Saturday, October 10, 2009

American Black Nightshade

Solanum american; American Black Nightshade
The tiny white flowers are followed by conspicuous, glossy black berries that are eaten by a wide variety of birds and mammals.
Two species of black nightshade are native to Florida, Solanum americanum, the American black nightshade (also known as the common or glossy black nightshade), and Solanum chenopodioides, the goosefoot black nightshade. The former has shiny black fruits that are held erect and are so glossy as to appear coated with varnish, whereas the latter has nodding, dull black fruits. In general, black nightshades are ignored by gardeners and are regarded as weedy annuals of little horticultural merit.
Being common weeds, I did not pay any more attention to the black nightshades occurring in Florida than I did to black nightshades growing in Chicago alleys or in waste ground in Puerto Rico. However, my negative views changed when, on an impulse, I rescued a seedling of Solanum americanum growing in a lawn in downtown West Palm Beach. The seedling was established in a pot of sandy soil, and, when it was well-rooted, planted in a sunny, moist spot in the garden. American black nightshade occurs in nearly every county in Florida in a wide variety of both upland and wetland sites. Therefore, I had no doubts that it would be easy to grow and easy to propagate from cuttings and seeds, and that indeed turned out to be the case.
The seedling soon grew into a bushy plant nearly 3 feet high and almost as wide, bore innumerable little flowers, and became laden with an equal number of showy, glossy black fruits. Growing in close proximity in the garden, I was able to carefully observe this plant and learned that this much maligned "weed" had many virtues.
Solanum americanum is a fast-growing pioneer plant that helps to stabilize recently disturbed soil—this is an important ecological role. In the garden, it plays the useful role of attracting a wide variety of wildlife. Most Solanum species, including American black nightshade, have flowers adapted for pollination by bees. Each anther opens by a tiny pore at its tip and the pollen is inaccessible to most insects. Bees, however, are able to shake the pollen out of the anthers by grasping it with their legs and buzzing their wings. The resulting vibrations cause the pollen to spill out of the anthers in the same manner that shaking a salt shaker causes salt to spill out. Once the fruits are set and begin to ripen, the plant becomes attractive to larger animals and 31 birds and a dozen mammals have been recorded as eating the berries of American black nightshade.
Like many other plants, American black nightshade has its flaws and three stand out in particular. Being an annual or short-lived perennial, plants are not permanent in the garden and must be periodically replaced. Secondly, as with all plants, it is sometimes afflicted by pests, the most frequent being aphids and leaf miners, but occasionally tobacco or tomato hornworms may make a meal of foliage. Aphids and leaf miners are tolerated by me since I feel that they contribute to the diversity of wildlife in my yard and I leave hornworms alone since they grow into hawkmoths, which are important pollinators of native plants whose flowers open at dusk. Lastly, large plants with masses of black, glossy berries may seem out of place among gayly colored wildflowers and look as if they would be more at home in the herb or vegetable garden.
Since black nightshades can become serious agricultural weeds, I was worried that the seedling I rescued would overrun my garden. Fortunately, black nightshades are specialized for colonizing open, disturbed ground and, in my experience, the seeds will not germinate if the ground is covered in any way, such as by mulch, fallen leaves, or other plants. Thus, in spite of both the original and subsequent plants producing huge crops of berries, less than two dozen seedlings have spontaneously appeared in my garden in four years.
Some gardeners may hesitate to grow American black nightshade because it is frequently encountered on lists of poisonous plants. However, and rather paradoxically, it is just as frequently encountered on lists of edible plants! Strong evidence of its edibility has come from feeding experiments with cattle that ultimately were unable to demonstrate any toxicity (Rogers & Ogg 1981). Additionally, there are numerous instances of the leaves and ripe berries being used as food both by aboriginal and modern cultures throughout its range. Recently, Solanum americanum has received attention as a vegetable worthy of domestication to supplement the nutrition of poor, rural, Central American communities. The plant is already a component of the everyday diet of such communities and scientific investigations have shown that American black nightshade grows rapidly, adapts well to a wide range of altitudes and soils, and has more protein, calories, fiber, calcium, iron, B vitamins, and vitamin C than spinach (De Macvean & Pöll 2002). Because of the conflicting reports of its toxicity, there is some speculation that perhaps both toxic and nontoxic races exist. This theory is supported by observations that some plants have bitter leaves and unpleasant tasting berries while others have bland leaves and mildly sweet berries.
Conservation Note: Florida's only other species of black nightshade, Solanum chenopodioides, while common in most parts of Florida, is listed as critically imperiled in southern Florida by the Institute for Regional Conservation. As a result, care should be taken not to endanger south Florida populations of Solanum chenopodioides by collecting plants or removing cuttings or seeds.

