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Ontogeny Of The Cotyledonary Region Of Chamaesyce Maculata (Euphorbiaceae), W. John Hayden Nov 1988

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 Apr 1987

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 Feb 1987

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 Dec 1985

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., …


University Of Richmond Herbarium, W. John Hayden Nov 1984

University Of Richmond Herbarium, W. John Hayden

Biology Faculty Publications

The Department of Biology at the University of Richmond, Richmond, Virginia, maintains an herbarium of approximately 15,000 specimens. Although recently assigned the acronym URV, this collection has not yet been included in Index Herbariorum and, consequently, few botanists outside of Virginia are aware of its existence. This note provides a brief account of the history of URV, a summary of its contents, and a short bibliography of works pertaining to the collection.


Wood Anatomy And Relationships Of Neowawraea (Euphorbiaceae), W. John Hayden, Dorthe S. Brandt Oct 1984

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 Mar 1984

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.


Curatorial News From The University Of Richmond Herbarium, W. John Hayden Jan 1984

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.


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 Jan 1984

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.


Jamaican Blue-Green Algae Collections Of J.C. Strickland, W. John Hayden Jul 1983

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 Aug 1980

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 Jan 1977

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, …