Progress and problems in the assessment of flower morphology in higher-level systematics

Endress, Peter K.; Matthews, Merran L.

doi:10.1007/s00606-011-0576-2

Cited by 33 publications

(29 citation statements)

References 181 publications

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“…Petals tend to be free in most taxa. Endress & Matthews (2012) mention several exceptions where petals are fused and usually connected by a hypanthium (cf. Ronse De Craene 2010).…”

Section: Perianth In the Rosidsmentioning

confidence: 99%

Origin and evolution of petals in angiosperms

Craene

2013

Plecevo

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REVIEWBackground and aims -The term 'petal' is loosely applied to a variety of showy non-homologous structures, generally situated in the second whorl of a differentiated perianth. Petaloid organs are extremely diverse throughout angiosperms with repeated derivations of petals, either by differentiation of a perianth, or derived from staminodes. The field of evo-devo has prompted re-analysis of concepts of homology and analogy amongst petals. Here the progress and challenges in understanding the nature of petals are reviewed in light of an influx of new data from phylogenetics, morphology and molecular genetics. Method and results -The complex web of homology concepts and criteria is discussed in connection to the petals, and terminology is subsequently defined. The variation and evolution of the perianth is then reviewed for the major clades of angiosperms. From this pan-angiosperm variation, we highlight and discuss several recurrent themes that complicate our ability to discern the evolution of the petal. In particular we emphasise the importance of developmental constraint, environmental stimuli, interrelationship between organs and cyclic patterns of loss and secondary gain of organs, and the development of a hypanthium or corona.Conclusions -A flexible approach to understanding 'petals' is proposed requiring consideration of the origin of the floral organ (stamen-derived or tepal-derived, or other), the functional role (sepaloid or petaloid organs), evolutionary history of the organismal lineage, and consideration of developmental forces acting on the whole flower. The variety and complex evolutionary history of the perianth may necessitate the exploration of petal development within phylogenetically quite restricted groups, combining data from morphology with evo-devo.

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“…Petals tend to be free in most taxa. Endress & Matthews (2012) mention several exceptions where petals are fused and usually connected by a hypanthium (cf. Ronse De Craene 2010).…”

Section: Perianth In the Rosidsmentioning

confidence: 99%

Origin and evolution of petals in angiosperms

Craene

2013

Plecevo

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“…In the other two genera of Paracryphiales, Paracryphia and Sphenostemon, clear petals are absent (Dickison and Baas 1977;Endress 2008). One wonders whether the systematic position of Quintinia in campanulids is correct, especially as the feature of bitegmic versus unitegmic ovules is otherwise macrosystematically very stable (Endress 2011a(Endress , 2011bEndress and Matthews 2012).…”

Section: Friis Et Al-extant Quintinia and Fossil Silvianthemum And Bmentioning

confidence: 99%

Floral Structure of Extant Quintinia (Paracryphiales, Campanulids) Compared with the Late Cretaceous Silvianthemum and Bertilanthus

