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Himantormia lugubris has developed special growth strategies as well as special structures on morphology and anatomy. H. lugubris, an antarctic endemic, is distributed on the islands of the northern maritime Antarctic and along the Antarctic Peninsula (to the Argentine Islands). The rock surface is colonized by a thin web of hyphae from which a horizontal thallus emerges resembling a dark crustose...
Samples of the foliose epiphytic lichen Hypogymnia physodes were incubated with 0, 100, 500, and 1000 μM KCl solution for up to 120 min. K was absorbed by H. physodes only in single replicates of the most highly concentrated solutions. Otherwise a release of K of up to 26 μmol g −1 d. wt. was observed. This can be attributed to the low affinity of K for the cation exchange sites in lichen...
An architectural analysis of the genus Grindelia was carried out, and seven different models were established. Differences in architecture between North American and South American species are pointed out, and their possible taxonomic implications are indicated. The different architectural models are compared with those exhibited by related genera.
In addition to the green leaves, commonly considered as the primary sources of photosynthate production, higher plants can potentially use almost all vegetative and reproductive structures to perform photosynthetic CO 2 assimilation. Green leaves, stems and green sterile flower organs, optimized for light harvesting and photosynthetic performance, are characterized by net photosynthetic assimilation...
Changes of vertical arrangements in plant communities cause changes in processes and habitat parameters such as microclimate, nutrient cycles, arthropod behaviour and others. Therefore the description and analysis of structural dynamics is the basis for investigations at the level of processes. With VESTA (VErtical vegetation STructure Analysis), an improved photographic method of analysing vertical...
While net CO 2 exchange (NP) of leaves has been studied extensively in vascular epiphytes, there is little information on NP of reproductive structures. Since such information is important to evaluate the magnitude of investment in reproduction, we conducted a study with fruits of nine species of epiphytic orchids on Barro Colorado Island, Panama. Irrespective of the photosynthetic pathway...
In this paper we describe the pollen developmental processes in Picea asperata Mast. by means of cytochemical and ultrastructural methods, with an emphasis on starch grains, callose dynamics and the ultrastructure of prothallial cells. It was observed that microsporogenesis and pollen development of Picea asperata proceeded from early March to late April. The meiosis of pollen mother cells (PMC) was...
Diurnal courses of net CO 2 uptake rate, stomatal conductance (g S ), maximum photochemical efficiency of PSII (Fv/Fm) and apparent photosynthetic electron transport rate (ETR) were measured in Quercus ilex and Phillyrea latifolia in a holm oak forest throughout the seasons of the year. These measurements were complemented with response curves of photosynthetic rates to PPFD and CO...
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