Showing papers on "Polygonum published in 1995"

Inter- and intra-generic differences in growth, reproduction, and fitness of nine herbaceous annual species grown in elevated CO2 environments.

Abstract: In assessing the capacity of plants to adapt to rapidly changing global climate, we must elucidate the impacts of elevated carbon dioxide on reproduction, fitness and evolution. We investigated how elevated CO2 influenced reproduction and growth of plants exhibiting a range of floral morphologies, the implications of shifts in allocation for fitness in these species, and whether related taxa would show similar patterns of response. Three herbaceous, annual species each of the genera Polygonum, Ipomoea, and Cassia were grown under 350 or 700 ppm CO2. Vegetative growth and reproductive output were measured non-destructively throughout the full life span, and vegetative biomass was quantified for a subsample of plants in a harvest at first flowering. Viability and germination studies of seed progeny were conducted to characterize fitness precisely. Early vegetative growth was often enhanced in high-CO2 grown plants of Polygonum and Cassia (but not Ipomoea). However, early vegetative growth was not a strong predictor of subsequent reproduction. Phenology and production of floral buds, flowers, unripe and abscised fruits differed between CO2 treatments, and genera differed in their reproductive and fitness responses to elevated CO2. Polygonum and Cassia species showed accelerated, enhanced reproduction, while Ipomoea species generally declined in reproductive output in elevated CO2. Seed "quality" and fitness (in terms of viability and percentage germination) were not always directly correlated with quantity produced, indicating that output alone may not reliably indicate fitness or evolutionary potential. Species within genera typically responded more consistently to CO2 than unrelated species. Cluster analyses were performed separately on suites of vegetative and reproductive characters. Some species assorted within genera when these reproductive responses were considered, but vegetative responses did not reflect taxonomic affinity in these plants. Congeners may respond similarly in terms of reproductive output under global change, but fitness and prognoses of population persistence and evolutionary performance can be inferred only rarely from examination of vegetative characters alone.

Identification of allelochemicals in Eucalyptus citriodora and Polygonum sachalinense

Abstract: The relationship between the allelochemicals, p-menthane-3,8-diols (cis and trans) and the ontogenetic age in Eucalyptus citriodora was elucidated. The diols in the soil from a Eucalyptus grove were analysed by chromatography. On the other hand, the root exudates from Polygonum sachalinense in a recirculating system significantly inhibited lettuce seedling growth. Bioassay of the neutral-acidic fraction on the TLC agar plate showed the inhibitory activity corresponded to the two yellow pigments. Two compounds were isolated and identified as anthraquinone compounds; emodin and physcion. The results indicate that these anthraquinones are responsible for the observed interference in nature and are potent allelochemicals

[Pharmacological studies of Polygonum capitatum Buch-Ham. ex D. Don].

Abstract: The pharmacological effect of aqueous extract of Polygonum capitatum has been studied. The experimental results show that Polygonum capitatum markedly decreases WBC and RBC in urine of pyelonephritis mode in rats, the death rate of Escherichia coli infected mice, and the temperature of feverish rabbits. It has also been found that after oral administration of Polygonum capitatum the animal urine markedly inhibits the growth of Escherichia coli, but diuretic action of the herb has not been observed.

Variability of photosynthetic gas exchange parameters, dark respiration, and stomatal numbers in species of Polygonum

Abstract: Within the genus Polygonwn a large variation was found between species with regard to stomatal number, gas phase resistance, intracellular resistance and dark respiration. Interspecific variation in CO 2 compensation concentration and intercellular CO 2 concentration at constant external concentration were comparatively small. Correlations were found between stomatal number and gas phase resistance, stomatal number and Γ, and Γ and the product of dark respiration rate and intracellular resistance. The influence of dark respiration and stomatal number on photosynthetic gas exchange is discussed. It was concluded that dark respiration in light was enhanced by 22% as a mean value in 9 Polygonum species and by 62% in Polygonum lapathifolium.

