The Flowers in Extant Basal Angiosperms and Inferences on Ancestral Flowers

Endress, Peter K.

doi:10.1086/321919

Cited by 260 publications

(283 citation statements)

References 139 publications

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“…6A, C, D) and presumably triploid endosperm; an orthotropous ovule with cup-shaped outer integument (Endress and Igersheim 2000; Yamada et al 2001); and successive microsporogenesis (Furness et al 2002). These and other morphological characters (Doyle and Endress 2000;Sampson 2000;Endress 2001;Hesse 2001) indicate that monotypic Amborellaceae may be highly apomorphic, an obvious reminder that basal taxa need not be plesiomorphic taxa.…”

Section: The Distribution Of Female Gametophyte Types In Anitagrade Amentioning

confidence: 98%

Modularity of the Angiosperm Female Gametophyte and Its Bearing on the Early Evolution of Endosperm in Flowering Plants

Friedman

Williams

2003

Evolution

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Abstract. The monosporic seven-celled/eight-nucleate Polygonum-type female gametophyte has long served as a focal point for discussion of the origin and subsequent evolution of the angiosperm female gametophyte. In Polygonumtype female gametophytes, two haploid female nuclei are incorporated into the central cell, and fusion of a sperm cell with the binucleate central cell produces a triploid endosperm with a complement of two maternal and one paternal genomes, characteristic of most angiosperms. We document the development of a four-celled/four-nucleate female gametophyte in Nuphar polysepala (Engelm.) and infer its presence in many other ancient lineages of angiosperms. The central cell of the female gametophyte in these taxa contains only one haploid nucleus; thus endosperm is diploid and has a ratio of one maternal to one paternal genome. Based on comparisons among flowering plants, we conclude that the angiosperm female gametophyte is constructed of modular developmental subunits. Each module is characterized by a common developmental pattern: (1) positioning of a single nucleus within a cytoplasmic domain (pole) of the female gametophyte; (2) two free-nuclear mitoses to yield four nuclei within that domain; and (3) partitioning of three uninucleate cells adjacent to the pole such that the fourth nucleus is confined to the central region of the female gametophyte (central cell). Within the basal angiosperm lineages Nymphaeales and Illiciales, female gametophytes are characterized by a single developmental module that produces a four-celled/four-nucleate structure with a haploid uninucleate central cell. A second pattern, typical of Amborella and the overwhelming majority of eumagnoliids, monocots, and eudicots, involves the early establishment of two developmental modules that produce a sevencelled/eight-nucleate female gametophyte with two haploid nuclei in the central cell. Comparative analysis of ontogenetic sequences suggests that the seven-celled female gametophyte (two modules) evolved by duplication and ectopic expression of an ancestral Nuphar-like developmental module within the chalazal domain of the female gametophyte. These analyses indicate that the first angiosperm female gametophytes were composed of a single developmental module, which upon double fertilization yielded a diploid endosperm. Early in angiosperm history this basic module was duplicated, and resulted in a seven-celled/eight-nucleate female gametophyte, which yielded a triploid endosperm with the characteristic 2:1 maternal to paternal genome ratio.

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Section: The Distribution Of Female Gametophyte Types In Anitagrade Amentioning

confidence: 98%

Modularity of the Angiosperm Female Gametophyte and Its Bearing on the Early Evolution of Endosperm in Flowering Plants

Friedman

Williams

2003

Evolution

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“…Reviews on floral structure with different foci and various new results were provided by Endress (2001Endress ( , 2004), Endress Doyle (2009), andDoyle &Endress (2011). In the last two articles we used parsimony to reconstruct (optimize) the course of evolution of characters on two reference trees, chosen to represent the range of current phylogenetic results.…”

Section: Ancestral Traits and Specializations In The Flowers Of The Bmentioning

confidence: 99%

“…It is spiral in Amborella and Austrobaileyales, but simple whorled or more commonly complex whorled in Nymphaeales (Endress, 2001;Schneider & al., 2003). In complex whorled flowers there is often multiple Version of Record doubling of organ positions, in which case the merism changes from whorl to whorl.…”

