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1
Content available Phyllotactic pattern formation in early stages of cactus ontogeny
100%
Gola E. M.
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nr 4
271-279
EN
Representatives of the family Cactaceae are characterized by a wide range of phyllotaxis. To assess the origin of this diversity, early stages of phyllotactic pattern formation were examined in seedlings. The analysis of the sequence of areole initiation revealed intertribal differences. In seedlings from the Trichocereeae (Gymnocalycium, Rebutia) and Notocacteae (Parodia) tribes, two opposite cotyledonal areoles developed as the first elements of a pattern. Usually, next pair of areoles was initiated perpendicularly to cotyledonal areoles, starting the decussate pattern. This pattern was subsequently transformed into bijugate or into simple spiral phyllotaxis. In seedlings from the Cacteae tribe (Mammillaria and Thelocactus), cotyledonal areoles were never observed and the first areoles always appeared in the space between cotyledons. It was either areole pair (mainly in Mammillaria), starting a decussate pattern, or a single areole (mainly in Thelocactus) quickly followed by areoles spirally arranged, usually in accordance with the main Fibonacci phyllotaxis. Differences in the initial stages of pattern formation do not fully explain the phyllotaxis diversity in mature cacti. Only two, the most common phyllotactic patterns occurred in the early development of studied seedlings, i.e. the main Fibonacci and the decussate pattern. Discrepancy in the range of phyllotactic spectra in seedlings and in mature plants suggests that phyllotaxis diversity emerges during further plant growth. Initial phyllotactic transformations, occurring already in the very early stages, indicate great plasticity of cactus growth and seem to support the hypothesis of the ontogenetic increase of phyllotaxis diversity due to transformations.
2
Morphogenesis at the shoot apex of Huperzia Bernh.
88%
Gola E. M.
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nr Suppl.1
3
Content available Diversity of phyllotaxis in land plants in reference to the shoot apical meristem structure
63%
Gola E. M. , Banasiak A.
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tom 85
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nr 4
EN
Regularity and periodicity in the arrangements of organs in all groups of land plants raise questions about the mechanisms underlying phyllotactic pattern formation. The initiation of the lateral organs (leaves, flowers, etc.), and thus, their spatio-temporal positioning, occurs in the shoot apical meristem (SAM) and is related to the structure and organogenic activity of the meristem. In this review, we present some aspects of the diversity and stability of phyllotactic patterns in the major lineages of land plants, from bryophytes to angiosperms, in which SAM structures differ significantly. In addition, we discuss some of the possible mechanisms involved in the formation of the recurring arrangement of the lateral organs.
4
Content available Vascular structure contributes to shoot sectoriality in Selaginella kraussiana
63%
Gola E. M. , Jernstedt J. A.
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nr 3
EN
Selaginella species are characterized by regular anisotomous dichotomous divisions of the shoot apical meristem, giving rise to two new axes (branches) which differ in size. A vital process is the formation of vascular connections, which enables continuous communication and consequent functional and developmental integration of a plant during branching. Here, we present the sequence of developmental changes in the vascular system of Selaginella kraussiana related to dichotomous branching. Stem vasculature in Selaginella kraussiana consists of two meristeles which change in arrangement during shoot development. Using dye tracers, we documented developmental functional isolation of meristeles associated with the specific structure of the stelar system, which results in a spatiotemporal sectoriality of the shoot. We discuss sectoriality in terms of possible significance for shoot development.
5
Content available It is worth checking old data – validation of Asplenium onopteris L. presence in the most northeastern sites in Europe (Sudetes, SW Poland)
51%
Szczesniak E. , Gola E. M. , Jedrzejczyk I.
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2017
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tom 86
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nr 4
EN
In Poland, isolated serpentine rocks are exclusive habitats of some Asplenium species, reaching here their north or northeastern border range. One of them was Asplenium onopteris, a diploid European species native to Mediterranean and Atlantic areas. Since the nineteenth century, Polish out-of-range sites of A. onopteris have been quoted in literature without critical verification. Thus, to verify occurrence of this species in Poland, we analyzed the nuclear DNA content and micromorphological features as well as critically reviewed the literature data. We proved that all individuals from Polish populations resembling A. onopteris were tetraploids and should be classified as A. adiantum-nigrum. In addition, we validated a taxon silesiacum reported as co-occurring with A. onopteris. The proposed diagnostic features are insufficient to indisputably delimit this taxon, and distinguishing it as a separate unit is not justified. Analyses of the DNA content revealed also the presence of a triploid A. ×centovallense, a new hybrid for Polish flora.
6
Content available Lykopodiofity Polski Lycopodiales, Selaginellales, Isoëtales
51%
Szczesniak E. , Gola E. M. , Zenkteler E.
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2023
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tom 110
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