Shoot Development in Members of an Ancient Aquatic Angiosperm Lineage, Ceratophyllaceae: A New Interpretation Facilitates Comparisons with Chloranthaceae
<i>Ceratophyllum</i> is an ancient and phylogenetically isolated angiosperm lineage. Comparisons between <i>Ceratophyllum</i> and other angiosperms are hampered by uncertainty in inferring organ homologies in this genus of specialized aquatics. Interpretation of shoot morphol...
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| Format: | Article |
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MDPI AG
2022-06-01
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| Series: | Symmetry |
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| Online Access: | https://www.mdpi.com/2073-8994/14/7/1288 |
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| author | Dmitry D. Sokoloff Elena S. El Margarita V. Remizowa |
| author_facet | Dmitry D. Sokoloff Elena S. El Margarita V. Remizowa |
| author_sort | Dmitry D. Sokoloff |
| collection | DOAJ |
| description | <i>Ceratophyllum</i> is an ancient and phylogenetically isolated angiosperm lineage. Comparisons between <i>Ceratophyllum</i> and other angiosperms are hampered by uncertainty in inferring organ homologies in this genus of specialized aquatics. Interpretation of shoot morphology is especially problematic in <i>Ceratophyllum</i>. Each node has several leaf-like appendages interpreted as verticillate leaves, modified parts of one and the same leaf or parts of two leaves under decussate phyllotaxis. Vegetative branches are axillary, but reproductive units (interpreted as flowers or inflorescences) are commonly viewed as developing from collateral accessory buds. We studied shoot development in <i>Ceratophyllum submersum</i>, <i>C. tanaiticum</i>, and <i>C. demersum</i> using scanning electron microscopy to clarify shoot morphology and branching patterns. Our data support the idea that the phyllotaxis is essentially decussate with appendages of stipular origin resembling leaf blades. We conclude that a leaf axil of <i>Ceratophyllum</i> possesses a complex of two serial buds, the lower one producing a vegetative branch and the upper one developing a reproductive unit. The reproductive unit is congenitally displaced to the subsequent node, a phenomenon known as concaulescence. Either member of the serial bud complex may be absent. There is a theory based on a synthesis of molecular and morphological data that Chloranthaceae are the closest extant relatives of <i>Ceratophyllum.</i> Serial buds and concaulescence are known in <i>Hedyosmum</i> (Chloranthaceae). Our new interpretation facilitates morphological comparisons between <i>Hedyosmum</i> and <i>Ceratophyllum</i>. |
| first_indexed | 2024-03-09T05:48:14Z |
| format | Article |
| id | doaj.art-87e4dca0069a4450a3bb937338e39b38 |
| institution | Directory Open Access Journal |
| issn | 2073-8994 |
| language | English |
| last_indexed | 2024-03-09T05:48:14Z |
| publishDate | 2022-06-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Symmetry |
| spelling | doaj.art-87e4dca0069a4450a3bb937338e39b382023-12-03T12:19:10ZengMDPI AGSymmetry2073-89942022-06-01147128810.3390/sym14071288Shoot Development in Members of an Ancient Aquatic Angiosperm Lineage, Ceratophyllaceae: A New Interpretation Facilitates Comparisons with ChloranthaceaeDmitry D. Sokoloff0Elena S. El1Margarita V. Remizowa2Faculty of Biology, M.V. Lomonosov Moscow State University, 119234 Moscow, RussiaFaculty of Biology, M.V. Lomonosov Moscow State University, 119234 Moscow, RussiaFaculty of Biology, M.V. Lomonosov Moscow State University, 119234 Moscow, Russia<i>Ceratophyllum</i> is an ancient and phylogenetically isolated angiosperm lineage. Comparisons between <i>Ceratophyllum</i> and other angiosperms are hampered by uncertainty in inferring organ homologies in this genus of specialized aquatics. Interpretation of shoot morphology is especially problematic in <i>Ceratophyllum</i>. Each node has several leaf-like appendages interpreted as verticillate leaves, modified parts of one and the same leaf or parts of two leaves under decussate phyllotaxis. Vegetative branches are axillary, but reproductive units (interpreted as flowers or inflorescences) are commonly viewed as developing from collateral accessory buds. We studied shoot development in <i>Ceratophyllum submersum</i>, <i>C. tanaiticum</i>, and <i>C. demersum</i> using scanning electron microscopy to clarify shoot morphology and branching patterns. Our data support the idea that the phyllotaxis is essentially decussate with appendages of stipular origin resembling leaf blades. We conclude that a leaf axil of <i>Ceratophyllum</i> possesses a complex of two serial buds, the lower one producing a vegetative branch and the upper one developing a reproductive unit. The reproductive unit is congenitally displaced to the subsequent node, a phenomenon known as concaulescence. Either member of the serial bud complex may be absent. There is a theory based on a synthesis of molecular and morphological data that Chloranthaceae are the closest extant relatives of <i>Ceratophyllum.</i> Serial buds and concaulescence are known in <i>Hedyosmum</i> (Chloranthaceae). Our new interpretation facilitates morphological comparisons between <i>Hedyosmum</i> and <i>Ceratophyllum</i>.https://www.mdpi.com/2073-8994/14/7/1288axillary branchingCeratophyllales<i>Ceratophyllum</i>Chloranthalesevolutionflower |
| spellingShingle | Dmitry D. Sokoloff Elena S. El Margarita V. Remizowa Shoot Development in Members of an Ancient Aquatic Angiosperm Lineage, Ceratophyllaceae: A New Interpretation Facilitates Comparisons with Chloranthaceae Symmetry axillary branching Ceratophyllales <i>Ceratophyllum</i> Chloranthales evolution flower |
| title | Shoot Development in Members of an Ancient Aquatic Angiosperm Lineage, Ceratophyllaceae: A New Interpretation Facilitates Comparisons with Chloranthaceae |
| title_full | Shoot Development in Members of an Ancient Aquatic Angiosperm Lineage, Ceratophyllaceae: A New Interpretation Facilitates Comparisons with Chloranthaceae |
| title_fullStr | Shoot Development in Members of an Ancient Aquatic Angiosperm Lineage, Ceratophyllaceae: A New Interpretation Facilitates Comparisons with Chloranthaceae |
| title_full_unstemmed | Shoot Development in Members of an Ancient Aquatic Angiosperm Lineage, Ceratophyllaceae: A New Interpretation Facilitates Comparisons with Chloranthaceae |
| title_short | Shoot Development in Members of an Ancient Aquatic Angiosperm Lineage, Ceratophyllaceae: A New Interpretation Facilitates Comparisons with Chloranthaceae |
| title_sort | shoot development in members of an ancient aquatic angiosperm lineage ceratophyllaceae a new interpretation facilitates comparisons with chloranthaceae |
| topic | axillary branching Ceratophyllales <i>Ceratophyllum</i> Chloranthales evolution flower |
| url | https://www.mdpi.com/2073-8994/14/7/1288 |
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