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Articles 61 - 79 of 79
Full-Text Articles in Life Sciences
Systematic Anatomy Of Euphorbiaceae Subfamily Oldfieldioideae I. Overview, W. John Hayden
Systematic Anatomy Of Euphorbiaceae Subfamily Oldfieldioideae I. Overview, W. John Hayden
Biology Faculty Publications
The biovulate subfamily Oldfieldioideae of Euphorbiaceae, characterized by spiny pollen, is an otherwise apparently diverse assemblage of mostly Southern Hemisphere trees and shrubs that traditionally have been allied with genera of Phyllanthoideae and Porantheroideae sensu Pax and Hoffmann. Although fairly diverse anatomically, the following structures characterize the subfamily with only a few exceptions: pinnate brochidodromous venation with generally randomly organized tertiary and higher order venation; foliar and petiolar glands absent; unicellular or unbranched uniseriate trichomes; latex absent; mucilaginous epidermis or hypodermis; brachyparacytic stomata; vessel elements with simple perforation plates and alternate, often very small, intervascular pits; thick-walled nonseptate imperforate tracheary …
Stem Development, Medullary Bundles, And Wood Anatomy Of Croton Glandulosus Var. Septentrionalis (Euphorbiaceae), Sheila M. Hayden, W. John Hayden
Stem Development, Medullary Bundles, And Wood Anatomy Of Croton Glandulosus Var. Septentrionalis (Euphorbiaceae), Sheila M. Hayden, W. John Hayden
Biology Faculty Publications
Anatomy and development of vascular tissues in the annual stems of Croton glandulosus var. septentrionalis are described. In primary stages of growth the stem possesses a eustele of bicollateral bundles; international phloem is notably more extensive than the external. In addition to a vascular cambium and secondary xylem that form in the usual fashion, additional cambia add cells to the internal phloem portion of the bicollateral bundles, forming well-marked medullary bundles at the perimeter of the pith. At first, the perimedullary cambial strands produce only internal secondary phloem; later, internal secondary xylem is present, the medullary bundles have an inverted …
A Survey Of Mucilaginous Testa In Chamaesyce, Martha S. Jordan, W. John Hayden
A Survey Of Mucilaginous Testa In Chamaesyce, Martha S. Jordan, W. John Hayden
Biology Faculty Publications
Seeds of Chamaesyce were studied for presence of mucilaginous testa. Samples were selected to represent all major systematic sections within the genus. Observations were made with a dissecting microscope following brief hydration of seeds; additional SEM observations of both intact and fractured dry seeds were made for selected species. With few exceptions, most of Boissier's subsections test positively for seed mucilage; however, mucilage is generally absent in subsections Gymnadeniae and "Sclerophyllae", for which absence of mucilage is regarded as secondary loss from mucilagionus ancestors. Although mucilage production is associated with a well-defined subepidermal layer of macroesclereids, it is …
Notes On Neotropical Amanoa (Euphorbiaceae), W. John Hayden
Notes On Neotropical Amanoa (Euphorbiaceae), W. John Hayden
Biology Faculty Publications
Lectotypes are designated for Amanoa caribaea Krug & Urban and A. guianensis Aublet; presumed syntypes of the latter taxon are shown to be heterogeneous by inclusion of a previously unrecognized species. Four new species of Amanoa are described: A. congesta from French Guiana and northeastern Brazil; A. gracillima from Manaus, Brazil; A. nanayensis from Amazonian Peru and adjacent Colombia and Brazil; and A. neglecta from French Guiana and Surinam. Amanoa sinuosa is proposed as a new name for the later homonym A. robusta Leal. A key to the 13 neotropical species is presented.
