Miscanthus × giganteus (97 observations) yielded an average 22 Mg ha −1 compared to 10 Mg ha −1 for P. virgatum (77 observations). Both crops showed a significant positive response to water and N, but not to temperature. Miscanthus × giganteus yielded significantly more biomass than P. virgatum across the range of all three variables. There were differences between the species in their apparent responses to these variables. Miscanthus × giganteus showed a stronger response to water, while P. virgatum showed a significantly stronger response to nitrogen. Since energetic viability, and profitability, of biomass crops hinges critically on high outputs of biomass energy for low inputs of money and fossil fuels, these results suggest that M . × giganteus holds greater promise for biomass energy cropping than does P. virgatum across the range of trial conditions undertaken to date.

Phylogenetic reconstruction of the genusBrachypodium P. Beauv. (Poaceae) from combined sequences of chloroplastndhF gene and nuclear ITS

A phylogenetic reconstruction of eight species of the genusBrachypodium P. Beauv. (Poaceae) has been obtained combining sequence data from the chloroplastndhF gene and the nuclear ITS, and using five representatives of tribes Triticeae (Secale), Poeae (Lolium), Meliceae (Melica, Glyceria) and Oryzeae (Oryza) as out-groups. Similar numbers of informative substitutions for the ingroup species were provided by both the 3′ region of the chloroplastndhF gene and the nuclear ITS region. The Mediterranean annualBrachypodium distachyon appears to be the basal lineage, followed by the divergence of the New World non-rhizomatousB. mexicanum, which antedates the separation of a core of six European and Eurosiberian rhizomatous perennials (Brachypodium arbuscula, B. retusum, B. rupestre, B. phoenicoides, B. pinnatum, andB. sylvaticum). The evolutionary reconstruction based on sequences of the chloroplast and the nuclear genomes is congruent with topologies obtained from analysis of RAPD data.

Studies in Cyperaceae in southern Africa. 34: Fuirena coerulescens, a polymorphic species

Fuirena gracilis Kunth, F . enodis C.B. Clarke, F . subdigitata C.B. Clarke and F . reticulata Kuk. are placed in synonymy under F . coerulescens Steud. All are rhizomatous perennials with identical indumentum, glumes and nutlets. Previously, they were separated from each other largely by the nature of the hypogynous whorls but intergrading variation was found in the size and shape of these structures and in the other characters investigated. The species are therefore united without recognition of infraspecific taxa.

Kyllinga, a Genus of Neglected Weeds in the Continental United States

The sedge genus Kyllinga consists of 40 to 45 species distributed in tropical, subtropical, and warm temperate regions around the world (KUkenthal 1936; Tucker 1987). This genus of low rhizomatous perennials or cespitose annuals is classified in the large cosmopolitan family Cyperaceae. Many Kyllinga species are considered weedy (Holm et al. 1979; Tucker 1987), while Kyllinga nervosa Steudel is considered an important forage plant in Africa (McNaughton 1985).

Channel Narrowing and Vegetation Development Following a Great Plains Flood

Streams in the plains of eastern Colorado are prone to intense floods following summer thunderstorms. Here, and in other semiarid and arid regions, channel recovery after a flood may take several decades. As a result, flood history strongly influences spatial and temporal variability in bottomland vegetation. Interpretation of these patterns must be based on understanding the long—term response of bottomland morphology and vegetation to specific floods. A major flood in 1965 on Plum Creek, a perennial sandbed stream, removed most of the bottomland vegetation and transformed the single—thread stream into a wider, braided channel. Channel narrowing began in 1973 and continues today. In 1991, we determined occurrences of 150 vascular plant species in 341 plots (0.5 m2) along a 7—km reach of Plum Creek near Louviers, Colorado. We related patterns of vegetation to elevation, litter cover, vegetative cover, sediment particle size, shade, and year of formation of the underlying surface (based on age of the excavated root flare of the oldest woody plants). Geomorphic investigation determined that Plum Creek fluvial surfaces sort into five groups by year of formation: terraces of fine sand formed before 1965; terraces of coarse sand deposited by the 1965 flood; stable bars formed by channel narrowing during periods of relatively high bed level (1973—1986); stable bars similarly formed during a recent period of low bed level (1987—1990); and the present channel bed (1991). Canonical correspondence analysis indicates a strong influence of elevation and litter cover, and lesser effects of vegetative cover, shade, and sediment particle size. However, the sum of all canonical eigenvalues explained by these factors is less than that explained by an analysis including only the dummy variables that define the five geomorphically determined age groups. The effect of age group is significant even when all five other environmental variables are specified as covariables. Therefore, the process of postflood channel narrowing has a dominant influence on vegetation pattern. Channel narrowing at Plum Creek includes a successional process: annual and perennial plants become established on the channel bed, sediment accretes around the vegetation, and increasing litter cover, shade, and scarcity of water eliminate species that are not rhizomatous perennials. However, successional trajectories of individual surfaces are modified by flow—related fluctuations of the bed level; surfaces deposited by the 1965 flood have had distinct sediment and vegetation since their formation. Species richness is highest on surfaces dating to 1987—1990; the many species restricted to this transitory assemblage are perpetuated by flood—related fluctuations in channel width. Since the 1965 flood, seedling establishment of the dominant trees (genus Populus) has occurred only on low surfaces formed during channel narrowing. Thus, the flood has indirectly promoted Populus establishment over a 26—yr period.

