Growth and vegetative spread of Schizachyrium scoparium var. littoralis (Poaceae) in sand dune microhabitats along a successional gradient

1999 ◽  
Vol 77 (2) ◽  
pp. 219-229
Author(s):  
Teresa Valverde ◽  
Irene Pisanty

The architecture resulting from the iteration of modules during plant growth affects resource capture. Phalanx and guerrilla growth forms have been described as ends of a continuum regarding the spacing of modules in plants. In this study we investigated the growth form of the perennial, tussock-forming grass Schizachyrium scoparium Michx. var. littoralis (Nash) Hitchc. in three dune microhabitats at El Morro de la Mancha, southeastern Mexico: a mobile, a semi-mobile, and a stabilized site. We followed the growth of 15 genets at each site for two consecutive years and found that daughter-tussock formation was more frequent in the stabilized than in the semi-mobile or the mobile sites. Individual tussocks had a higher number of tillers in the mobile site than in the other two. Tiller production occurred within parental tussocks in the mobile site and in the form of daughter tussocks in the stabilized site. Reciprocal transplants suggested that phenotypic plasticity was responsible for the differences observed. Fertilization enhanced tiller production within parental tussocks but did not affect daughter tussock formation. Clearing experiments resulted in enhanced tiller production within tussocks. In these experiments, daughter-tussock production did not occur directionally towards nutrient-rich microsites. It appears that S. scoparium tillers are spaced at longer distances when resources are scarce and intraclonal competition is severe.Key words: clonal growth, growth form, nutrient availability, phalanx-guerrilla continuum.


2008 ◽  
Vol 56 (5) ◽  
pp. 437 ◽  
Author(s):  
A. S. Harvey ◽  
F. L. Bird

Rhodolith beds are aggregations of free-living non-geniculate coralline red algae (Corallinales, Rhodophyta), with a high biodiversity of associated organisms. This is the first detailed study of a rhodolith-bed community from the cold-temperate waters of southern Australia. This bed, located at 1–4-m depth in Western Port, Victoria, is composed of four rhodolith-forming species (Hydrolithon rupestre (Foslie) Penrose, Lithothamnion superpositum Foslie, Mesophyllum engelhartii (Foslie) Adey and Neogoniolithon brassica-florida (Harvey) Setchell & Mason). M. engelhartii has a foliose growth form and the other three species have fruticose growth forms. Detailed descriptions are provided for all species, allowing reliable identification. Comparisons with other rhodolith beds and reported rhodolith-forming species, both in Australia and worldwide, are also provided. The invertebrate cryptofaunal community was quantified for two rhodolith-forming species. The density of cryptofauna inhabiting foliose and fruticose rhodolith growth forms did not differ significantly and neither did abundance of individual phyla. Mean density of fauna was 0.4 invertebrates cm–3, the majority of which were polychaete worms. Comparisons of fauna associated with other rhodolith beds are also provided. A study of the vitality of the rhodolith bed showed dead rhodoliths are more abundant than live rhodoliths. Possible reasons for reduced bed vitality are explored.



1971 ◽  
Vol 49 (9) ◽  
pp. 1637-1641 ◽  
Author(s):  
Margaret J. Masters

Phlyctidium bumilleriae Couch was observed attacking Staurastrum pinque, S. chaetoceros, S. muticum, and S. cuspidatum var. divergens in Lake Manitoba during the summers of 1965–1968. S. pinque, the host present in the greatest numbers in the phytoplankton, occurred in a three-radiate, a four-radiate, and an intermediate growth form with three radii on one semicell and four on the other. Both in 1966 and 1967 the four-radiate form was more heavily attacked by Phlyctidium than the three-radiate form although the latter was present in greater numbers. In July 1968, it was the four-radiate form which was more numerous but still it was this form which Phlyctidium most heavily attacked. Intermediate cells succumbed to the fungus in proportions similar to the four-radiate form.



Botany ◽  
2013 ◽  
Vol 91 (7) ◽  
pp. 421-430 ◽  
Author(s):  
M.D. Shafiullah ◽  
Christian R. Lacroix

Myriophyllum aquaticum (Vell.) Verdc. produces two morphologically different forms of leaves based on whether they are aerial or aquatic. The objective of this study was to determine whether there are any similarities or differences between these two growth forms during their early stages of development. A comparative developmental study of aerial and aquatic growth forms of M. aquaticum was conducted from a qualitative and quantitative perspective using a scanning electron microscope. The pattern of leaf and lobe initiation such as their origin and shape were similar in both growth forms until the fourth plastochron (stage P4). Differences between the two growth forms became evident from stage P5 onward, where a larger shoot apical meristem (SAM), elongated epidermal cells, shorter and slightly more numerous lobes, as well as the presence of appendage-like structures characterized aquatic growth forms. On the other hand, aerial growth forms had smaller SAM, bulb-like epidermal cells, and longer and slightly less numerous leaf lobes. Significant differences between growth forms were noted for parameters such as volume of SAM, length of terminal, first, and middle lobes, as well as the length from first to last lobes. The volume of the SAM of aquatic shoot tips was always greater than aerial forms. On the other hand, lobes of aerial forms were always longer than the aquatic counterpart during early stages of development. This study on the development of M. aquaticum shows that the aerial and aquatic growth forms diverge from their early stages of development.



