On the Stem Apex, Leaf Initiation and Early Leaf Ontogeny in Filicalean Ferns

Bierhorst, David W.

doi:10.1002/j.1537-2197.1977.tb15712.x

Cited by 110 publications

(55 citation statements)

References 12 publications

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“…bostonensis with histological information and conditional probability modelling, to provide a robust analysis of cell lineage patterns in a fern. Despite previous suggestions that sectorial chimaeras cannot occur in ferns because shoot growth occurs from a single apical initial (Bierhorst, 1977), we confirm that shoots, fronds and pinnae of N. exaltata each develop from single initials. We further demonstrate that shoots and fronds develop iteratively, whereas pinnae are determinate.…”

Section: Introductioncontrasting

confidence: 99%

“…For example, surface examination of the shoot apex of numerous species reveals a tetrahedral apical cell with three cutting faces (Bierhorst, 1977) similar to that seen in N. exaltata (Fig. 2).…”

Section: Discussionmentioning

confidence: 63%

“…For 30 years, debates ensued about the existence, number and role of apical initial(s), and about the role of zonation within the apex (for a review, see White and Turner, 1995). The current consensus is that fern shoots, fronds and pinnae develop from one or two apical initials, with the actual number varying between species (Bierhorst, 1977;Hill, 2001;Pray, 1960). This consensus is derived from the examination of cleared shoot apices, histological sections and sequential surface imprints.…”

Section: Introductionmentioning

confidence: 99%

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Sector analysis and predictive modelling reveal iterative shoot-like development in fern fronds

2011

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SUMMARYPlants colonized the terrestrial environment over 450 million years ago. Since then, shoot architecture has evolved in response to changing environmental conditions. Our current understanding of the innovations that altered shoot morphology is underpinned by developmental studies in a number of plant groups. However, the least is known about mechanisms that operate in ferns -a key group for understanding the evolution of plant development. Using a novel combination of sector analysis, conditional probability modelling methods and histology, we show that shoots, fronds ('leaves') and pinnae ('leaflets') of the fern Nephrolepis exaltata all develop from single apical initial cells. Shoot initials cleave on three faces to produce a pool of cells from which individual frond apical initials are sequentially specified. Frond initials then cleave in two planes to produce a series of lateral merophyte initials that each contributes a unit of three pinnae to half of the mediolateral frond axis. Notably, this iterative pattern in both shoots and fronds is similar to the developmental process that operates in shoots of other plant groups. Pinnae initials first cleave in two planes to generate lateral marginal initials. The apical and marginal initials then divide in three planes to coordinately generate the determinate pinna. These findings impact both on our understanding of fundamental plant developmental processes and on our perspective of how shoot systems evolved.

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Section: Introductioncontrasting

confidence: 99%

Section: Discussionmentioning

confidence: 63%

Section: Introductionmentioning

confidence: 99%

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Sector analysis and predictive modelling reveal iterative shoot-like development in fern fronds

2011

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“…46), similar to the packets of cells recorded on the surface of certain fern stem apices (see e.g. Bierhorst, 1977: Osmunda regalis), but there is no evidence of a single apical cell. Further the apex appears as a continuation of an erect axis, there being no indication of the circinate vernation that characterizes a number of zosterophylls (Niklas & Banks, 1990;Lyon & Edwards, 1991).…”

