Comparative Pollen Morphology of the Mainland African Genera of Myristicaceae (Cephalosphaera, Coelocaryon, Pycnanthus, and Scyphocephalium)

Walker, James W.; Walker, Audrey G.

doi:10.2307/2442653

Cited by 9 publications

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“…Apertural exine section, showing very reduced exine (both nexine and sexine) and acetolysis-resistant intine beneath. Walker, 1974b), as previously stated by Kuprianova (1967), based on observation of immature myristicaceous pollen tetrads. Fig.…”

Section: Tessmannii a Species That Smith Recognizedmentioning

confidence: 74%

“…An attempt was made to study pollen from as many collections annotated by A. C. Smith or cited by him (Smith, 1938(Smith, , 1950 Walker (1974aWalker ( , b, 1976, and Walker and Walker (1979, 1980, 1981. Voucher specimens as well as our palynological accession numbers (each preceded by a "P") are listed after the generic pollen descriptions for each collection studied, and pollen examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) is indicated.…”

Section: Tessmannii a Species That Smith Recognizedmentioning

confidence: 99%

“…Methods-Pollen was prepared for light microscopy (LM), SEM, and TEM by methods previously outlined (Walker and Walker, 1980). SEM ofpollen sections was accomplished using pollen that was initially acetolyzed at room temperature for 1 hr and then washed.…”

Section: Tessmannii a Species That Smith Recognizedmentioning

confidence: 99%

“…The first paper in this series (Walker and Walker, 1981) dealt with the Madagascan Myristicaceae, while our second paper (Walker and Walker, 1980) was concerned with the mainland African Myristicaceae. The first paper in this series (Walker and Walker, 1981) dealt with the Madagascan Myristicaceae, while our second paper (Walker and Walker, 1980) was concerned with the mainland African Myristicaceae.…”

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confidence: 99%

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Comparative Pollen Morphology of the American Myristicaceous Genera Otoba, Iryanthera, and Osteophloeum

Walker¹,

Walker²

1983

American Journal of Botany

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Section: Tessmannii a Species That Smith Recognizedmentioning

confidence: 74%

Section: Tessmannii a Species That Smith Recognizedmentioning

confidence: 99%

Section: Tessmannii a Species That Smith Recognizedmentioning

confidence: 99%

mentioning

confidence: 99%

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Comparative Pollen Morphology of the American Myristicaceous Genera Otoba, Iryanthera, and Osteophloeum

Walker¹,

Walker²

1983

American Journal of Botany

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“…A rather intriguing phenomenon is the appearance of columellate exines which, according to widespread consensus, seem to have evolved from a granular, or completely compact exine in parallel in various evolutionary lines. The cooccurrence of columellaless and columellate exines for example in the Nymphaeaceae, Canellaceae, and in various genera of the Annonaceae (Le Thomas 1980/ 81) and Myristicaceae (Walker andWalker 1980, 1981) would imply the multiple transition from the noncolumellate to the columellate state. Even if one invokes the functional aspect-storage of substances involved in sporophytic self-incompatibility reactions in the inter-columellar space (Heslop-Harrison 1976)-a completely independent and multiple origin ofthe columellate structure is difficult to understand since its origin would appear as a preadaptation for the evolution of an-in this case-sporophytic self-incompatibility system.…”

Section: Functional Constraintsmentioning

confidence: 99%

Genetic Variation in Endemic and Widespread Plant Species

Soltis¹,

Soltis²

1991

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ABSTRAcrParallelism as one of the forms of biological similarity is investigated in the light of recent findings from developmental and molecular biology. From the organismic point of view, functional constraints and evolutionary canalization are well established as causes of parallelism. To these may be added, from the molecular perspective, (a) erratic activations of repressed genes; (b) activations of alternative pathways under the influence ofhomoeotic genes; and (c) horizontal gene transfer, for which a simple mechanism is proposed. The control of gene expression through the action oftransposable elements, reversible to some degree, appears to be an evolutionarily important and frequent phenomenon, which may account for many cases formerly interpreted as losses or irreversible changes of genes. It is suggested that this mechanism, which seems to be optimized in angiosperms, may account for the great evolutionary plasticity of this plant group. It may also provide an explanation for so-called reversals which appear as artifacts of character analyses and are biologically barely explicable. Events of horizontal gene transfer, creative for evolution but disturbing for classification, appear less frequent, or otherwise the structure of the taxonomic hierarchy would not be perceptible. Increasing knowledge in the fields of molecular and developmental biology tends to blur the borderline between homology, homoiology, parallelism, and perhaps convergence, phenomena formerly thought to be more or less distinct.

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Floral Development in Myristica (Myristicaceae)

Armstrong

Tucker

1986

American J of Botany

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Myristica fragrans and M. malabarica are dioecious. Both staminate and pistillate plants produce axillary flowering structures. Each pistillate flower is solitary, borne terminally on a short, second‐order shoot that bears a pair of ephemeral bracts. Each staminate inflorescence similarly produces a terminal flower and, usually, a third‐order, racemose axis in the axil of each pair of bracts. Each flower on these indeterminate axes is in the axil of a bract. On the abaxial side immediately below the perianth, each flower has a bracteole, which is produced by the floral apex. Three tepal primordia are initiated on the margins of the floral apex in an acyclic pattern. Subsequent intercalary growth produces a perianth tube. Alternate with the tepals, three anther primordia arise on the margins of a broadened floral apex in an acyclic or helical pattern. Usually two more anther primordia arise adjacent to each of the first three primordia, producing a total of nine primordia. At this stage the floral apex begins to lose its meristematic appearance, but the residuum persists. Intercalary growth below the floral apex produces a columnar receptacle. The anther primordia remain adnate to the receptacle and grow longitudinally as the receptacle elongates. Each primordium develops into an anther with two pairs of septate, elongate microsporangia. In pistillate flowers, a carpel primordium encircles the floral apex eventually producing an ascidiate carpel with a cleft on the oblique apex and upper adaxial wall. The floral ontogeny supports the morphological interpretation of myristicaceous flowers as trimerous with either four‐sporangiate anthers or monocarpellate pistils.

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Comparative Pollen Morphology of the Mainland African Genera of Myristicaceae (Cephalosphaera, Coelocaryon, Pycnanthus, and Scyphocephalium)

Cited by 9 publications

References 0 publications

Comparative Pollen Morphology of the American Myristicaceous Genera Otoba, Iryanthera, and Osteophloeum

Comparative Pollen Morphology of the American Myristicaceous Genera Otoba, Iryanthera, and Osteophloeum

Genetic Variation in Endemic and Widespread Plant Species

Floral Development in Myristica (Myristicaceae)

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