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Articles 61 - 90 of 98
Full-Text Articles in Botany
Spiderwort Is Vnps Wildflower Of The Year, W. John Hayden
Spiderwort Is Vnps Wildflower Of The Year, W. John Hayden
Biology Faculty Publications
The VNPS 2008 Wildflower of the Year (WOY) is spiderwort (Tradescantia virginiana). This herbaceous perennial plant occurs throughout much of the eastern portion of the U.S. and is widespread in Virginia. Spiderwort blooms from April to July. The small flowers occur in clusters at the ends of the stems, atop several elongate bracts. Flowers have three petals that range from purple to rose or, rarely, white. Densely hairy stamens provide, perhaps, the easiest way to recognize spiderworts. Also, stalks of spent flowers droop below the flower cluster yielding an aspect reminiscent of spindly spider legs.
2008 Wildflower Of The Year: Virginia Spiderwort, Tradescantia Virginiana, W. John Hayden
2008 Wildflower Of The Year: Virginia Spiderwort, Tradescantia Virginiana, W. John Hayden
Biology Faculty Publications
Spiderwort is an herbaceous perennial that arises from a cluster of rather stout overwintering roots. Stems may be solitary or more commonly clumped, and usually grow unbranched, reaching heights up to 40 cm tall. Stems are smooth or bear scattered short hairs. Leaves are 2—5 per stem, attached by means of a leaf sheath that is 13 cm long. Leaf blades are dull green, elongate, ending in a gradually tapered tip, flat or keeled, smooth (without hairs), and 1—3.5 dm long by 0.5—2.5 cm wide. Flowers occur in tight clusters located at the stem apex; bracts similar to the leaves …
Vascular Flora Of Powhatan County, Virginia, Michael Austin Terry, W. John Hayden
Vascular Flora Of Powhatan County, Virginia, Michael Austin Terry, W. John Hayden
Biology Faculty Publications
Powhatan County is a largely rural county of the Virginia piedmont currently experiencing exurban development pressure. Commercial pine forests occupy much of the land area; most natural vegetation occurs in various hardwood forests. Plant life is supported largely by soils derived from Proterozoic to Paleozoic metamorphic and igneous rocks, soils developed over Triassic basins, and riparian soils associated with the James and Appomattox Rivers. The annotated checklist is based on new collections gathered between September 2003 and August 2005, supplemented with records from regional herbaria and the Atlas of the Virginia Flora. Field work sampled at least 12 distinct community …
Atamasco Lily, Zephyranthes Atamasca, W. John Hayden
Atamasco Lily, Zephyranthes Atamasca, W. John Hayden
Biology Faculty Publications
Simple and pure, Atamasco lilies were among the first of many beautiful wildflowers to be noticed by the Jamestown colonists as they explored the tidewater region of southeastern Virginia. A perennial herb that grows from a subterranean bulb, the leaves are glossy green, linear, flat to somewhat concave, up to one half inch wide and approximately one foot in length. The species name, atamasca, is attributed to Tapehanek words meaning under grass, in reference to the location of the bulb under grass-like leaves. Overall the plant is rather grass-like. Flowers are erect to slightly inclined. As in many lilies, …
Zephyr Lilies: Simple Beauty Belies Complex Biology, W. John Hayden
Zephyr Lilies: Simple Beauty Belies Complex Biology, W. John Hayden
Biology Faculty Publications
It is often thus, the best in art appears effortless; the most compelling science, once understood, seems obvious. But talk at length with any artist or scientist and you will learn that what appears simple is actually the culmination of a great deal of work. Zephyr, or Jamestown, lilies are like that, too. These seemingly simple flowers are merely the elegant end product of some very complex underlying biology, the details of which are imperfectly understood.