2011 ◽  
Vol 5 (9) ◽  
pp. 57 ◽  
Author(s):  
R. Bernabéu ◽  
M. Olmeda ◽  
M. Díaz

This paper covers a dual objective. On the one hand, the relative importance was determined of the wine attributes that influence the formation of consumer preferences in Castilla-La Mancha. On the other, consumer attitude was analysed towards wine with Castilla-La Mancha’s most important Designation of Origin (D.O.) certifications (D.O. La Mancha and D.O. Valdepeñas), compared with the best-known wine in the national ambit (D.O. Rioja). As a result of the first objective, the most relevant attributes are price, colour (red, white), certification and origin, in this order. The second objective shows that D.O. La Mancha and D.O. Valdepeñas are considered cheaper wines, of habitual consumption and a lower prestige image, while D.O. Rioja wines are seen as prestigious and expensive, so their consumption is considered appropriate for special occasions.



1991 ◽  
Vol 48 (1) ◽  
pp. 123-131 ◽  
Author(s):  
Michele Dionne ◽  
Carol L. Folt

In this laboratory study we measured the independent effects of macrophyte growth form, plant density, and prey abundance on the foraging rate of the pumpkinseed sunfish (Lepomis gibbosus). We demonstrate that macrophyte growth forms are not all similar in their effects on fish foraging. Prey capture rates of pumpkinseeds foraging among Scirpus validus (cylindrical stems) were 53 and 365% times greater than for Potamogeton amplifolius (leafy stems) for cladoceran (Sida crystallina) and larval damselfly (Coenagrionidae) prey, respectively. Plant growth form influenced prey capture rates more than charges in natural plant density. Plant density effects ranged from none on damselfly capture rates to a 29% decline in cladoceran capture rate over a twofold increase in plant density. Our results indicate that in plant-structured habitats, variation in plant growth form can be an important determinant of fish foraging and habitat associations.



2003 ◽  
Vol 9 (1) ◽  
pp. 33-41 ◽  
Author(s):  
E. García ◽  
J. L. Chacón ◽  
J. Martínez ◽  
P. M. Izquierdo

Changes in volatile compounds in musts and skins of grapes of Airén, Macabeo and Chardonnay white varieties were determined during ripening. The musts of the Airén variety contained higher concentrations of c-3-hexenol; musts of the Macabeo variety were the richest in t-3-hexenol and 2,4-hexadienal, while the Chardonnay musts stood out for having higher concentrations of benzaldehyde, phenylacetaldehyde and benzyl alcohol. The skins of the three varieties were both qualitatively and quantitatively richer in volatiles than were the musts. The skins of the Airén grapes had the highest levels of nerol. Airén grapes were the only variety in which citronellol was present in the skins. Low concentrations of eugenol were detected in the skins of the Chardonnay grape variety but were not present in the other two varieties. Changes in the concentration of the volatile compounds during ripening were not uniform; this made difficult the determination of the optimum level of ripening for each variety on the basis of the volatile compound content. Nevertheless, results indicated that C6 compounds and terpene concentrations reached a maximum at 6-8 ° Baumé in the Airén grapes and at around 11 ° Baumé in the Chardonnay and Macabeo grapes.



Bothalia ◽  
1983 ◽  
Vol 14 (3/4) ◽  
pp. 653-659 ◽  
Author(s):  
H. E. K. Hartmann

Many taxa of the family Mesembryanthemaceae show close correlations between distribution and environmental factors, e.g. occurrence on limestone or quartzite only, but few cases have been studied in detail. Recent investigations in anatomy, morphology, life cycles, physiology, and in energetic properties indicate that fundamentally different patterns are developed in adaptation to arid conditions, even in reaction to identical edaphic and climatic factors.On the other hand, little is known about the immediate influence of changes in the natural environment. Studies in populations of the subgenus Cephalophyllum of the genus  Cephalophyllum N.E. Br. show strong correlations between precipitation data and habit, which can superimpose genetic dispositions. In addition, growth forms are well adapted to certain types of plant communities, so that superficially, a diffuse structural pattern results.Long term studies, in the field and in the greenhouse, of growth forms in relation to time, to precipitation, and to associations, allow first suggestions for adaptive pathways in the evolution of the group, and the results form a basis for taxonomic decisions in this highly confused taxon. Finally, the example offers aspects for the better understanding of interaction between ecology and distribution data.



PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1984 ◽  
Author(s):  
Thomas Swierts ◽  
Mark JA Vermeij

Turf algae are becoming more abundant on coral reefs worldwide, but their effects on other benthic organisms remain poorly described. To describe the general characteristics of competitive interactions between corals and turf algae, we determined the occurrence and outcomes of coral–turf algal interactions among different coral growth forms (branching, upright, massive, encrusting, plating, and solitary) on a shallow reef in Vietnam. In total, the amount of turf algal interaction, i.e., the proportion of the coral boundary directly bordering turf algae, was quantified for 1,276 coral colonies belonging to 27 genera and the putative outcome of each interaction was noted. The amount of turf algal interaction and the outcome of these interactions differed predictably among the six growth forms. Encrusting corals interacted most often with turf algae, but also competed most successfully against turf algae. The opposite was observed for branching corals, which rarely interacted with turf algae and rarely won these competitive interactions. Including all other growth forms, a positive relationship was found between the amount of competitive interactions with neighboring turf algae and the percentage of such interaction won by the coral. This growth form dependent ability to outcompete turf algae was not only observed among coral species, but also among different growth forms in morphologically plastic coral genera (Acropora, Favia, Favites, Montastrea, Montipora, Porites) illustrating the general nature of this relationship.



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