De Macvean, A.L. and Pöll, E. 2002. Ethnobotany (Chapter 8). In: Vozzo, J.A. (ed.) Tropical tree seed manual. U.S. Department of Agriculture, Forest Service. Agriculture Handbook No. 721.

Rogers, B.S. and Ogg, A.G. 1981. Biology of Weeds in the Solanum nigrum Complex (Solanum Section Solanum) in North America. U.S. Department of Agriculture, Agricultural Reviews and Manuals, ARM-W-23.

© 2003 as to text; 2009 as to the image. Rufino Osorio. All rights reserved.

Saturday, August 22, 2009

Alan Cressler

Note: The images in this post are copyprighted by Alan Cressler with all rights reserved. They are used here with his permission.

© Alan Cressler.
Aquilegia canadensis – wild columbine.

Alan Cressler is a member of Flickr's digital image community whose employment and avocation afford him the luxury of extensive travel throughout the United States as well as foreign countries. In 1981, Alan became seriously interested in caves and, to date, he has explored almost 4,000 caves throughout the world. Fortunately for us, he enjoys photography nearly as much as he enjoys exploring caves and there are presently 4,380 images on his Flickr photostream, which is comprised of images of the flora and fauna associated with the various areas in which the caves he has visited are found. Equally fortunate is that many of the caves are located in pristine sites that harbor a rich diversity of unusual and interesting plants and animals. Alan's interests in natural history are quite broad and, besides landscapes, his images include lichens, ferns, mosses, wildflowers, shrubs, trees, cacti, reptiles, amphibians, crustaceans, insects, molluscs, grafitti (on cave walls), geologic features, waterfalls, traveling companions, and many other things that I am sure I have overlooked. However, for the readers of this blog, the highlight of Alan's photostream are the images of native plants, including many ferns and wildflowers of which photographic images are very rarely available, either in print or on the Internet. However, it is not merely the subject matter that is of interest, but also the quality of the photographs. Without exaggeration, Alan's work generally adheres to the highest standards of esthetic and technical excellence and it is some of the best natural history photography available on the Internet.

© Alan Cressler.
Dionaea muscipula – Venus flytrap.

Beautiful natural history images, no matter how esthetically pleasing, are not particularly useful unless the subjects are correctly identified and Alan takes great care to accurately identify whatever he photographs. To this end, he maintains a collection of hundreds of identification manuals, as well as having contact with professional scientists that can assist with particularly difficult identifications.

© Alan Cressler.
Hepatica acutiloba – sharp-lobed hepatica.

Flickr is a full-featured site and users have the ability to search Alan's images...a good thing indeed when there are over 4,300 of them to choose from! An additional aide to navigating this abundance of beautiful images is Alan's arrangement of some of the images into 120 different sets. The numerous sets allow viewers to focus on images of particular interest and some of the sets are extremely specific, such as one on just the tree snails of Florida or the one of just parasites. My favorite Flickr feature is the RSS feed and viewers can subscribe to Alan's photostream in an RSS reader. By subscribing to the RSS feed, one can be alerted whenever Alan posts new images, which, happily, is a frequent occurrence.

© Alan Cressler.
Panax quinquefolius – ginseng.


Alan's Flickr Photostream
Alan's Flickr Profile
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The Positive:

By way of his Flickr photostream, Alan provides viewers with a glimpse of unusual natural areas and their associated flora and fauna. Viewers are thus able to see and experience places, plants, and animals that would be difficult or expensive to view otherwise. Most images have been meticulously identified and images are generally artistically composed and excel in both esthetic and technical quality. Additionally, for most images, high resolution versions are available for download for noncommercial use. The natural flora and fauna of a region is respected and viewers are not encouraged to raise non-native animals or to cultivate non-native plants.

The Negative:

There are no negatives.

© Alan Cressler.
Zephyranthes atamasca – atamasco-lily.

As to text only: © 2009 Rufino Osorio.