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Biology Faculty Publications

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Articles 61 - 90 of 112

Full-Text Articles in Plant Biology

Hunker Down And Hold On: Contractile Roots Give Skunk Cabbage Another Special Trait, W. John Hayden Apr 2009

Hunker Down And Hold On: Contractile Roots Give Skunk Cabbage Another Special Trait, W. John Hayden

Biology Faculty Publications

I can remember the first time I ever heard of contractile roots. It was in graduate school at the University of Maryland and a friend of mine was busy preparing a lecture on roots. He said to me something like “Did you ever notice, while pulling up dandelions, that the darn weed seems to be pulling back? As it turns out, it is!” Strange but true, dandelions, along with a diverse assemblage of other species, have contractile roots that serve to pull the plant downward. In this capacity, contractile roots go well beyond the routine function of providing anchorage for …

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2009 Wildflower Of The Year: Skunk Cabbage, Symplocarpus Foetidus, W. John Hayden Jan 2009

2009 Wildflower Of The Year: Skunk Cabbage, Symplocarpus Foetidus, W. John Hayden

Biology Faculty Publications

Skunk cabbage is a coarse herbaceous plant. The stem consists of a stout rhizome oriented vertically in the soil. Leaves and flowers arise from the tip of the rhizome which is often not visible, resulting in the appearance of leaves and flowers arising directly from the swampy mires where these plants grow. Flowers appear during the winter, long before the leaves. The flowers are minute, clustered into a ball-like group (spadix) almost entirely enclosed by a fleshy, hood-like, spathe. The spathe ranges from 8 to 15 cm in height, is more or less pear-shaped, widest near the bottom, and tapers …

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Skunk Cabbage Flowers: The Heat Is On, W. John Hayden Jan 2009

Skunk Cabbage Flowers: The Heat Is On, W. John Hayden

Biology Faculty Publications

It is a remarkable sight, as striking as it is unexpected: January skunk cabbages emerging from the frozen mires they call home, melting their way through snow and ice. It seems so improbable because in everyday experience plants exist at equilibrium with ambient temperatures. Leave an apple on the front seat of your car in summer, it gets hot; examine your tomato plants on that first frosty morning in autumn, and they are permeated with ice crystals. People, mammals and birds are inherently warm, and pretty much nothing else is. Except, of course, for the exceptions, of which skunk cabbage …

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Spiderworts: Not Just Another Pretty Face For Science, W. John Hayden Jul 2008

Spiderworts: Not Just Another Pretty Face For Science, W. John Hayden

Biology Faculty Publications

Species of Tradescantia, or spiderworts, are handsome plants. Several wild species, including the VNPS wildflower of the Year for 2008 (T. virginiana), can be found in eastern North America and additional species grace gardens, and hothouse conservatories. Spiderworts are not, however, just a bunch of pretty faces. Spiderworts have a long history of service to science, both in terms of teaching and pure research.

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Spiderwort Is Vnps Wildflower Of The Year, W. John Hayden Jan 2008

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.

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2008 Wildflower Of The Year: Virginia Spiderwort, Tradescantia Virginiana, W. John Hayden Jan 2008

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 …

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Atamasco Lily, Zephyranthes Atamasca, W. John Hayden May 2007

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, …

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Zephyr Lilies: Simple Beauty Belies Complex Biology, W. John Hayden Apr 2007

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.

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Are Hawkmoths The Mysterious Pollinators Of The Jamestown Lily?, W. John Hayden Feb 2007

Are Hawkmoths The Mysterious Pollinators Of The Jamestown Lily?, W. John Hayden

Biology Faculty Publications

“Hawkmoth flowers are easy to predict but difficult to document,” noted botanist Verne Grant in his comprehensive review of hawkmoth pollination systems in North America (Botanical Gazette 144: 439-449. 1983). Grant included Jamestown (atamasco) lilies (among other zephyr lily species) as examples of plants that are probably hawkmoth- pollinated, but for which the actual pollination mechanism remains undocumented.

