| 1. |
- Crane, Peter Robert, et al.
(författare)
-
Water lilies, loss of woodiness, and model systems
- 2020
-
Ingår i: Proceedings of the National Academy of Sciences. ; 117, s. 9674-9676
-
Tidskriftsartikel (refereegranskat)abstract
- The delicate necklace of threaded petals from the tomb of Rameses II, mid-nineteenth century glasshouses built for the newly discovered Victoria amazonica, and Monet’s giant canvases in the Mus´ee de l’Orangerie all testify to a deep human attraction to waterlilies: beguiling plants with showy flowers that seem toarise nymph-like out of the mud. Like orchids, cacti, succulents, and carnivorous plants, water lilies have a dedicated band of horticulturalists devoted to growing and exploring their endless variety. The late nineteenth century craze for water lilies that attracted Monet was fueled by one such enthusiast, Joseph Bory Latour-Marliac, who developed hardy waterlily cultivars with dazzling new flower colors ranging from “delicate yellow to fuscia and deep red.” Nymphaea thermarum, the focus of the recent paper by Povilus et al., is another unusual water lily variant. The smallest water lily known, N. thermarum was discovered and described in the late 1980s. Endemic to hot spring lakes in the Albertine Rift Valley of Rwanda, now, just a few decades after its discovery,it appears to be extinct in the wild.
|
|
| 2. |
- Friis, Else Marie, et al.
(författare)
-
Melloniflora, a new extinct multiparted flower from the Early Cretaceous of Virginia
- 2020
-
Ingår i: International journal of plant sciences. - : University of Chicago Press. - 1058-5893 .- 1537-5315. ; 181, s. 887-897
-
Tidskriftsartikel (refereegranskat)abstract
- remise of research. The Puddledock mesofossil flora from Virginia is the richest source for studying structurally preserved plant fossils in the Early Cretaceous Potomac Group sequence. Together with other mesofossil floras from the Potomac Group and also from Portugal, it is key for direct assessment of the structure, relationships, and reproductive biology of early angiosperms. In this study, a new multiparted floral structure from the Puddledock locality is analyzed, and its phylogenetic relationships are discussed.Methodology. The fossil was extracted from unconsolidated clays and sands through sieving in water. Adhering sediment was removed using HF and HCl followed by rinsing in water. External and internal features were studied using scanning electron microscopy and synchrotron radiation X-ray tomographic microscopy. Phylogenetic analyses were carried out by adding the features of the fossil flower to an existing morphological data set for extant angiosperms.Pivotal results. A new taxon, Melloniflora virginiensis gen. et sp. nov., is established on the basis of a small multiparted floral structure that has several series of free stamens (ca. 50) and carpels (21) borne on a flattened receptacle. Stamens have a broad, short base, and dehiscence is introrse. Ovules are borne in two rows on either side of the ventral suture of the carpels. Abundant secretory cells occur in all tissues. Melloniflora is related to extant early-diverging members of the Magnoliales but also has features found among extant taxa of other early-diverging angiosperm lineages such as Austrobaileyales.Conclusions. Melloniflora adds to the knowledge of plants related to extinct magnoliids from the Early Cretaceous. It shows a combination of features not seen in any extant taxon. Melloniflora contributes to the evidence of considerable extinct diversity at an early stage in angiosperm evolution, especially among clades that today are represented by only a few relatively species-poor lineages.
|
|
| 3. |
- Friis, Else Marie, et al.
(författare)
-
Multiparted, apocarpous flowers from the Early Cretaceous of eastern North America and Portugal
- 2020
-
Ingår i: Fossil Imprint. - Prague : Czech National Museum. - 2533-4069 .- 2533-4050. ; 76, s. 279-296
-
Tidskriftsartikel (refereegranskat)abstract
- Three new genera, Atlantocarpus, Lambertiflora and Mugideiriflora, are described from the Early Cretaceous of North America and Portugal based on floral structures with multicarpellate and apocarpous gynoecia that have been studied using scanning electron microscopy and synchrotron radiation X-ray tomographic microscopy. Lambertiflora and Mugideiriflora have numerous perianth parts in several series, as well as many stamens and many carpels borne on a short conical receptacle. Atlantocarpus has many carpels arranged spirally on an elongated receptacle. Perianth and stamens are not preserved in Atlantocarpus, but scars of two sizes at the base of the receptacle indicate the presence of several series of tepals and stamens. Phylogenetic assessment of the three new genera indicates close relationships with members of extant Austrobaileyales, which is also favoured by the apparently ascidiate carpels of Atlantocarpus. However, the phylogenetic signal is not strong and the fossils also share many features with magnoliid angiosperms. Fully secure resolution of their relationships is hampered by lack of information of critical floral features in the fossil material, the constellation of likely plesiomorphic characters that they exhibit, and inadequate knowledge of character homologies and character evolution among extant taxa. There is also the broader concern about whether phylogenetic patterns can be reliably inferred for the earliest phases of angiosperm evolution based solely on a depauperate assemblage of extant taxa given extensive extinction over the last 100 million years. The new genera add to growing evidence of diverse extinct angiosperms with multiparted flowers during the Early Cretaceous that have a variety of relationships to extant ANA-grade angiosperms and magnoliids.
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Herrera, Fabiany, et al.
(författare)
-
Reconstructing Krassilovia mongolica supports recognition of a new and unusual group of Mesozoic conifers
- 2020
-
Ingår i: PLOS ONE. - : PLoS. - 1932-6203. ; 15:1, s. 1-21
-
Tidskriftsartikel (refereegranskat)abstract
- Previously unrecognized anatomical features of the cone scales of the enigmatic Early Cretaceous conifer Krassilovia mongolica include the presence of transversely oriented paracytic stomata, which is unusual for all other extinct and extant conifers. Identical stomata arepresent on co-occurring broad, linear, multiveined leaves assigned to Podozamites harrisii, providing evidence that K. mongolica and P. harrisii are the seed cones and leaves of the same extinct plant. Phylogenetic analyses of the relationships of the reconstructed Krassilovia plant place it in an informal clade that we name the Krassilovia Clade, which also includes Swedenborgia cryptomerioides–Podozamites schenkii, and Cycadocarpidium erdmanni–Podozamites schenkii. All three of these plants have linear leaves that are relatively broad compared to most living conifers, and that are also multiveined with transversely oriented paracytic stomata. We propose that these may be general features of the Krassilovia Clade. Paracytic stomata, and other features of this new group, recall features of extant and fossil Gnetales, raising questions about the phylogenetic homogeneity of the conifer clade similar to those raised by phylogenetic analyses of molecular data.
|
|
