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Auteur A.C. Ellis-Adam |
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Pollination ecology and patch-dependent reproductive success of the rare perennial Gentiana pneumonanthe L. / T. Petanidou in New phytologist, vol. 129 (Année 1995)
[article]
Titre : Pollination ecology and patch-dependent reproductive success of the rare perennial Gentiana pneumonanthe L. Auteurs : T. Petanidou, Auteur ; J. C. M. den Nijs, Auteur ; J. G. B. Oostermeijerand, Auteur ; A.C. Ellis-Adam, Auteur Année de publication : 1995 Article en page(s) : pp. 155-163 Langues : Anglais (eng) Catégories : [Espèces (in biblio)] Gentiana pneumonanthe L.
[Thèmes] Pollinisation, pollen, nectar
[Thèmes] ReproductionRésumé : "The reproductive behaviour of Gentiana pneumonanthe L., a rare plant species in The Netherlands, was studied in a relatively large wet heathland population during summer 1989. The species co-occurred with the grass Molinia caerulea and co-flowered with Erica tetralix and Calluna vulgaris. The flowering period lasted from July to October, peaking in late August to late September. Flowers are protandrous. The species appeared to be self-compatible, but spontaneous self-pollination was strongly limited. Hand-crossing and hand-selfing resulted in the same amount of seed set as in natural pollination. Reproductive success was dramatically reduced late in the season. Pollination was achieved sternotribically by the species Bombus pascuorum, which visited the flowers for nectar. In the study area, three patch types were distinguished: co-dominated by Erica, by Calluna and Erica, and by Molinia, respectively. Frequency of visits to Gentiana was highest in the Erica-patch. However, this did not result in a higher seed set. In the Molinia-patch seed set was reduced. However, in the Molinia-patch the mean number of ovules was greater than in the others (as high as in plants raised indoors and in cross-pollinated plants). Fruits from the Calluna-patch had less ovules than those from the Erica-patch. We conclude that, in this remnant population, Gentiana is not pollination-limited. However, it is likely that in the Molinia-patch geitonogamy is frequent, which may lead to inbreeding depression. The greater number of ovules observed in Molinia-patches may reflect an excess of nutrients available there, relative to the Calluna-patch where there may be reduced water availability." (source : auteurs) Type de publication : périodique Référence biblio : Petanidou T., den Nijs J.-C.-M., Oostermeijerand J.-G.-B., Ellis-Adam A.-C., 1995 - Pollination ecology and patch-dependent reproductive success of the rare perennial Gentiana pneumonanthe L. New phytologist, 129 : 155-163. ID PMB : 72109 Permalink : http://www.cbnbrest.fr/catalogue_en_ligne/index.php?lvl=notice_display&id=72109
in New phytologist > vol. 129 (Année 1995) . - pp. 155-163[article]Exemplaires(0)
Disponibilité aucun exemplaire Variable herkogamy and autofertility in marginal populations of Gentianella germanica in the Netherlands / S.H. Luijten in Folia Geobotanica, vol. 34, n°4 (Année 1999)
[article]
Titre : Variable herkogamy and autofertility in marginal populations of Gentianella germanica in the Netherlands Auteurs : S.H. Luijten, Auteur ; ]. Gerard B. Oostermeijer, Auteur ; A.C. Ellis-Adam, Auteur ; J.H.C.M. (den) Nijs, Auteur Année de publication : 1999 Article en page(s) : pp. 483-496 Langues : Anglais (eng) Catégories : [ZG] Pays-Bas
[Espèces (in biblio)] Gentiana germanica
[Thèmes] Plante à forte valeur patrimoniale
[Thèmes] Pollinisation, pollen, nectarRésumé : "Gentianella germanica (Willd.) Börner, a rare plant species, occurs at the margin of its distribution area in the Netherlands. It is found only in isolated patches of chalk grassland surrounded by intensively-used agricultural land. In 1997 and 1998, we investigated the spatial and temporal separation of anthers and stigma in relation to autofertility. We performed our experiments in one large and two small populations to investigate the possible selection against herkogamy and for increased autofertility in marginal populations with pollination limitation. Dichogamy appeared to be very weak and varied within individuals. Homogamous and protandrous flowers were most frequent. Dichogamy is apparently no effective barrier against self-fertilization in this species. Herkogamy varied significantly between individuals and between populations, and plant and flower size were not correlated with anther-stigma separation. Both observations suggest a genetic basis for herkogamy. Autofertility was generally high in all three populations. Only in one small population was a correlation between autofertility and herkogamy found. In this population, most plants had the stigma positioned above the anthers (mean herkogamy +0.8 mm), while in the other two populations the stigma was positioned mainly in between or below the anthers (mean herkogamy −0.55 mm). In comparison with earlier data from 1991 and 1992, plants in the large population were less herkogamous and more self-fertile in 1998. Since 1993 this population was mown each year one month earlier than usual, leading to dramatic reductions (bottlenecks) in population size. In addition, the early mowing time may have caused a further reduction of the already scarce visitation by pollinating insects. We hypothesize that both adverse conditions may have caused a selection of plants with smaller anther-stigma separation and higher autofertility and thus showing that human influence can have profound effects on the reproductive success and evolution of rare plant species, even if it occurs in the context of nature conservation." (source : auteurs) Type de publication : périodique Référence biblio : Luijten S.-H., Oostermeijer ].-G., Ellis-Adam A.-C., Nijs J.-H.-C.-M. (den), 1999 - Variable herkogamy and autofertility in marginal populations of Gentianella germanica in the Netherlands. Folia Geobotanica, 34 (4) : 483-496. ID PMB : 17464 Permalink : http://www.cbnbrest.fr/catalogue_en_ligne/index.php?lvl=notice_display&id=17464
in Folia Geobotanica > vol. 34, n°4 (Année 1999) . - pp. 483-496[article]Exemplaires(1)
Cote Localisation Disponibilité P0007 Brest Exclu du prêt