Digital Commons Network^™

Humming Birds: Pollination Facts And Fancy, W. John Hayden

Biology Faculty Publications

Coral honeysuckle (Lonicera sempervirens), the 2014 VNPS Wildflower of the Year, is a classic example of a hummingbird-pollinated flower: bright red petals, often with contrasting yellow tones in the corolla throat, provide visual attraction, drawing hummingbirds to the flowers, where they are rewarded with a rich supply of nectar. Whereas hummingbirds have good color vision, they have a poor sense of smell. So it is not surprising that coral honeysuckle flowers are nearly scentless, at least to the human nose; even modern analytical instruments detect only traces of volatile molecules emanating from them. And open coral honeysuckle flowers, …

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, …

2014 Virginia Wildflower Of The Year: Coral Honeysuckle, Lonicera Sempervirens, W. John Hayden

Biology Faculty Publications

The flashy red flowers of coral honeysuckle beckon hummingbirds to their sweet nectar. Coral honeysuckle is a twining woody vine, usually climbing on other vegetation but sometimes trailing along the ground; older stems have papery-brown exfoliating bark.

Incorporating Risk Of Reinvasion To Prioritize Sites For Invasive Species Management, Todd R. Lookingbill, Emily S. Minor, Nadia Bukach, Joseph R. Ferrari, Lisa A. Wainger

Geography and the Environment Faculty Publications

The relationship between landscape pattern and the distribution and spread of exotic species is an important determinant of where and when management actions are best applied. We have developed an interdisciplinary approach for prioritizing treatment of harmful, nonnative, invasive plants in National Park landscapes of the Mid-Atlantic USA. The approach relies upon a detailed model of reinvasion risk that combines information on: (1) global factors representing park-level infestation from seed and sprout, (2) landscape factors including disturbance-based spread vectors and neighborhood seed density, and (3) local factors determining establishment probability based on habitat suitability. Global seed rain estimates are derived …

Commelina Benghalensis New To Virginia, W. John Hayden

Biology Faculty Publications

This is the first report of Commelina benghalensis (Benghal dayflower, tropical spiderwort) in Virginia. Three mature plants with intertwined stems bearing numerous chasmogamous and cleistogamous flowers were discovered as weeds in a landscape planting of hybrid Hemerocallis, hybrid Iris, and a dwarf cultivar of Nandina domestica; nine nonreproductive seedlings were found about one meter distant in the same flower bed.

Redbud Seedpods Hold Surprises, W. John Hayden

Biology Faculty Publications

As fall advances across the Old Dominion, canopies of redbud, the 2013 VNPS Wildflower of the Year, transform themselves from green to gold, revealing seed pods also changing color from pale green to dark chocolaty brown. These seedpods, which may be retained on the tree into winter, are typical legume fruits, the product of the flower’s simple pistil, each containing several seeds. Unlike most legumes, however, redbud seed pods seem disinclined to open and release individual seeds for dispersal. Redbud fruits tend to disperse intact. Once on the ground, the inevitable action of weather and microbes gradually degrades the pod, …

Redbuds Similar Around The World, W. John Hayden

Biology Faculty Publications

Like music, one of the hallmarks of biodiversity is theme and variation. Redbuds—species of the genus Cercis— from around the world illustrate this analogy well. Because all redbud species conform to a certain morphological theme, anyone familiar with one particular species of redbud should be able to recognize without hesitation any other redbud species as a member of the genus Cercis. In brief, the redbud theme consists of broad, basally-lobed, leaves with pulvinar petiole thickenings, and pea-like red-purple (rarely white) flowers that may arise on small twigs or main trunks. In fact, these plants are so distinctive, it would …

Redbuds And Legumes Subfamilies, W. John Hayden

Biology Faculty Publications

Although legumes constitute one of the largest families of flowering plants in the world, and despite 25 years of celebrating Virginia’s wildflowers, redbud (Cercis canadensis) is the first legume to be recognized as a VNPS Wildflower of the Year. This article addresses the relationships of Cercis with the rest of the legumes (family Fabaceae, or Leguminosae in older literature).

2013 Virginia Wildflower Of The Year: Redbud, Cercis Canadensis, W. John Hayden

Biology Faculty Publications

Redbuds are small trees or shrubs that may attain heights of 10 m or so. Leaves are alternate and two-ranked, simple, entire, deciduous, broadly cordate, with an acute apex, 611 cm long, 712 cm wide, and palmately veined. Petioles have two swollen pulvini, one at its connection with the stem, the other at its junction with the leaf blade.

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.

