Morphology and Orientation of the Embryo of Isoetes

Motte, Charles La

doi:10.1093/oxfordjournals.aob.a083498

Cited by 19 publications

(14 citation statements)

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“…The results of this study are in substantial agreement with conclusions reached by LaMotte (1936) on the basis of his study of the embryology of Isoetes.…”

Section: -Isupporting

confidence: 91%

A Comparative Study of Stigmarian Appendages and Isoetes Roots

Stewart

1947

American J of Botany

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“…The results of this study are in substantial agreement with conclusions reached by LaMotte (1936) on the basis of his study of the embryology of Isoetes.…”

Section: -Isupporting

confidence: 91%

A Comparative Study of Stigmarian Appendages and Isoetes Roots

Stewart

1947

American J of Botany

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“…The reserve function is even morphologically reinforced in some Selaginella species by a septum separating the gametophyte from the bulk of the megaspore contents (Robert ; Gifford and Foster ). Similar nutrient stores are observed in the megaspores of other lineages of free‐sporing heterosporous plants (Campbell ; La Motte ; Schneider and Pryer ). Although it remains to demonstrate experimentally that these reserves provide an advantage for establishment of new sporophytes under natural conditions, the mechanisms that would create an advantage for Selaginella —greater survival rate and better etiolation response under litter, shade or competitive pressure (Leishman and Westoby ) —are no different to those acting in seeds, where such effects have been abundantly demonstrated (Salisbury ; Leishman and Westoby ; Rees ; Milberg et al.…”

Section: Discussionsupporting

confidence: 74%

The adaptive value of heterospory: Evidence from Selaginella

Petersen

Burd

2018

Evolution

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Heterospory was a pivotal evolutionary innovation for land plants, but it has never been clear why it evolved. We used the geographic distributions of 114 species of the heterosporous lycophyte Selaginella to explore the functional ecology of microspore and megaspore size, traits that would be correlated with many aspects of a species' regeneration niche. We characterized habitats at a global scale using leaf area index (LAI), a measure of foliage density and thus shading, and net primary productivity (NPP), a measure of growth potential. Microspore size tends to decrease as habitat LAI and NPP increase, a trend that could be related to desiccation resistance or to filtration of wind-borne particles by leaf surfaces. Megaspore size tends to increase among species that inhabit regions of high LAI, but there is an important interaction with NPP. This geographical pattern suggests that larger megaspores provide an establishment advantage in shaded habitats, although in open habitats, where light is less limiting, higher productivity of the environment seems to give an advantage to species with smaller megaspores. These results support previous theoretical arguments that heterospory was originally an adaptation to the increasing height and density of Devonian vegetative canopies that accompanied the diversification of vascular plants with leaves.

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“…In the former, a massive foot forms from all hypobasal derivatives as in the psilophytes (Bierhorst 1971), ophioglossaceous ferns (Foster 1964), Equisetum (Campbell 1928), and subterranean schizaeaceous ferns (Bierhorst 1975) and provides nourishment for the embryo before it gains nutritional independence. In the latter, fewer early formative derivatives contribute to the foot compared to the larger absorptive shoot and root as in the Marattiales (Campbell 1894;Brebner 1896) or protocorm as in lycophytes (Treub 1890;Bruchmann 1912;LaMotte 1937). As in exoscopic ferns, C. richardii lacks an absorptive shoot and quickly emerges from the gametophyte; however, as in endoscopy, an early RAM forms alongside a relatively smaller foot.…”

Section: Embryology Reflects the Mechanical Constraints Imposed By Thmentioning

confidence: 99%

“…During foot proliferation, early vacuolization and associated cell expansion results in increased surface area that facilitates nutrient uptake (Ward 1954). Unlike endoscopic lycophytes, where foot expansion pushes and re-orients the embryonic axis in the gametophyte (Treub 1890;Bruchmann 1912;LaMotte 1937), foot expansion in Ceratopteris anchors the embryonic axis in its pre-established orientation.…”

Section: Embryology Reflects the Mechanical Constraints Imposed By Thmentioning

confidence: 99%

Embryology of Ceratopteris richardii (Pteridaceae, tribe Ceratopterideae), with emphasis on placental development

Johnson

Renzaglia

2008

J Plant Res

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This comprehensive study of early embryology in Ceratopteris richardii combines light microscopy with the first ultrastructural evaluation of any pteridophyte embryo. Emphasis is placed on ontogeny of the foot and placental transfer cells. The embryology of C. richardii shares many similarities with that of other polypodiacious ferns while exhibiting distinctive division patterns. Formative embryonic stages have been reconstructed into three-dimensional models for ease of interpretation. The zygote divides perpendicular to the gametophyte plane and anterioposterior axis. This division establishes a prone embryological habit that maximizes rapid independent establishment of a leaf-root axis in a cordate gametophyte. After the formation of a globular eight-celled stage, initials of the first leaf, and root and shoot apical meristems are defined early by discrete formative divisions. Concomitantly, the foot expands and differentiates to transport nutrients from the gametophyte for the developing embryonic organs. Transfer cell wall ingrowth deposition begins in the gametophyte placental cells before the adjacent sporophyte cells just after the eight-celled stage. These observations provide an anatomical framework for future comparative developmental genetic studies of embryogenesis in free-sporing plants.

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Morphology and Orientation of the Embryo of Isoetes

Cited by 19 publications

References 0 publications

A Comparative Study of Stigmarian Appendages and Isoetes Roots

A Comparative Study of Stigmarian Appendages and Isoetes Roots

The adaptive value of heterospory: Evidence from Selaginella

Embryology of Ceratopteris richardii (Pteridaceae, tribe Ceratopterideae), with emphasis on placental development

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