The existence of pollination syndromes and the degree of specialization in these systems are still discussed. Three examples from the tropical mountain communities in the Bamenda Highlands (Cameroon) show that a detailed knowledge of plants and their visitors and pollinator behavioral studies are necessary before evolutionary hypotheses can be formulated., Michael Bartoš, Eliška Padyšáková, Štěpán Janeček., and 7 barev. fot.
New insights into the evolutionary processes that have fostered the species richness of Cape flora (in particular genome duplication) have been gained by Czech researchers during the last few years. Pleasures and pains of botanical research in this world biodiversity hotspot are summarized. and Jan Suda.
Giant rosettes are ones of the most striking features of the vegetation in the high tropical Andes, with Coespeletia moritziana reaching the highest altitudes up to 4,600 m a.s.l. Different from other giant rosettes, this species grows on rock outcrops with poorly developed soils and where water availability may be limited. Two questions are addressed in this study: How does this species respond in terms of water relations to maintain favorable gas-exchange conditions? Considering that adult plants rely on a water-reserving central pith, how do early stages respond to this environment’s extreme conditions? Water relations and gas-exchange studies were carried out on juveniles, intermediate and adult C. moritziana plants during wet and dry seasons in Páramo de Piedras Blancas at 4,200 m a.s.l. Adult plants maintained higher leaf water potentials (ΨL) during the wet season, however, no differences between stages were found for the dry season. Minimum dry season ΨL were never near the turgor loss point in any of the stages. Juveniles show a more strict stomatal control during the dry season to maintain a favorable water status. Net photosynthesis significantly decreased in intermediate and juvenile stages from wet to dry seasons. Our results suggest that
C. moritziana resists more extreme conditions compared to other Andean giant rosettes., F. Rada, A. Azócar, A. Rojas-Altuve., and Obsahuje bibliografii
Během několika uplynulých tisíciletí byla Malta – středozemní souostroví se dvěma velkými a osídlenými ostrovy Malta a Gozo – zcela zbavena lesních porostů s převládajícími borovicí halebskou (Pinus halepensis) a dubem cesmínovitým (Quercus ilex). Současná planě rostoucí vegetace, tvořená převážně degradovanou macchií a formacemi garrigue a frygana, je nyní soustavně potlačována šířícími se sídlišti. Nicméně stojí za to navštívit Maltu a seznámit se s její květenou vyšších rostlin, čítající kolem jednoho tisíce druhů (včetně 36 zajímavých orchidejí), a to zejména v časně jarním období., Malta, a Mediterranean archipelago with two large, inhabited islands, has over the past millennia been totally deprived of forests with dominating Allepo Pine (Pinus halepensis) and Holm Oak (Quercus ilex). The contemporary wild vegetation – mainly of degraded macchia, garrigue and phrygana is being continuously suppressed by urban explosion. Nevertheless, the Maltese wild flora numbering around 1,000 vascular plant species (including 36 interesting orchids) makes a visit to Malta worthwhile, particularly in the early springtime., and Jan Čeřovský.
This area in Central Bohemia is characterized by predominantly limestone bedrock and fully-developed karstic phenomena – the main reasons for its high botanical di - versity and occurrence of many rare and endangered species. In the center of the area, well-developed broad-leaved forests are found, as well as xerothermophilous non-forest vegetation. At the borders of the area, acidophilous, basiphilous and serpen - tinophilous plants occur on non-calcareous rocks (e. g. slates, basaltoids, picrites). and Pavel Špryňar.
Rostlinný hormon auxin je známý jako regulátor prodlužování stonku a (ne)aktivity postranních pupenů. Ve skutečnosti ale dokáže mnohem více. Ovšem jen za předpokladu, že se ho správné množství vyskytuje ve správném místě a čase. Příjem auxinového signálu zajišťují receptory uvnitř buňky i na jejím povrchu., The plant hormone auxin is a long-known regulator of shoot elongation and auxiliary bud (in)activity. But there is much more about it – if the right amount of auxin appears at the right place and time. The auxin signal is perceived by both intracellular and surface receptors., and Jiří Libus.
Although it has been generally reported that carnivorous plants of the genus Nepenthes are not very selective about their prey, the new studies have shown that the genus is under a strong selective pressure to specialize in certain prey. Moreover, novel nutrient sequestration strategies have recently been described, including leaf litter and faeces utilization. Thus the genus Nepenthes is a new and illustrative example of adaptive radiation with regard to nitrogen sequestration strategy. and Andrej Pavlovič.