Friis

Pedersen

Endress

2013

International Journal of Plant Sciences

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Flowers of extant Quintinia are described in detail on the basis of field observations and serial microtome sections and compared with flowers of the Late Cretaceous Silvianthemum suecicum and Bertilanthus scanicus on the basis of new analyses of the fossil material. The analyses of both extant and fossil material also include synchrotron-based X-ray tomographic microscopy. The study shows that Quintinia and Silvianthemum/Bertilanthus have more features in common than previously recognized and strongly reinforces their earlier assumed close relationships. Among important characters linking the three genera are similar secretory hairs on the floral surface and pedicel; short sepals; free, quincuncial petals; broad anthers with small pollen sacs; 4-aperturate pollen (in Silvianthemum and Quintinia); postgenital union of the 3-4 apocarpous styles (in Silvianthemum and Quintinia); connection of the apocarpous carpel parts with the floral base; downward tapering ovary and locule(s); placentation on incomplete septa; and flask-shaped epidermal cells with a thin and long papilla on the carpels. Features observed in Quintinia, particularly the presence of bitegmic ovules and free petals, suggest that the apparent phylogenetic position with extant Paracryphiales (campanulids) needs further analysis. Bitegmic ovules are not known from other Paracryphiales or campanulids, and the presence of free petals is unusual in campanulids. Flowers of extant Quintinia are described in detail on the basis of field observations and serial microtome sections and compared with flowers of the Late Cretaceous Silvianthemum suecicum and Bertilanthus scanicus on the basis of new analyses of the fossil material. The analyses of both extant and fossil material also include synchrotron-based X-ray tomographic microscopy. The study shows that Quintinia and Silvianthemum/Bertilanthus have more features in common than previously recognized and strongly reinforces their earlier assumed close relationships. Among important characters linking the three genera are similar secretory hairs on the floral surface and pedicel; short sepals; free, quincuncial petals; broad anthers with small pollen sacs; 4-aperturate pollen (in Silvianthemum and Quintinia); postgenital union of the 3-4 apocarpous styles (in Silvianthemum and Quintinia); connection of the apocarpous carpel parts with the floral base; downward tapering ovary and locule(s); placentation on incomplete septa; and flask-shaped epidermal cells with a thin and long papilla on the carpels. Features observed in Quintinia, particularly the presence of bitegmic ovules and free petals, suggest that the apparent phylogenetic position with extant Paracryphiales (campanulids) needs further analysis. Bitegmic ovules are not known from other Paracryphiales or campanulids, and the presence of free petals is unusual in campanulids.

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“…Phylogenetics based on molecular markers have redefined circumscriptions in Linnaeeae (Landrein et al, 2012;Wang et al, 2015), and it is also important to characterize these new groups morphologically (Endress & Matthews, 2012).…”

Section: Nectary Morphologymentioning

confidence: 99%

Structure, ultrastructure and evolution of floral nectaries in the twinflower tribe Linnaeeae and related taxa (Caprifoliaceae)

Landrein

Prenner

2016

Bot. J. Linn. Soc.

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Linnaeeae is a small tribe of Caprifoliaceae consisting of six genera and c. 20 species. In Linnaeeae, floral nectaries are located on the corolla-filament-tube and nectar is produced from unicellular glandular hairs. We studied 23 taxa using scanning electron microscopy (SEM), light microscopy (LM) and transmission electron microscopy (TEM) and found two distinct nectary morphologies, zonate and gibbous types, and two distinct types of glandular hair, clavate and smooth base types. Plesiomorphic characters associated with the nectary and identified in the tribe include hypocrateriform corollas, dichogamous flowers, zonate nectaries, wet papillate stigmas, vestigial nectary disc and smooth pollen grains. Apomorphic characters include bilabiate corollas, homogamous flowers, bulging nectaries, dry papillate stigmas and echinulate pollen grains. The nectary structure is similar in Vesalea and Linnaea and differs from the rest of the tribe, in accordance with recent phylogenetic results. Nectar secretion is typically granulocrine with subcuticular accumulation of nectar, which we compared with the secretion in multicellular hairs of Adoxa moschatellina. The cuticle on the hair becomes detached from the cell wall and large subcuticular spaces filled with nectar are formed. Nectar is probably released in areas with a thin cuticle. In Zabelia, the smooth basal part of the hair could help to build up the hydrostatic pressure.

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Progress and problems in the assessment of flower morphology in higher-level systematics

Cited by 33 publications

References 181 publications

Origin and evolution of petals in angiosperms

Origin and evolution of petals in angiosperms

Floral Structure of Extant Quintinia (Paracryphiales, Campanulids) Compared with the Late Cretaceous Silvianthemum and Bertilanthus

Structure, ultrastructure and evolution of floral nectaries in the twinflower tribe Linnaeeae and related taxa (Caprifoliaceae)

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