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Full-Text Articles in Life Sciences
Nitrogen Fixation In Roots Of Ceanothus, W. John Hayden
Nitrogen Fixation In Roots Of Ceanothus, W. John Hayden
Biology Faculty Publications
Roots are usually out of sight and, therefore, out of mind. But as any good gardener will tell you, it is of utmost importance to understand those unique plant organs, even if their essential functions occur hidden from cursory observation. The red roots of the 2019 VNPS Wildflower of the Year, Ceanothus americanus, are particularly important because they host symbiotic bacteria that perform the essential function of nitrogen fixation. These prominent, knobby, distinctively pigmented roots are also the inspiration for the common name Redroot, applied to many species in the genus.
There's Much Left To Learn: Clethra's Chromosomes, W. John Hayden
There's Much Left To Learn: Clethra's Chromosomes, W. John Hayden
Biology Faculty Publications
Many would argue that chromosomes, genes, and DNA form the ineluctable essence of modern biology. Not only do these fundamental components of living cells provide moment-to-moment instructions by which cells carry out basic life processes, they also control inheritance of characteristics from one generation to the next. These essential functions of DNA stem from its repetitive structure. Hugely long DNA molecules are built from just four components, referenced by their singleletter abbreviations, A, C, G, and T. It is the specific sequence of these As, Cs, Gs, and Ts that constitutes the coded information of DNA. Moreover, molecular biologists have …
When It Comes To Clethra: Roots Matter, W. John Hayden
When It Comes To Clethra: Roots Matter, W. John Hayden
Biology Faculty Publications
Roots, too often, are out of sight and out of mind, but they are critical for vigorous, healthy plant growth. All plant enthusiasts—including gardeners, farmers, foresters, and naturalists—should think about and appreciate roots if they wish to acquire a holistic understanding of plant biology. This article introduces readers to the mycorrhizal roots of the 2015 VNPS Wildflower of the Year, Clethra alnifolia (Sweet Pepperbush), and explores the diversity of mycorrhizae in a closely related family, Ericaceae.
Upside-Down Anthers Of Clethra Stand Out, W. John Hayden
Upside-Down Anthers Of Clethra Stand Out, W. John Hayden
Biology Faculty Publications
For the most part, the flowers of the 2015 VNPS Wildflower of the Year, Clethra alnifolia (Sweet Pepperbush), are unremarkable. Five separate sepals, 5 sepa rate petals, 10 stamens in 2 whorls, and a 3-carpellate superior ovary—an organization that can only be considered prosaic among the dicots. One floral feature, however, stands out: the anthers in the open flowers are upside-down! (See Figure 1A.) Further, these upside-down anthers open by pores (Figures 1B, 1C) rather than longitudinal slits, as in most flowering plants. These pores initially form on what would normally be the lowermost extremity of the anther, the inversion …
Little Things Reveal The Big Picture, W. John Hayden
Little Things Reveal The Big Picture, W. John Hayden
Biology Faculty Publications
As enthusiasts who enjoy native plants in natural habitats, we tend to focus on gross morphology— aspects of plant form that can be readily observed with the naked eye or with a hand lens. And there is plenty to see at the gross level. The Flora of Virginia contains 1,269 pages of keys and descriptions devoted to gross morphology of the commonwealth’s botanical treasures. Morphological diversity, however, does not stop at the magnifi cation limit of a hand lens. Light and electron microscopes open up whole new worlds of intricate structure for appreciation and study. And tiny structural details can …
Native Orchids In Winter?, W. John Hayden
Native Orchids In Winter?, W. John Hayden
Biology Faculty Publications
A very special place in Southwest Virginia will soon expand its borders, thanks in part to the annual fundraising appeal by the Virginia Native Plant Society. The Cedars Natural Area Preserve supports ex ceptional natural communities including rocky, dry limestone glades and woodlands located across nearly 20 square miles in Lee County near the Powell River. The karst landscape, where thin soils develop over easily dissolved limestone bedrock, creates terrain that tends to be rolling, rocky, rugged, and full of sinkholes, caves, and sinking streams. The preserve is a haven for rare plants that have adapted to the mostly thin, …
2015 Virginia Wildflower Of The Year: Sweet Pepperbush, Clethra Alnifolia, W. John Hayden
2015 Virginia Wildflower Of The Year: Sweet Pepperbush, Clethra Alnifolia, W. John Hayden
Biology Faculty Publications
Clethra alnifolia is a rhizomatous shrub with aerial stems from 1 to 3 m tall. Leaves are simple, alternate, and bear stellate hairs; petioles are short, 5–10 mm long; leaf blades are obovate to oblong, 5–10 cm long, with relatively blunt apices, cuneate (wedgelike) bases, and margins that are entire toward the base but finely serrate above the middle; venation is pinnate with secondary veins that extend to leaf margins. Stipules are lacking. Flowers are borne on erect terminal racemes that may be solitary or accompanied by additional racemes terminating few-leaved branches arising from upper nodes. Raceme axes and pedicels …
Two Honeysuckles: A Tale Of Dr. Jekyll And Mr. Hyde, W. John Hayden
Two Honeysuckles: A Tale Of Dr. Jekyll And Mr. Hyde, W. John Hayden
Biology Faculty Publications
There are about 180 species of Lonicera (honeysuckles) widely distributed in the north temperate zone. These are mostly shrubby plants, but in Virginia, we have two species that are woody vines (lianas). These two lianous honeysuckles should be familiar to all Virginia Native Plant Society members. One is this year’s VNPS Wildflower of the Year, Lonicera sempervirens (coral honeysuckle), and the other is Lonicera japonica (Japanese honeysuckle), widely and deservedly reviled as one of our most aggressive invasive exotic species. Together, these two plants make an odd pair, a sort of botanical Dr. Jekyll and Mr. Hyde. What is it, …
Redbud Cauliflory: The Inside Story, W. John Hayden
Redbud Cauliflory: The Inside Story, W. John Hayden
Biology Faculty Publications
One of the most distinctive features of redbuds, Cercis canadensis, the 2013 VNPS Wildflower of the Year, is its production of flowers on mature trunks and major branches, a habit termed cauliflory. Redbud flowers also form on young, one-year old twigs; as explained below, twig- and trunk-borne flowers are parts of a single developmental continuum; twigs bearing flowers eventually becoming trunks and large branches that continue to bear flowers.