Polygonum hickmanii (Polygonaceae), a New Species from California

Abstract: A new endemic species of Polygonum is described from Scotts Valley, California. Differentiation from closely related taxa P parryi and P heterosepalum is presented. Polygonum (sect. Duravia) hickmanii H. R. Hinds & R. Morgan, sp. nov. TYPE: U.S.A. California: Santa Cruz County, Scotts Valley, grassland N of Navarra Drive, W of Carbonero Creek, 1 July 1993, R. Morgan 2119 (holotype, CAS; isotypes, MO, RSA, UC, UNB). Hickman's knotweed. Herba annua. Folia sessilia, 0.5-3.5 cm X 1-1.5 mm, revoluta. Ocrea divisa ad basem in longas rectas fibras. Flores singuli in axillis omnium paene bracteorum foliorum. Achenia laevia, (2-)2.3 X 1.6 mm, duobus lateribus concavis et uno latere latiore planioreque. Erect taprooted annual, 2-5 cm, simple in depauperate plants to profusely branched from near the base. Leaves sessile, linear, acuminate, mucronate, 0.5-3.5 cm X 1-1.5 mm, revolute and wingnerved below, closely investing and with the ocreae + concealing the stems. Ocrea 6 mm long, silvery, divided nearly to base into long straight filaments, adnate to the base of the leaves and appearing almost as long as the apical leaves. Flowers single in axils of almost all bracteal leaves, tepals white, with two outer tepals cucullate and mucronate, 3 mm long, three inner tepals rounded to obtuse 2 mm long, anthers conspicuous, orange-pink 0.4 mm. Achenes smooth, (2-)2.3 X 1.6 mm, light to dark olive brown, lighter on the angles, with two concave sides and one broader + flat side; not exserted. Styles 0.3 mm, persistent. Flowering from late May to August (October). Polygonum hickmanii is known from two sites about one mile apart, at the northern end of Scotts Valley, Santa Cruz County, California, at about 700-800 feet elevation and occurs only in very restricted microhabitats within an isolated relictual grassland. The sites are gently sloping to nearly level, with fine-textured shallow soil over outcrops of Santa Cruz mudstone and Purisima sandstone, sparsely vegetated with small annual herbs. This habitat is shared with a more abundant but equally narrow endemic, Chorizanthe robusta C. Parry var. hartwegii (Bentham) J. Reveal & R. Morgan. The population of Polygonum hickmanii fluctuated from about 200 to 400 plants in 1990-1992 to 1000 or more in 1993 following a relatively wet winter. Polygonum hickmanii is sympatric with no other members of the section Duravia. The nearest location of a closely related species, P. parryi Greene (itself disjunct), is at Mt. Hamilton about 50 miles inland. Polygonum hickmanii differs from P. parryi in its larger white flowers, longer leaves, larger anthers and achenes, and longer, straight ocreae. It differs from P. heterosepalum M. E. Peck & Ownbey in achene shape (more rounded at base as opposed to more tapering), size (1.5-2 mm), and flower structure (perianth segments very unequal). Polygonum hickmanii is named for James C. Hickman (1941-1993), distinguished botanist, who confirmed the uniqueness of this taxon and whose advice and inspiration is here acknowledged. Acknowledgments. The authors thank George Flanders, Irene Johnston, and John Geyssen for their considerable assistance with manuscript preparation.

Nomenclatural changes in Polygonum, Persicaria, and Aconogonon (Polygonaceae)

Abstract: Polygonum caurianum subsp. hud- sonianum is raised to species rank. Polygonum bistortoides is transferred to Persicaria, and Po- lygonum alaskanum var. glabrescens is transferred to Aconogonon. For the forthcoming treatment of Polygonum s.1. for the Flora of North America, several new no- menclatural combinations are required to reflect new knowledge in the taxonomy of this group.