Methyl Salicylate Secretory Cells In Roots Of Viola Arvensis And V. Rafinesquii (Violaceae), W. John Hayden, John Clough
Methyl Salicylate Secretory Cells In Roots Of Viola Arvensis And V. Rafinesquii (Violaceae), W. John Hayden, John Clough
Biology Faculty Publications
The aromatic roots of Viola arvensis and V. rafinesquii were studied in order to determine the chemical nature and anatomical localization of their volatile compounds. Gas chromatography and mass spectroscopy revealed a single detectable volatile compound, methyl salicylate. Light microscopy and differential staining with Sudan III indicates the source of this compound to be enlarged secretory cells located in the endodermis, an unusual position for such cells in roots of angiosperms. The secretory endodermal cells are sporadic, but are more frequent in primary roots than in secondary roots and the lower portion of the hypocotyl. It is hypothesized that …
Flueggea Willd, W. John Hayden
Flueggea Willd, W. John Hayden
Biology Faculty Publications
Shrubs to large trees with watery sap. Leaves simple, alternate, pinnately veined, stipulate. Flowers unisexual (and the plants dioecious or rarely monoecious), actinomorphic, in axillary clusters; sepals 4-7, imbricate; petals absent; nectary disk lobed or entire; stamens (3)4-7, alternate with the lobes of floral disk, staminodes absent in pistillate flowers; filaments distinct; ovary superior, on a hypogynous disk, (2)3(4)-carpellate, ovules 2 per cell, hemitropous, pistillode present in staminate flowers; styles distinct and 2-lobed or stigmas sessile. Fruit a capsule or baccate, indehiscent. Seeds 2 per cell. [Hayden, 1987; Sherff, 1939b]
Noteworthy Collections: Virginia, W. John Hayden
Noteworthy Collections: Virginia, W. John Hayden
Biology Faculty Publications
The above collections represent the second record for the state of Virginia, and may well establish the northernmost station for the species in the eastern United States. According to B.L. Lipscomb (Sida 8:320-327. 1980), this Old World weed is spreading throughout the warmer regions of North America. The only previous record of the species from the state is a Fernald specimen from Owl Creek in Virginia Beach. R.W. Tyndall, who found the species in northeastern North Carolina, was unable in 1978 to locate the plant at Fernald's Virginia Beach locality (Castanea 48:277-280. 1983). The Amelia County plants occur in two …
Flora Of Richmond National Battlefield Park, Virginia, W. John Hayden, Melanie Lynn Haskins, Miles F. Johnson, James M. Gardner
Flora Of Richmond National Battlefield Park, Virginia, W. John Hayden, Melanie Lynn Haskins, Miles F. Johnson, James M. Gardner
Biology Faculty Publications
An inventory of the vascular flora of nine of eleven units of Richmond National Battlefield Park was compiled from 1985 to 1987. Each site was visited during the growing season in two to four week intervals; plant species were identified and recorded in the field and/or collected for later study. A total of 761 different species were identified in the surveyed units, and 2487 individual records of species per particular park unit were noted. Twenty-three percent of the flora consists of exotic species, largely from Eurasia. Voucher specimens are housed in the herbaria of the University of Richmond and Virginia …
Ontogeny Of The Cotyledonary Region Of Chamaesyce Maculata (Euphorbiaceae), W. John Hayden
Ontogeny Of The Cotyledonary Region Of Chamaesyce Maculata (Euphorbiaceae), W. John Hayden
Biology Faculty Publications
Development of the cotyledonary region in Chamaesyce maculata is described from germination of the seed through formation of the dense mat of branches which characterize this common weed. The cotyledonary node is trilacunar with split-lateral traces. Epicotyl development is limited to a pair ofleaves ("V-leaves") inserted directly above and decussate to the cotyledons. The two V-leaves are also vascularized by three traces and insertion of these traces relative to the vasculature at the immediately subjacent cotyledonary node is asymmetrical; four of the six V-leaf traces arise on one side of the intercotyledonary plane and two arise on the opposite side. …
