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Colleters are widely occurring in eudicots showing relevant taxonomic importance in several families. Nevertheless, there are few records in monocots, restricted to only one description of these glands in Orchidaceae. The genus Oncidium is polyphyletic, currently the subject of taxonomic studies. In this context, the secretory structures can be an important diagnostic character that may help in the...
In 2000 there was an oil spill at the Getúlio Vargas Refinery (REPAR/PETROBRÁS) in Paraná, Brazil. Nearly five years after contamination and the use of bioremediation, a study was carried out to identify the effects of the contaminated soil and the bioremediated soil on the germination and initial growth of Mimosa pilulifera seedlings. The experiment consisted of three treatments: petroleum-contaminated...
We investigated species composition, distribution, and forest structure of understory trees (≥1m height, <10cm diameter at breast height) in two late-successional várzea forests subject to contrasting levels of inundation within the Mamirauá Sustainable Development Reserve, western Brazilian Amazon, and compared it with the overstory flora at the same study sites. In total, 1486 individuals and...
Ipomoea pes-caprae is widespread in pantropical coastal areas along the beach. The aim of this study was to investigate the salinity tolerance level and physiological mechanisms that allow I. pes-caprae to endure abrupt increases in salinity under brief or prolonged exposure to salinity variations. Xylem sap osmolality (X osm ), leaf water relations, gas exchange, and number of produced and...
Disintegration of the Scrophulariaceae due to molecular data resulted in re-circumscriptions, resurrection and new descriptions of families to encompass the monophyletic lineages. In some of these families floral morphological/ontogenetic data, however, are largely missing, as, for example, in Paulowniaceae. This study reveals a set of distinctive features that were up to now unknown in Paulowniaceae:...
Parthenium hysterophorus (Asteraceae) is a noxious plant that is considered one of the most invasive species in the world. We studied changes in the composition of plant species and soil properties related to the invasion of P. hysterophorus in three grassland communities of central Nepal. We collected vegetation and soil data along transects that were established in densely invaded to non-invaded...
The interrelationship between phenological events, climatic factors, periodicity of cambial activity and seasonal production of xylem was examined in Pinus kesiya Royle ex. Gordon growing in sub-tropical wet forest of Meghalaya state, India. Reactivation of dormant cambium occurs after sprouting of new needles during the middle of February. Since the formation of reproductive cones takes place simultaneously...
Asexual reproduction s. l. is widespread in plants and also a basic reproductive mechanism in bryophytes. Today, three types of asexual reproduction are recognized: (1) the asexual reproduction s. str. by regeneration from±specialized caducous organs (leaves, leaf apices, shoots, branches, bulbils) and by production of specialized propagules (gemmae, protonemal brood cells, tubers), (2) fragmentation...
Light, scanning and transmission electron microscopy as well as histochemical reactions were employed to study the leaf structure and secretory activity of Ecballium elaterium, a hairy pharmaceutical perennial common in the Mediterranean region. The amphistomatic leaf has a peculiar structure due to special cells supporting the conductive bundles, a remarkable shortage of mechanical tissue, and the...
Habitat fragmentation often leads to small and isolated plant populations as well as decreased habitat quality. These processes can fundamentally disrupt the interactions between plants and pollinators and decrease reproductive success. This concerns especially self-incompatible, non-clonal species that depend on pollination for successful reproduction.In two rare and endangered heathland plant species,...
Rhizophores – leafless axial organs, which apices are the only sites for root formation – are unique to the Selaginella genus. Both rhizophores and roots are dichotomously branched, forming a multibranch rhizophore–root system. In the examined Selaginella kraussiana, the first dichotomous division of a rhizophore results in the initiation of the twin root meristems, giving rise to the root primordia...
Many plants are adapted to an eroded landscape with a large proportion of virgin soil. Open and disturbed soils are today almost only restricted to agricultural fields with high loads of fertilizers. We conducted a pot experiment in order to investigate growth and nutritional constraints of one calcicole species, Anisantha (syn. Bromus) tectorum, and one calcifuge species, Rumex acetosella, in decalcified...
To understand the effects of grazing on grassland plants sexual and clonal recruitment, we conducted a demographic field investigation of species recruitment along a grazing gradient in the Tibetan alpine grassland. Grazing intensity had significant effects on quantity and diversity of sexual and clonal recruitment. Sexual recruitment increased significantly, but clonal offspring production decreased...
Three Algerian populations of female Pistacia atlantica shrubs were investigated in order to check whether their terpenoid contents and morpho-anatomical parameters may characterize the infraspecific variability. The populations were sampled along a gradient of increasing aridity from the Atlas mountains into the northwestern Central Sahara.As evidenced by Scanning Electron Microscopy, tufted hairs...
Plant growth is driven by the rate of photosynthetic uptake of carbon, the loss of carbon and by allocation of photoassimilates to certain plant compartments, which leads to particular morphologies. Performance, vitality and persistence of a plant are affected by this partitioning process and vice versa. Under harsh climatic conditions such as cold temperature and seasonal drought, perennial plants...
Pollen grains of 30 taxa of the genus Salvia, belonging to sections Salvia, Horminum, Drymosphace, Plethiosphace and Hemisphace from Turkey were examined by light (LM) and scanning electron microscopy (SEM). Detailed pollen morphological characteristics are provided for these taxa. Among the studied taxa, S. verticillata subsp. verticillata from sect. Hemisphace has the smallest pollen grains, and...
The rhizomatous sedge Carex brevicuspis can produce clumping ramets from shortened rhizomes (phalanx) and spreading ramets from elongated rhizomes (guerrilla) to form a combined clonal growth form. In this paper, changes in clonal growth and biomass allocation pattern of C. brevicuspis in response to sedimentation were studied. Four sedimentation depths (0, 3, 6, and 9cm) were applied to 48 ramets...
Fruits formed after different pollination regimes (flowers hand pollinated, unpollinated, and open pollinated) and the seeds obtained were characterized in the wild chilli pepper Capsicum flexuosum Sendtn. Pollen tube development in vivo and ovary growth were also analyzed. Seedless fruits and empty seeds were abundant among the fruits from hand pollinated and open pollinated flowers, while no more...
The architecture of the shoot branching system in Poaceae defines the growth forms within this family. The specific characteristics of the main axis as well as the disposition and characteristics of the lateral shoots determine the main structural variations found among species. In this work, we discuss the set of parameters to be taken into account in describing the vegetative structure of Poaceae...
There is a lack of understanding on factors influencing the occurrence of high species heterogeneity at fine scale in the Brazilian cerrado. Soil is a major determinant of vegetation in the Brazilian cerrado and an important candidate to influence species distribution at fine scales, since soil features vary at very small distances, whereas many environmental variables are relatively homogeneous at...
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