Section: Ancestral Traits Of (Living) Angiosperms (Figs 2-7)mentioning

confidence: 99%

“…In Nuphar double positions begin in the second whorl of the inner tepals (the inner tepals have sometimes been called "petals", since they have features like the petals of eudicots). It is important to emphasize that the flowers of all Nymphaeaceae so far investigated have a complex whorled, not spiral phyllotaxis (Endress, 2001;Schneider & al., 2003). Thus descriptions of Nymphaeaceae in textbooks and Floras as having spiral parts are erroneous.…”

Section: Version Of Recordmentioning

confidence: 99%

“…-Floral phyllotaxis is spiral throughout (Endress, 2001). The perianth is more or less caducous, with a well developed abscission zone at the base of each tepal.…”

Section: Version Of Recordmentioning

confidence: 99%

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Ancestral traits and specializations in the flowers of the basal grade of living angiosperms

Endress

Doyle

2015

TAXON

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New morphological and phylogenetic data prompt us to present an updated review of floral morphology and its evolution in the basal ANITA grade of living angiosperms, Chloranthaceae, and Ceratophyllum. Floral phyllotaxis is complex whorled in Nymphaeales and spiral in Amborella and Austrobaileyales. It is unresolved whether phyllotaxis was ancestrally whorled or spiral, but if it was whorled, the whorls were trimerous. The flowers are probably ancestrally bisexual because in most families with unisexual flowers these flowers exhibit rudiments of the opposite sex. Carpels are largely ascidiate and the closure line is short, either transverse or longitudinal. A style is usually absent or, if present, generally short and not plicate. Angiospermy (carpel sealing) is by secretion, rather than postgenital fusion, except in large‐flowered Nymphaeales and in Illicium, correlated with unusual fruits. Carpels with a single, median, pendent ovule are probably plesiomorphic. Chloranth‐ aceae and Ceratophyllaceae have an unsettled phylogenetic position, but in some phylogenetic analyses they form a clade, which may be sister to the remaining mesangiosperms (Magnoliidae, monocots, eudicots). This position is supported by their carpel characters, which are similar to those of the ANITA grade and different from those of most other mesangiosperms.

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Ancestral traits and specializations in the flowers of the basal grade of living angiosperms

Endress

Doyle

2015

Taxon

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New morphological and phylogenetic data prompt us to present an updated review of floral morphology and its evolution in the basal ANITA grade of living angiosperms, Chloranthaceae, and Ceratophyllum. Floral phyllotaxis is complex whorled in Nymphaeales and spiral in Amborella and Austrobaileyales. It is unresolved whether phyllotaxis was ancestrally whorled or spiral, but if it was whorled, the whorls were trimerous. The flowers are probably ancestrally bisexual because in most families with unisexual flowers these flowers exhibit rudiments of the opposite sex. Carpels are largely ascidiate and the closure line is short, either transverse or longitudinal. A style is usually absent or, if present, generally short and not plicate. Angiospermy (carpel sealing) is by secretion, rather than postgenital fusion, except in largeflowered Nymphaeales and in Illicium, correlated with unusual fruits. Carpels with a single, median, pendent ovule are probably plesiomorphic. Chloranth aceae and Ceratophyllaceae have an unsettled phylogenetic position, but in some phylogenetic analyses they form a clade, which may be sister to the remaining mesangiosperms (Magnoliidae, monocots, eudicots). This position is supported by their carpel characters, which are similar to those of the ANITA grade and different from those of most other mesangiosperms.

show abstract

The Flowers in Extant Basal Angiosperms and Inferences on Ancestral Flowers

Cited by 260 publications

References 139 publications

Modularity of the Angiosperm Female Gametophyte and Its Bearing on the Early Evolution of Endosperm in Flowering Plants

Modularity of the Angiosperm Female Gametophyte and Its Bearing on the Early Evolution of Endosperm in Flowering Plants

Ancestral traits and specializations in the flowers of the basal grade of living angiosperms

Ancestral traits and specializations in the flowers of the basal grade of living angiosperms

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