Section: Ground Tissue Systemssupporting

confidence: 62%

Cells and tissues in the vegetative sporophytes of early land plants

Edwards

1993

New Phytologist

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SUMMARY Remarkable preservation in coalified and pennineralized fossils from Upper Silurian and Lower Devonian sediments deposited some 420 to 390 million years ago provides insight into the major anatomical innovations associated with the early stages in the colonization of the land by higher plants. Using uniformitarian principles, such information, combined with gross morphology, can then be used to reconstruct the pioneers as growing, metabolizing and reproducing organisms, as well as allowing assessment of affinity, although apart from the lycophytes, they have no close relationship with extant groups. In considering vascular tissues, diversity is exemplified by descriptions of the metaxylem in protosteles of Zosterophyllopsida and Drepanophycopsida (putative lycophytes), of Psilophyton (Trimerophytopsida), of the Rhyniaceae (including Rhynia gwynnevaughanii, certain Taeniocrada spp., Sennicaulis) and of Cooksonia pertoni, a Lower Devonian representative of the organization found in the oldest pteridophyte‐like land plants. Aglaophyton major is included as a plant with bryophyte‐like vascular tissues in a branching sporophyte with cuticle, stomata and intercellular space system typical of the homoiohydric tracheophyte. In all water‐conducting cells, interpretation of the primary and secondary wall results from comparisons involving the anatomy and chemistry of extant examples and an understanding of taphonomic processes. Phloem is only rarely preserved and usually identified from its position around the xylem. In contrast, dermal features are better known, because of penetration of the resilient cuticle between epidermal cells. They appear conservative. Thus stomata with two guard cells look remarkably similar to extant forms in surface view, and by consideration of their relationship with surrounding epidermal cells and of extent of cuticularization, seem to have operated in a similar way to those in certain mosses and ferns. Cuticular ornamentation (papillae, striations) and epidermal outgrowths (unicellular and multicellular) are described and their adaptive significance conjectured. Ground tissue systems are best preserved in Rhynie Chert permineralizations where zonation of the cortex is tentatively related to photosynthetic and structural roles. The latter function is also attributed to thick‐walled, outer cortical cells recorded in many zosterophylls and in Psilophyton, although the chemical nature of the walls themselves remains equivocal. Problems of identification of roots in plants possessing axial organization with exarch xylem, and in leafy plants with smooth lateral branching systems are briefly addressed. Finally axis apices in Rhynia givynne‐vaughanii and sections showing stages in the maturation of Asteroxylon stems are described from the Rhynie Chert.

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“…The apical meristem of this plant is based upon an apical cell with three cutting faces (10); this cell divides to give rise to daughter cells which continue to undergo mitosis. Thus all of the cells in the body of the rhizome are derived ultimately from the apical cell.…”

Section: The Fern Assaymentioning

confidence: 99%

Screening Aquatic Ecosystems for Mutagens with Fern Bioassays

Klekowski¹

1978

Environmental Health Perspectives

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Recent researches on the royal fern, Osmunda regalis, have documented a high incidence of postzygotic mutational damage in a population growing in a river heavily poiluted with paper processing wastes, whereas genetic studies of nearby populations in nonpoHluted environments failed to detect mutational damage. Intensive genetic and cytogenetic studies of mutation in 0. regalis indicates that natural populations of homosporous ferns may be useful in situ bioassay systems for monitoring the presence of mutagens in aquatic ecosystems. Since these organisms are long-lived perennials with an ontogenetic system which stores mutational damage, they can be manipulated to give an integrated estimate of mutational damage for specified blocks of time (in units of years). Thus, the fern bioassay may be an inexpensive means of detecting both chronic low dose and episodic high dose inputs of mutagenic pollutants into aquatic ecosystems.The fern mutagen bioassay is based upon the detection of numerous categories of post-zygotic mutation load in natural fern populations. The frequency of sporophytic and embryonic lethals, leaf or root mutations, auxotrophic gametophytic mutations as well as numerous phenotypic alterations of gametophyte morphology can be routinely detected and quantified. In addition, various two-break chromosome aberrations (paracentric inversions, reciprocal translocations and ring chromosomes) can be readily screened for in the spore mother cells of many homosporous ferns.

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On the Stem Apex, Leaf Initiation and Early Leaf Ontogeny in Filicalean Ferns

Cited by 110 publications

References 12 publications

Sector analysis and predictive modelling reveal iterative shoot-like development in fern fronds

Sector analysis and predictive modelling reveal iterative shoot-like development in fern fronds

Cells and tissues in the vegetative sporophytes of early land plants

Screening Aquatic Ecosystems for Mutagens with Fern Bioassays

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