The Identity Of The Genus Neowawraea (Euphorbiaceae), W. John Hayden
The Identity Of The Genus Neowawraea (Euphorbiaceae), W. John Hayden
Biology Faculty Publications
On the basis of newly acquired morphological evidence gathered in the course of floristic studies, the monotypic genus Neowawraea Rock is now recognized as a species of Flueggea Willd. and is renamed F. neowawraea W. J. Hayden. Taxonomic documentation presented for F. neowawraea includes an expanded morphological description, a map showing its widely scattered distribution in the Hawaiian Islands to which the species is endemic, and discussions of type specimens, common names, and its extreme rarity. The combination of flowers in pedicellate axillary clusters, the lobed staminate disk, pistillode, extrorse anthers, hemitropous ovules, and, especially, the smoothish dry seeds with …
Anatomy And Affinities Of Penthorum, Melanie Lynn Haskins, W. John Hayden
Anatomy And Affinities Of Penthorum, Melanie Lynn Haskins, W. John Hayden
Biology Faculty Publications
The genus Penthorum L. consists of two species of perennial herbs, P. sedoides of eastern North America and P. chinense of eastern Asia. Penthorum has long been considered intermediate between Crassulaceae and Saxifragaceae. An anatomical study of both species was undertaken to contribute to a better understanding of the relationships of these plants. Prominent anatomical features of Penthorum include: an aerenchymatous cortex and closely-spaced collateral vascular bundles of stems; one-trace unilacunar nodes; brochidodromous venation, rosoid teeth bearing hydathodes, and anomocytic stomata of leaves; angular vessel elements with many-barred scalariform perforation plates and alternate to scattered intervascular pits; thin-walled nonseptate fiber-tracheids; …
Eryngium Prostratum In Central Virginia, W. John Hayden
Eryngium Prostratum In Central Virginia, W. John Hayden
Biology Faculty Publications
While visiting Pocahontas State Park in Chesterfield County, Virginia during the fall of 1984, an unfamiliar blue-flowered plant was observed growing near the upper reaches of Swift Creek Lake. This proved to be Eryngium prostratum Nuttall ex DC., a species common near bodies of water in the southeast U.S. While several standard floras include Virginia in the distribution of this plant (Fernald 1950, Gleason 1952, Gleason & Cronquist 1963, Radford et al 1968, Godfrey & Wooten 1981), the only counties for which it is recorded in Harvill et al (1981) are along the extreme southern border of the state, i.e., …
Wood Anatomy And Relationships Of Neowawraea (Euphorbiaceae), W. John Hayden, Dorthe S. Brandt
Wood Anatomy And Relationships Of Neowawraea (Euphorbiaceae), W. John Hayden, Dorthe S. Brandt
Biology Faculty Publications
Wood anatomy of three specimens of Neowawraea phyllanthoides Rock, a rare and endangered member of Euphorbiaceae endemic to the Hawaiian Islands, is described and compared with woods of other genera of subfamily Phyllanthoideae. Neowawraea has often been associated or synonymized with Drypetes Vahl. Wood of Neowawraea is diffuse porous, perforation plates are simple, imperforate tracheary elements are thin-walled septate fiber-tracheids, rays are heterocellular and crystalliferous, and axial xylem parenchyma is restricted to a few scanty paratracheal and terminal cells. In several respects these results differ from earlier published descriptions of the wood of this taxon; these earlier descriptions are shown …
Wood Anatomy And Relationships Of Betula Uber, W. John Hayden, Sheila M. Hayden
Wood Anatomy And Relationships Of Betula Uber, W. John Hayden, Sheila M. Hayden
Biology Faculty Publications
Wood anatomy of Betula uber (Ashe) Fernald is described and compared with woods of other birches belonging to series Humiles and series Costatae. Anatomically, wood of B. uber is typical of birches in general. On the basis of pore size and frequency, fiber characteristics, axial xylem parenchyma distribution, and absence of aggregate rays, it is argued that B. uber is properly classified in series Costatae. Resolution of its relationships within series Costatae is not apparent from wood data.