Partridge Berry: Simple Beauty Belies Complexity, W. John Hayden
Partridge Berry: Simple Beauty Belies Complexity, W. John Hayden
Biology Faculty Publications
Superficially, plants seem so simple. Rooted in place, they do not move around. And while plant growth is a dynamic process, without time-lapse photography, growth events are so imperceptibly slow that, to us impatient humans, plants seem both immobile and static. Nevertheless, there is a lot going on inside the plant body, and this is especially true for the events of reproduction that play out inside flowers and fruits. As one of my students recently commented, “I used to think it was just a matter of pollen plus stigma and, presto-change-o, seeds happen.” That student, I hope, learned otherwise, as …
2012 Wildflower Of The Year: Partridge Berry, Mitchella Repens, W. John Hayden
2012 Wildflower Of The Year: Partridge Berry, Mitchella Repens, W. John Hayden
Biology Faculty Publications
Although partridge berry is a small and creeping herb, its jewel-like beauty rewards attentive naturalists year-round.
Oak Galls: A Strange Biology Indeed!, W. John Hayden
Oak Galls: A Strange Biology Indeed!, W. John Hayden
Biology Faculty Publications
Anyone who takes the time to look closely at several branches of oak will soon find one or another peculiar anomaly among the leaves and twigs. One can easily find structures resembling Ping-Pong balls, hard knots, fluffy tufts, horns—either single or clustered, or irregular thickenings, to mention just a few possibilities. These abnormal growths are galls, structures caused by the presence of small insect larvae living inside the tissue of the plant. Galls can be found on a wide variety of plants. They are common, for example, on the stems of goldenrods, and the leaves of maples, but oaks are …
Hybrid Oaks: Full Of Vexation And Wonder, W. John Hayden
Hybrid Oaks: Full Of Vexation And Wonder, W. John Hayden
Biology Faculty Publications
Distinguishing different species of oak in the forests of eastern North America can be challenging. For one thing, there are simply a lot of different species to sort out. A recent reference (Stein et al. 2003), describes 50 species in the genus Quercusoccurring naturally east of the 100th meridian, and 90 species are distinguished for all of North America north of Mexico (Nixon 1997). With so many species to parse, confident identification requires careful study of leaves, stem and leaf hairiness, and fully mature acorns with their caps. But care is not always enough, because in addition to the …
2011 Wildflower Of The Year: White Oak, Quercus Alba, W. John Hayden
2011 Wildflower Of The Year: White Oak, Quercus Alba, W. John Hayden
Biology Faculty Publications
Emblematic of strength and longevity, white oaks grace the deciduous forests of eastern North America.
Don't Judge A Book By Its Cover: The Curious Case Of Wild Ginger Pollination, W. John Hayden
Don't Judge A Book By Its Cover: The Curious Case Of Wild Ginger Pollination, W. John Hayden
Biology Faculty Publications
What pollinates wild ginger? This seems like an easy question. The inconspicuous little flowers are held close to the forest floor, often completely hidden by a dense canopy of ginger leaves above. Flower color is rather drab, dominated by brown and maroon hues. Wind pollination seems completely unlikely and flowers pollinated by bees, butterflies, moths, or hummingbirds are always much more showy and accessible to these flying creatures. Flies, however, given their natural inclination to seek carrion as a food source for their babies (i.e. maggots), are often attracted to brown and maroon flowers. And because their actual quarry, animal …
2010 Wildflower Of The Year: Wild Ginger, Asarum Canadense, W. John Hayden
2010 Wildflower Of The Year: Wild Ginger, Asarum Canadense, W. John Hayden
Biology Faculty Publications
Wild ginger is a low herbaceous plant. The stem consists of a branched creeping rhizome at or just below the soil surface. Soft-hairy leaves arise in pairs annually from rhizome branches. Petioles can be up to 20 cm long, elevating the 7—25 mm wide kidney-shaped leaf blades above the forest floor. Small flowers appear in the spring shortly after the leaves have expanded. Typically, one must push the leaves aside in order to glimpse the jug-like flowers. A single flower stalk appears between the paired leaf bases, but it is short and barely lifts the flower above the soil surface. …
2009 Wildflower Of The Year: Skunk Cabbage, Symplocarpus Foetidus, W. John Hayden
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 …
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 …
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, …
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 …