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2007 Wildflower Of The Year: Atamasco Lily, Zephyranthes Atamasca, W. John Hayden Jan 2007

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 …

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2006 Wildflower Of The Year: Spicebush, Lindera Benzoin, W. John Hayden Jan 2006

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, …

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Bloodroot Pollination: Bet-Hedging In Uncertain Times, W. John Hayden Feb 2005

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 …

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2005 Virginia Wildflower Of The Year: Bloodroot, Sanguinaria Canadensis, W. John Hayden Jan 2005

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 …

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Seed Mass And Morphology In Outcrossing And Selfing Species Of Clarkia (Onagraceae): An Sem Study, Jennifer L. Knies, Veronique A. Delesalle, A. R. Cavaliere Jan 2004

Seed Mass And Morphology In Outcrossing And Selfing Species Of Clarkia (Onagraceae): An Sem Study, Jennifer L. Knies, Veronique A. Delesalle, A. R. Cavaliere

Biology Faculty Publications

Seeds from three pairs of outcrossing-selfing sister taxa from the genus Clarkia (farewell-to-spring, Onagraceae)—Clarkia unguiculata, Clarkia exilis, Clarkia xantiana ssp. xantiana and ssp. parviflora, and Clarkia concinna ssp. concinna and ssp. automixa—were studied to assess the effects of contrasting mating systems on seed mass and seed morphology. For each outcrossing-selfing comparison, the seed mass of the selfing taxon was less than that of the outcrossing taxon. Seed mass typically differed significantly among populations within a taxon. Scanning electron microscopy showed that the seeds from all these taxa share several characteristics: a bullet to shield shape, a reticulate exotesta pattern, presence …

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Amanoa, W. John Hayden Jan 1999

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; …

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Seedling Development In Species Of Chamaesyce (Euphorbiaceae) With Erect Growth Habits, W. John Hayden, Olga Troyanskaya Jan 1998

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 …

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Revision Of The Cerrado Hemicryptophytic Chamaesyce Of Boissier's "Pleiadeniae" (Euphorbiaceae), Mark P. Simmons, W. John Hayden Apr 1997

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.

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Taking Root, W. John Hayden Sep 1996

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.

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A Revision Of Discocarpus (Euphorbiaceae), Sheila M. Hayden, W. John Hayden Jan 1996

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 …

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The Vascular Flora Of The Potomac River Watershed Of King George County, Virginia, Mark P. Simmons, Donna M.E. Ware, W. John Hayden Sep 1995

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 …

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Mistaken Identity?, W. John Hayden Apr 1995

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.

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Systematic Anatomy Of Euphorbiaceae Subfamily Oldfieldioideae I. Overview, W. John Hayden Jan 1994

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 …

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Stem Development, Medullary Bundles, And Wood Anatomy Of Croton Glandulosus Var. Septentrionalis (Euphorbiaceae), Sheila M. Hayden, W. John Hayden Jan 1994

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 …

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Woody Vegetation Of A Disjunct Bur Oak (Quercus Macrocarpa) Forest In East-Central Nebraska, Debra Ann Beightol, Thomas B. Bragg Jan 1993

Woody Vegetation Of A Disjunct Bur Oak (Quercus Macrocarpa) Forest In East-Central Nebraska, Debra Ann Beightol, Thomas B. Bragg

Biology Faculty Publications

Woody plant composition was assessed for three tree-size classes in two ravines of Oak Glen Wildlife Management Area, a disjunct oak forest in Seward County, Nebraska, using Importance Values (IV) obtained by the Point-Quarter method. Bur oak (Quercus macrocarpa Michx.) dominated the large-size class (>30 cm dbh) (IV = 258) but elms (Ulmus americana L. and U. rubra Muhl.) (IV = 130) dominated the forest in one ravine in the medium-size class (10-30cm dbh) and elm and hackberry (Celtis occidentalis L.) (IV = 114 and 27 respectively) dominated the small-size class (

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Review Of American Wildflower Florilegium By Jean Andrews, David M. Sutherland Jan 1993

Review Of American Wildflower Florilegium By Jean Andrews, David M. Sutherland

Biology Faculty Publications

This book is a collection of 50 watercolor paintings of American wildflowers ("florilegium" means, literally, "a gathering of flowers"). Accompanying each full-page painting is a summary of general information about the plant, including notes about its botanical classification, the etymology of its name, life history, distribution, description, flowering period, pollination, and propagation.