Threshold Responses Of Forest Birds To Landscape Changes Around Exurban Development, Todd R. Lookingbill, Marcela Suarez-Rubio, Scott Wilson, Peter Leimgruber

Geography and the Environment Faculty Publications

Low-density residential development (i.e., exurban development) is often embedded within a matrix of protected areas and natural amenities, raising concern about its ecological consequences. Forest-dependent species are particularly susceptible to human settlement even at low housing densities typical of exurban areas. However, few studies have examined the response of forest birds to this increasingly common form of land conversion. The aim of this study was to assess whether, how, and at what scale forest birds respond to changes in habitat due to exurban growth. We evaluated changes in habitat composition (amount) and configuration (arrangement) for forest and forest-edge species around …

Closely Paired Flowers Produce Single Fruit, W. John Hayden

Biology Faculty Publications

Perhaps one of the most striking features of partridge berry (Mitchella repens), the 2012 VNPS Wildflower of the Year, is its closely paired flowers that yield a single berry fruit (figure 1). That these fruits are double structures, formed by pairs of flowers, is revealed in the presence of two discrete rings of five sepals each on the fruit apex, or in some cases, by a single ring of 10 sepals. Viewed in isolation, without context, the nature of these double fruits may seem perplexing, but as in so many things, a comparative perspective helps to make sense …

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

Biology Faculty Publications

Although partridge berry is a small and creeping herb, its jewel-like beauty rewards attentive naturalists year-round.

Light Management Important Factor For Partridge Berry, W. John Hayden

Biology Faculty Publications

Factors essential for plant life include adequate levels of light, moisture, mineral nutrients, and temperature; though the list is small, each is crucial for survival. This article is a contemplation of how one of these critical factors, light, impacts the biology of our 2012 Wildflower of the Year, Mitchella repens, partridge berry. Aside from issues of reproductive biology, ecological literature on partridge berry is meager. Consequently most of what follows is derived from general works on woodland ecology, perusal of which provides sufficient insight about the biology of Mitchella to inspire ideas worthy of further study.

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 …

White Oak Part Of Global Oak Presence, W. John Hayden

Biology Faculty Publications

As we act locally celebrating white oak, Quercus alba, as the 2011 VNPS Wildflower of the Year, it is perhaps appropriate to think globally for a few moments and consider the breadth of diversity encompassed by the oaks. Quercus is a big genus, easily the largest in its family, the Fagaceae. Approximately 400 species of oak are known, and they are widely distributed in the northern hemisphere. We tend to think of oaks as temperate zone trees, but in the New World, their range extends south through the mountains of Central America to Colombia and in the Old World, …

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

Biology Faculty Publications

Emblematic of strength and longevity, white oaks grace the deciduous forests of eastern North America.

One Lump Or Two: How Many Wild Gingers Inhabit North America?, W. John Hayden

Biology Faculty Publications

Depending on which source one consults, the answer is either one (Asarum), or two (Asarum + Hexastylis). It is a classic lump-or-split situation. To mention just a few sources, Fernald (1950) and Gleason & Cronquist (1991) lump all the wild gingers into a single genus, whereas Radford et al. (1968), the Digital Atlas of the Virginia Flora (Virginia Botanical Associates 2010), and the Flora of North America (Whitmore & Gaddy 1997; Whitmore et al. 1997) split Asarum and Hexastylis apart. Deference to authority is a poor way to assess any scientific question, and for these wild …

Gender And Species Use In Amazonian Home Gardens: The Social And Economic Context Of Biodiversity Conservation, Leigh Ann West, David S. Salisbury, Ana I. Ríos-Sanchez, Jorge Vela Alvarado

Geography and the Environment Poster Presentations

Home gardens, “the peridomestic area belonging to the household where members plant and/or tend useful plants” (Perrault-Archambault and Coomes 2008), are found throughout the world. However, their use and importance vary from region to region. In the Peruvian Amazon, owners use home gardens for a domestic supply of foods, craft materials, medicines, condiments, and shade (Miller and Nair 2006). With this wide range in function, reflected in species content, home gardens are very biodiverse.

Home garden biodiversity may be increasingly important in a rapidly changing Amazonia (Betts et al. 2008). Thus, the sociocultural and economic factors contributing to home garden …

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

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. …

Combining A Dispersal Model With Network Theory To Assess Habitat Connectivity, Todd R. Lookingbill, Robert H. Gardner, Joseph R. Ferrari, Cherry E. Keller

Geography and the Environment Faculty Publications

Assessing the potential for threatened species to persist and spread within fragmented landscapes requires the identification of core areas that can sustain resident populations and dispersal corridors that can link these core areas with isolated patches of remnant habitat. We developed a set of GIS tools, simulation methods, and network analysis procedures to assess potential landscape connectivity for the Delmarva fox squirrel (DFS; Sciurus niger cinereus), an endangered species inhabiting forested areas on the Delmarva Peninsula, USA. Information on the DFS’s life history and dispersal characteristics, together with data on the composition and configuration of land cover on the peninsula, …

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 …

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 …

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 …

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.

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 …

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.