Systematics And Palynology Of Picrodendron Further Evidence For Relationship With The Oldfieldioideae (Euphorbiaceae), W. John Hayden, W. T. Gillis, D. E. Stone, C. R. Broome, G. L. Webster
Systematics And Palynology Of Picrodendron Further Evidence For Relationship With The Oldfieldioideae (Euphorbiaceae), W. John Hayden, W. T. Gillis, D. E. Stone, C. R. Broome, G. L. Webster
Biology Faculty Publications
Although known to botanical science for 285 years, the genus Picrodendron Planchon has been poorly understood for most of this time. The most pervasive problem has been that of discerning familial relationships, and there have been additional difficulties in typifying the generic name (Hayden & Reveal, 1980) and in distinguishing its three nominate species. This paper provides a systematic treatment for Picrodendron and demonstrates its relationships with Euphorbiaceae subfam. Oldfieldioideae Kohler & Webster as evidenced by data on gross morphology, palynology, anatomy, and cytology.
Curatorial News From The University Of Richmond Herbarium, W. John Hayden
Curatorial News From The University Of Richmond Herbarium, W. John Hayden
Biology Faculty Publications
The Department of Biology at the University of Richmond maintains a herbarium of approximately 15,000 specimens. In an effort to make this collection better known to Virginia botanists, this note describes some recent curatorial improvements upon the UR Herbarium and outlines its contents.
Jamaican Blue-Green Algae Collections Of J.C. Strickland, W. John Hayden
Jamaican Blue-Green Algae Collections Of J.C. Strickland, W. John Hayden
Biology Faculty Publications
Professor John C. Strickland (1915-1980) devoted much of his life to teaching biology, botany, and phycology at the University of Richmond. Throughout his academic career he maintained a keen interest in the Myxophyceae, or blue-green algae, studying their culture, cytology, and taxonomy (Drouet & Strickland, 1942; Strickland, 1940, 1946). Most of his collections of these and other algae were made in Virginia and are housed in the herbarium maintained by the Department of Biology, University of Richmond. However, he also made four trips to Jamaica in the years 1966-1971 before his health deteriorated to the extent that field work, and …
Proposal For The Conservation Of The Generic Name Picrodendron Grisebach (1859) Against Picrodendron Planchon (1846) (Euphorbiaceae), W. John Hayden, James L. Reveal
Proposal For The Conservation Of The Generic Name Picrodendron Grisebach (1859) Against Picrodendron Planchon (1846) (Euphorbiaceae), W. John Hayden, James L. Reveal
Biology Faculty Publications
Petalacte has been in continuous use for this genus of 1-3 species since proposed by D. Don. The only exception was Lessing's misuse of Petalolepis Cassini, from which he excluded the two original Australian species and substituted two from S. Africa. Lessing was not followed by later authors.T he genus was recently revised by Lundgren (in Bot. Notiser 127: 119-124. 1974) and this revision may be consulted for full references.
Comparative Anatomy And Systematics Of Picrodendron, Genus Incertae Sedis, W. John Hayden
Comparative Anatomy And Systematics Of Picrodendron, Genus Incertae Sedis, W. John Hayden
Biology Faculty Publications
This study of the vegetative anatomy of Picrodendron and some of its putative relatives has been undertaken in order better to understand its natural relationships. Despite the number of anatomical studies in the literature (Jadin, 1901; Solereder, 1908; Boas, 1913; Webber, 1936; Heimsch, 1942; Record & Hess, 1943; Metcalfe & Chalk, 1950), our information on the anatomy of Picrodendron is still incomplete· for example, nodal and petiolar anatomy has apparently never been described. Furthermore, with the exception of Record and Hess (1943), who discussed Picrodendron in a family by itself, other anatomists have compared Picrodendron only with members of Simaroubaceae, …