Succession and Fire Season In Experimental Prairie Plantings

Fire season influenced the cover of species and flowering guilds of plants in replicated grass and forb plantings of tallgrass prairie species in Wisconsin. Over two burn cycles at 3—yr intervals, cover increased in the rhizomatous perennials Andropogon gerardii, Aster simplex and Solidago altissima in plots burned in spring, or summer, or left unburned, but cover showed dramatic positive or negative responses to spring or summer burns in Agropyron repens, Erigeron annuus, Panicum virgatum, Phalaris arundinacea, and Rudbeckia hirta. Aggregate response of flowering guilds was stronger. By the last (1993) census, the phenological guild flowering before mid—July (summed cover values for nine species) accounted for 4% cover in unburned plots and <2% cover in plots burned in early spring, but 32% cover in plots burned in midsummer. The late—flowering guild (summed values for 21 species) accounted for 93% cover in unburned plots and 97% cover in plots burned in early spring, but 66% cover in plots burned in midsummer. Remaining space was taken by a mid—season guild (11 species), only one of which (E. annuus) was common enough for individual statistical analysis. These results have implications for succession of prairie vegetation under different seasonal fire regimes. Over 8 yr, summer fires that simulated the timing of lightning fires retarded progression to dominance of large, late—flowering C4 grasses, allowing early—flowering species eliminated in other treatments to persist or even prosper. Primaeval lightning fires in midsummer may have produced quite different communities than anthropogenic fires, which are rarely set during the middle of the growing season.

Nomenclatural Changes and New Taxa in Claytonia (Portulacaceae) in Western North America

Nomenclatural Changes and New Taxa in Claytonia (Portulacaceae) in Western North America

Influence of Frost Heaving on Soil Chemistry and on the Distribution of Plant Growth Forms

This study indicates that vegetation on frost heaved soils is controlled by two main factors: (1) disruptive effects on the belowground parts of the plants when the soil heaves; (2) an increase of nutrient availability, pH, and base saturation following this disturbance. The vegetation changes from a dominance of rhizomatous (mostly graminoids) and woody plants (shrubs and dwarf shrubs) on stable soils, via dominance of dwarf shrubs alone on soils of low disturbance, to dominance of fibrous rooted perennials at the strongest disturbance. I suggest that rhizomatous plants are adapted to grow at sites with a continuous humus cover where they easily can penetrate and exploit the organic matter. They are excluded, however, from frost heaved ground because no continuous humus layer is formed, due to the disturbance. Woody plants are favoured by lack of competition from rhizomatous perennials on soils of low disturbance but they are not able to withstand the disruptive forces of strong frost heaving. The fibrous-rooted plants are not severely damaged even by intense frost heaving since their belowground systems die to a great extent before the onset of freeze-thaw cycles in late autumn. Instead they are problably favoured by the disturbance because competition is reduced, and because they are adapted to high nutrient availability as evidenced by the short lifespan of their root system.

Beiträge zur Wuchsformendifferenzierung und systematischen Gliederung von Teucrium L. IV. Wuchsformen und Verbreitung von Arten der Sektion Isotriodon ,

The growth form analysis of the species of Teucrium sect. Isotriodon revealed the following differentiation: evergreen dwarf semishrub-chasmophytes with lignified branches (T. halacsyanum, T. montbretii) to summer-green pleiokormous and rhizomatous perennials with subterraneous stems or stolons (T. quadrifarium, T. japonicum) . Strong, partly split lignified roots, dense, intensively tomentose branching systems with ascendent to decumbent branches and small, pilose leaves are characteristic in chasmophytic species. These species grow exclusively on rocky places and they are elements of a characteristic cliff vegetation. The herbaceous Teucrium species of sect. Isotriodon are characterized by relatively large leaves and richly blooming, relatively short inflorescences. All species are characteristic representatives in communities of forests and meadows. With regard to the chorological division of the different growth forms, there is a clear separation in an oceanic-suboceanic area of the east-side and a suboceanic-subcontinental area of the west-side. The evergreen dwarf semishrub-chasmophytes of the Mediterranean climatic region are locally distributed, whereas the perennials are predominantly wide spread. On account of the growth form analysis, the chorological differentiation and the phytocoenological affinity, the species of the west-side area can be classified as relics. The numerous species in the sect. Isotriodon of the east- and central-chinese area represent probably a centre of high species-diversity.

Morphological and Cytological Variation in the Western North American Aster occidentalis Complex (Asteraceae)

The Aster occidentalis complex is a western North American group of rhizomatous perennials. The group shows considerable morphological variation and includes at least six ploidy levels with chromosome numbers ranging from n = 8 to n = 48. In this study, 283 chromosome counts are reported; most specimens sampled had euploid chromosome numbers based on x = 8, but a few aneuploid plants were also found. The relationship between morphological variation and chromosome number was assessed using a cluster analysis and principal components analysis of up to 35 characters in 172 specimens of known ploidy level. The diploid specimens fell into six morphological groups, corresponding to five of the approximately ten species included in the complex. The polyploids showed greater variability and more extensive intergradation between groups than did the diploids. The geographic distributions of chromosome numbers in the more widely distributed species are also discussed. Aster, taxonomically one of the most difficult of North American genera, has presented sys- tematists with numerous problems in delimit- ing species boundaries and determining rela- tionships. The genus is cytologically variable and contains chromosome numbers based mainly on x = 5, 8, and 9; both aneuploids and polyploids have been reported (Dean 1966; Dean and Chambers 1983; Jones 1980b; Semple