Thermal disorder in ionic crystals

Imperial Users onl

Stem Development, Medullary Bundles, and Wood Anatomy of \u3ci\u3eCroton Glandulosus Var. Septentrionalis\u3c/i\u3e (Euphorbiaceae)

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 orientation, i.e., phloem innermost (towards centre of pith) and xylem outermost (near protoxylem). Cells of the medullary bundles include sieve tube elements, vessel elements, and fibres. Normal (external) secondary phloem is weakly developed. Normal secondary xylem contains short vessel elements with simple perforation plates and alternate intervascular pits, libriform fibres, narrow heterocellular rays, and lacks axial parenchyma

Wood Anatomy and Relationships of \u3ci\u3eBetula uber\u3c/i\u3e

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

A Revision of \u3ci\u3eDiscocarpus\u3c/i\u3e (Euphorbiaceae)

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 with Lachnostylis Turcz. and Amanoa Aubl.; little was found to support previous hypotheses concerning a relationship with Chonocentrum Pierre ex Pax & K. Hoffm

Oh No! Something Is Eating My Coral Honeysuckle!

Let’s imagine a situation that could happen in your own backyard. Suppose you have a healthy specimen of 2014’s Virginia Native Plant Society Wildflower of the Year, coral honeysuckle (Lonicera sempervirens). Suppose further that this plant rewards you every spring with a flush of flashy red flowers that you treasure all the more because they consistently bring hummingbirds to your yard. Now imagine that one fine morning you notice some little green caterpillars voraciously eating the leaves of your beloved coral honeysuckle. What do you do

Closely Paired Flowers Produce Single Fruit

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 of conundrums such as this one

Redbud Seedpods Hold Surprises

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, whereupon the process of seed germination can proceed

Taking Root

The brief description of mangrove reproduction in John N. Cole\u27s Off Key, Out of Reach [A Sense of Place, July-August] contains an error

Celebrating NJ Tea’s Unspecialized Pollination

Specialized pollination systems are the source of some of the most compelling stories in natural history. There is something appealing to the human psyche about what seems to be a reciprocal agreement between a given plant and its dedicated pollinator: the plant attracts a pollinator and provides ample nectar and/or pollen as a reward for the pollinator’s service in moving pollen from anthers to stigmas while foraging for food. Of course, these organisms have neither signed agreements nor memos of understanding. Instead, it has merely proven to the benefit of the plant, over time, to form certain floral structures, and to produce excess pollen and/or nectar. Likewise, certain behaviors by the pollinators have proven, in the long run, beneficial to the survival of the pollinator. To put it in human terms, each is acting in its own self-interest, but together they are like pieces of a puzzle that fit together perfectly. Thus, for example, Cardinal Flower (Lobelia cardinalis, the 1991 VNPS WOY) is bright red, a color highly attractive to hummingbirds, the flower is zygomorphic (bilaterally symmetric), which channelizes the hummingbird’s approach to a direct, head-on orientation, from which the anthers are positioned in just the right spot to dust pollen on the face of the hummingbird as it probes deeply into the flower for a sip of nectar; a second visit to another flower will smear some of that pollen directly onto a perfectly positioned stigma. Mission accomplished