2007 Wildflower Of The Year: Atamasco Lily, Zephyranthes Atamasca, W. John Hayden
2007 Wildflower Of The Year: Atamasco Lily, Zephyranthes Atamasca, W. John Hayden
Biology Faculty Publications
Atamasco lily is a perennial herb that grows from a subterranean bulb. The bulb is dark, with a short neck and papery tunic formed by remnants of old leaf bases. Leaves are glossy green, linear, flat to somewhat concave, up to one half inch wide, approximately one foot in length and, overall, rather grasslike. When not in flower the plants can be easily overlooked. Flowering stems are leafless scapes that are about as long as the leaves. In crosssection the scapes are hollow. Each scape terminates in a single flower. A few papery bracts subtend the flower stalk where it …
2006 Wildflower Of The Year: Spicebush, Lindera Benzoin, W. John Hayden
2006 Wildflower Of The Year: Spicebush, Lindera Benzoin, W. John Hayden
Biology Faculty Publications
Spicebush is a multistemmed deciduous shrub that grows to a height of one to three meters. Young stems are delicate and may be smooth or finely hairy. Leaves are alternate and simple, with an elliptic to obovate blade that tapers at both the base and apex and is bounded by a smooth margin. Examined closely, the margin will reveal a series of fine hairs that project directly out from the leaf edge. In size, leaves are neither remarkably large nor small; they range from one to six inches in length and up to about two and a half inches wide, …
Bloodroot Pollination: Bet-Hedging In Uncertain Times, W. John Hayden
Bloodroot Pollination: Bet-Hedging In Uncertain Times, W. John Hayden
Biology Faculty Publications
“Hurry up and wait.” The phrase that epitomizes life in the military or any other large, bureaucratic, organization, applies surprisingly well to bloodroot and similar ephemeral wildflowers. Each year these plants race to flower as early as possible to assure sufficient time for fruits to ripen and seeds to mature while sunshine is abundant at the forest floor, for all too soon the forest floor will be draped in shadows cast by the trees’ leafy canopy. Ephemerals do everything quickly: sprout, grow, flower, disperse seeds, and re-enter dormancy. But flowering in very early spring can be risky. Some days will …
Plant Composition Of Mixed-Grass Prairie Of Cedar Point Biological Research Station, Keith County, Nebraska, David A. Mckenzie
Plant Composition Of Mixed-Grass Prairie Of Cedar Point Biological Research Station, Keith County, Nebraska, David A. Mckenzie
Biology Faculty Publications
This study involved a vegetation analysis of 15 permanent plots established on the short-grass and mixed grass prairie slopes at the Cedar Point Biological Station in Keith County, Nebraska. Ninety-nine species were found in the plots, including members of 75 genera and 31 families. Twenty-one were graminoids, 71 were forbs or succulents, 6 were shrubs and one was a tree. Bouteloua gracilis (19 % cover) and Carex filifolia (15 % cover) were the dominant graminoids at the site, while Yucca glauca (1% cover) and Artemisia frigida (1% cover) were the most frequent forbs. Comparisons of species richness by slope categories …
2005 Virginia Wildflower Of The Year: Bloodroot, Sanguinaria Canadensis, W. John Hayden
2005 Virginia Wildflower Of The Year: Bloodroot, Sanguinaria Canadensis, W. John Hayden
Biology Faculty Publications
Bloodroot is an herbaceous perennial that grows from a persistent, branched underground stem or rhizome. Early each spring, while the forest canopy is still bare, each well-developed rhizome tip produces one leaf and one flower stalk. The leaf is kidney-shaped in its overall outline, but it is also divided into a pattern of rounded lobes and sinuses, rendering a complex overall shape. At flowering time, bloodroot leaves form a loose vertically-oriented collar around the flower stalk with the bluish-green lower leaf surface forming the outside of the collar; as the season progresses, the leaves open flat and expand to their …
Amanoa, W. John Hayden
Amanoa, W. John Hayden
Biology Faculty Publications
Monoecious or dioecious trees or shrubs, latex absent. Leaves alternate, distichous, evergreen, simple, coriaceous, glabrous; stipules intrapetiolar, paired, or confluent across the leaf axil; margins entire; venation pinnate. Inflorescence axillary and/or terminal, of densely bracteate clusters (reduced cymules), in the axils of ordinary foliage leaves, in nonleafy pseudoterminal aggregates that revert to vegetative growth, or (in neotropical species) in the axils of alternate, reduced, crescentiform stipular bracts of determinate deciduous spiciform axes borne in groups of 1-several per branch apex; axes straight or sinuous; floral bracts minute, deltate, with abaxially pubescent midribs. Staminate flowers sessile or pedicellate, regular; perianth biseriate; …
