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Pheromonal interactions between cordate gametophytes of the lady fern, A. filix-femina, were assayed using a protocol typically used for detecting water-soluble pheromones such as antheridiogen. Three week-old, cordate gametophytes were transferred from multispore cultures grown on nutrient agar to agar containing extracts from a previous generation of gametophytes (treatment) and to fresh nutrient agar (control). Three weeks after transfer, fifty gametophytes were examined from treatment and control plates. Each gametophyte was measured for size (area) and shape (circularity) and scored for number of antheridia and archegonia. Treatment gametophytes were significantly smaller, less circular, had fewer archegonia, and possessed antheridia more often than control gametophytes, a pattern consistent with known antheridiogen effects on gametophytes of transitional morphology and sensitivity. The experiment was repeated using gametophytes that were six weeks old at time of transfer to treatment and control plates. Treatment gametophytes in the second experiment did not differ significantly in size (area) or length from control gametophytes; however treatment gametophytes were more circular and possessed greater widths and length : width ratios, deeper notches, and fewer archegonia. We present a model in which one or more phytochemicals released by cordate gametophytes increase rates of anticlinal division in the apical meristem. The possibilities that the substances involved are phytohormones involved in the development of a notch meristem and cordate morphology in the source gametophyte, and that antheridiogen may be involved, are explored.
The spores of the following genera of Polypodiaceae growing in northwest Argentina were analyzed: Campyloneurum, Microgramma, Pecluma, Phlebodium, Pleopeltis and Polypodium. The study involved analyses of herbarium material using light microscopy and scanning electron microscopy. The spores are monolete, 40–90 μm in major equatorial diameter, eliptic to oblong in polar view and plane to concave-convex in equatorial view. The exospore ranges from 2–5 μm thick, is apparently double-layered, with a verrucate or tuberculate surface that is usually perforated. The perispore ranges from 0.3–1 μm thick, is apparently single-layered, attached to the exospore, perforated, and generally smooth or in some cases micro-ornamented. Most of the taxa analyzed have globules on the surface. These are single or associated in masses and irregularly distributed. Characteristics such as size, shape and exospore and perispore sculpture allow us to differentiate among some of the genera as well as recognize species groups. Microgramma, Campyloneurum, Pecluma, Pleopeltis and Polypodium have verrucate spores whereas those of Phlebodium are tuberculate.
Spore germination of four rupicolous taxa of Asplenium (A. adiantum-nigrum. var. adiantum-nigrum, A. adiantum.nigrum. var. silesiacum, A. septentrionale subsp. septentrionale and A. ruta-muraria. subsp. ruta-muraria) was determined after 1, 6, and 12 months of storage in Eppendorf tubes (dry storage) or on agar plates (wet storage) at −20, 5 and 20°C. In general, technique and temperature factors and the moisture-temperature interaction, had a significant effect on germination percentage. In all cases, except for A. ruta-muraria, germination percentage was maintained in wet and dry storage, but in the dry storage method percent germination was higher. These results indicate some capacity of Asplenium spores to withstand desiccation, and that ecological requirements of species may influence spore viability and should be taken into account when designing spore conservation programs. Spores of A. ruta-muraria yielded better results in wet storage. In dry storage its response was different from that of the other three taxa. Wet storage at −20°C killed all or most spores of all taxa.
An ethnobotanical study of the pteridophytes used by the Tacana and Huaorani indigenous groups from Amazonian forests of Bolivia and Ecuador is presented. Twenty-four useful species, eleven for Bolivia and fourteen for Ecuador, are reported. The only species used by both groups is Cyathea pungens. Most of the recorded uses (76%) are medicinal. Whereas the Tacana use most medicinal pteridophytes by external administration, to heal wounds, swelling, boils, and as eyewash, the Huaorani use them by internal administration, mainly to cure diarrhea, stomachache, body-pain, toothache, and colds. Three species are recorded for veterinary use (12%), to heal wounds and to expel intestinal parasites of domestic animals. Tree-ferns were widely used by all the interviewed informants.
This study was designed to evaluate selected physiological responses of Salvinia minima to copper (Cu2 ) concentrations of 0.06 (control), 1.0, 2.0, 2.5, and 3.0 mg l−1. The plants were grown under laboratory conditions of 25 ± 2°C, a light intensity of 120 μmol m−2 s−1, and a 14-h photoperiod. After seven days of exposure to the Cu, Salvinia growth decreased gradually with an increase in Cu concentration resulting in a significant decline at 3.0 mg l−1Cu. Similar results were obtained after 14 days of exposure. However, calculating growth using fresh weight showed a significant decline at 2.5 and 3.0 mg l−1. After 14 days exposure, CO2 assimilation decreased as the Cu concentration increased in the growth media. This decrease in CO2 assimilation coincided with a similar decrease in photosynthetic pigments. Uptake of Cu significantly increased with the increase of Cu concentration in the growth media. This study demonstrated the potential of Salvinia to remediate Cu in concentrations 100 times what is currently found in freshwater environments.
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