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Floristic Diversity In Ten Tallgrass Prairie Remnants Of Eastern Nebraska, Judith F. Boettcher, Thomas B. Bragg, David M. Sutherland Jan 1993

Floristic Diversity In Ten Tallgrass Prairie Remnants Of Eastern Nebraska, Judith F. Boettcher, Thomas B. Bragg, David M. Sutherland

Biology Faculty Publications

Ten eastern Nebraska tallgrass prairie remnants, varying in size from one to 18 ha, were studied or visited during the growing seasons from 1979 to 1993. A total of217 prairie plant species were recorded. Big bluestem (Andropogon gerardii), little bluestem (Andropogon scoparius), smooth brome (Bromus inermis subsp. inermis), New Jersey tea (Ceanothus herbaceus var. pubescens), false sunflower (Heliopsis helianthoides var. scabra), Kentucky bluegrass (Poa pratensis), and porcupine-grass (Stipa spartea) were prevalent in all the prairies although the specific floristic composition has been reported to vary depending on past management, topography, season of evaluation, and prairie size. Of the total species …

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Wood Anatomy Of Amanoa (Euphorbiaceae), W. John Hayden, Mark P. Simmons, Linda J. Swanson Jan 1993

Wood Anatomy Of Amanoa (Euphorbiaceae), W. John Hayden, Mark P. Simmons, Linda J. Swanson

Biology Faculty Publications

Wood anatomy of 29 specimens of seven species of Amanoa from tropical Africa, South America, and the Caribbean is described. The wood is diffuse-porous with most vessels in short radical multiples. Vessel elements are notably long, have simple perforation plates and small, alternative intervessel pits; tyloses are present in heartwood. Libriform wood fibres bear thick walls. Axial parenchyma distribution is diffuse and diffuse-in-aggregates. Chambered crystalliferous axial parenchyma is common. Rays are heterocellular, narrow, and very tall. The species examined, all from moist lowland forests, have similar wood structure. Wood of Amanoa resembles that of other primitive Euphorbiaceae.

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A Survey Of Mucilaginous Testa In Chamaesyce, Martha S. Jordan, W. John Hayden Apr 1992

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 …

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Review Of The Wild Oat Inflorescence And Seed: Anatomy, Development And Morphology, M. V. S. Raju, David M. Sutherland Aug 1991

Review Of The Wild Oat Inflorescence And Seed: Anatomy, Development And Morphology, M. V. S. Raju, David M. Sutherland

Biology Faculty Publications

This slim volume describes a detailed study of the reproductive parts of Avena fatua, the wild oat plant-a common weed in the northern plains and the probable ancestor of the cultivated oat. The book integrates the author's own work with information from available literature and includes lengthy technical descriptions of the structure and the growth of the inflorescence, the floret, the ovule, the pollen grain, the embryo, the seed, and the young seedling. Throughout the work, the author relates the wild oat's structure and development to other grasses, other monocotyledons, and other seed plants, offering evolutionary interpretations of many of …

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A Taxonomic Study Of Variation In Leptochloa Fascicularis (Lam.) Gray In The Central Great Plains, Todd A. Templeton Jan 1991

A Taxonomic Study Of Variation In Leptochloa Fascicularis (Lam.) Gray In The Central Great Plains, Todd A. Templeton

Biology Faculty Publications

The morphology of Leptochloa fascicularis (Lam.) Gray (Poaceae) was studied in 25 locations in eastern and central Nebraska to determine if this grass was separable into two distinct taxa as suggested in several recent sources. Field collections were supplemented with herbarium specimens from other parts of the Central Great Plains. Glume and lemma lengths, the characters used in published keys, provided no separations useful in dividing the material into two species or varieties. However, individual local populations exhibited significant differences from each other in these characters. Such local differences appear to be reasonable given the high degree of inbreeding that …

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