Seedling Development In Species Of Chamaesyce (Euphorbiaceae) With Erect Growth Habits, W. John Hayden, Olga Troyanskaya
Seedling Development In Species Of Chamaesyce (Euphorbiaceae) With Erect Growth Habits, W. John Hayden, Olga Troyanskaya
Biology Faculty Publications
Seedling development is described for Chamaesyce hirta, C. hypericifolia, and C. mesembrianthemifolia as discerned by light microscopy and scanning electron microscopy. Although these species ultimately develop erect to ascending growth habits, epicotyl development is limited to the production of a single pair ofleaves located immediately superjacent to and decussate with the cotyledons. The shoot system develops from one or more buds located in the axils of the cotyledons. In all respects, seedling ontogeny is very similar to that of previously studied prostrate species of Chamaesyce. Evidence from seedling ontogeny thus contradicts a hypothesis concerning homologies of plant …
Revision Of The Cerrado Hemicryptophytic Chamaesyce Of Boissier's "Pleiadeniae" (Euphorbiaceae), Mark P. Simmons, W. John Hayden
Revision Of The Cerrado Hemicryptophytic Chamaesyce Of Boissier's "Pleiadeniae" (Euphorbiaceae), Mark P. Simmons, W. John Hayden
Biology Faculty Publications
The species of Chamaesyce classified by Boissier as the "Pleiadeniae'" are revised in light of presently available collections. Six species are accepted and new combinations are proposed for C. nana, C. setosa, C. tamanduana, and C. viscoides. Although these herbaceous perennials of cerrado vegetation of Brazil, northern Argentina, and adjacent countries are distinctive ecologically and geographically, cladistic analysis does not support their recognition as a monophyletic group.
Taking Root, W. John Hayden
Taking Root, W. John Hayden
Biology Faculty Publications
The brief description of mangrove reproduction in John N. Cole's "Off Key, Out of Reach" [A Sense of Place, July-August] contains an error.
A Revision Of Discocarpus (Euphorbiaceae), Sheila M. Hayden, W. John Hayden
A Revision Of Discocarpus (Euphorbiaceae), Sheila M. Hayden, W. John Hayden
Biology Faculty Publications
As revised here, Discocarpus is interpreted to consist of three neotropical species: D. essequeboensis Klotzsch, D. gentryi S. M. Hayden, which is described and named herein as new to science, and D. spruceanus Müll. Arg. One previously accepted name, D. brasiliensis Klotzsch ex Müll. Arg., is reduced to synonymy of D. essequeboensis. Lecto-types are proposed for the two species previously described. One species is newly excluded from Discocarpus, as are three others, following previous literature. Foliar anatomy is described with a focus on epidermal sclereids, which are shown to occur on both epidermides. Evidence presented supports close relationships …
The Vascular Flora Of The Potomac River Watershed Of King George County, Virginia, Mark P. Simmons, Donna M.E. Ware, W. John Hayden
The Vascular Flora Of The Potomac River Watershed Of King George County, Virginia, Mark P. Simmons, Donna M.E. Ware, W. John Hayden
Biology Faculty Publications
The results of two floristic studies of King George County, Virginia, are combined into an annotated checklist. Field work was initiated in 1983-84 with a study of Caledon Natural Area, a 2,500-acre tract with 3.5 miles of frontage on the Potomac River. Collecting resumed in 1991 and 1992 to include other portions of the county drained by the Potomac River. The study area contains a wide variety of habitats including dry upland woods, mesic ravines, low elevation river flats, beaches, swamps, marshes, and creeks; creeks and marshes include both brackish and freshwater environments. The Potomac River watershed of King George …
Mistaken Identity?, W. John Hayden
Mistaken Identity?, W. John Hayden
Biology Faculty Publications
The December 1994 NEWS item "Red Menace" contains, I believe, an unfortunate misidentification of the algae allegedly responsible for the catastrophic mortality of sea birds from Pliocene deposits of the Florida Gulf Coast.
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; …
Nebraska Plant Distribution, David M. Sutherland, Robert B. Kaul
Nebraska Plant Distribution, David M. Sutherland, Robert B. Kaul
Biology Faculty Publications
Distribution notes based on recent collections and herbarium work are provided for 46 Nebraska plant taxa, including 43 flowering plants, two ferns, and one liverwort. The list includes several plants that are new to the State and provides range extensions within the State for many others. Several previously- published distribution records believed to be erroneous are also discussed.
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., …