All botany stories

Popular causes not necessarily best

jake — Mon, 22 Oct 2007 13:48:00 -0400

Conservation policies favoring keystone animal species are insufficient to conserve the world’s biodiversity because many of these target animals don’t live in the world’s most biodiverse spots: lowland tropical forests under pressure from agriculture, logging, and other human activities.

Trial Turns Over New Leaf for Traditional Herb

404132862 — Thu, 19 Jul 2007 13:58:08 -0400

If a painting’s worth were measured by the money it fetched, van Gogh’s famous rendering of his friend and physician Dr. Gachet would be among the most valuable in all of art. “Portrait of Dr. Gachet”—which depicts a languid man holding a purple foxglove, the plant from which the drug digitalis is derived—was sold in 1990 for an astounding 82 million dollars. The great and famously tortured artist had his own reasons for valuing the portrait. He suffered from severe epilepsy and depended heavily on Gachet’s prescription of digitalis to treat his debilitating seizures.

The ranks of epilepsy medications have expanded considerably in the past hundred years, due mostly to the addition of pharmaceutically derived compounds.

Ingenious use of indigenous tree reaps award

50443248 — Tue, 02 Oct 2007 12:38:17 -0400

The jatropha tree is a humble — some might even say homely — plant, with large, maple-like leaves and clusters of inedible fruit that, when mature, look too brown and shriveled to be of much use to anyone. But to thousands of rural eastern and southern Africans, the jatropha is a beautiful thing. It represents hope that they’ll someday have electric lamps to light their homes, refrigerators to keep medicines and vaccines cold in local clinics, and computers and telephones in the schools and orphanages — hope for sustainable energy. And on Tuesday (May 8), the people behind that hope were honored with the 2007 Roy Family Environmental Award in a day of events at the Kennedy School of Government (KSG).

Warming may not spark tree growth

Tue, 10 Jul 2007 15:21:22 -0400

A bright spot in the gloomy global warming picture has been scientists’ predictions that at least some carbon dioxide will be removed from the atmosphere by a burst of growth from tropical forests.

New research from the Arnold Arboretum, however, questions that prediction, finding that trees in two forests on opposite sides of the world have been growing dramatically slower, not faster, as temperatures have risen over the past 20 years.

Kenneth Feeley, a postdoctoral fellow at the Center for Tropical Forest Science, a partnership between the arboretum and the Smithsonian Tropical Research Institute, examined tree growth data from forest plots in Panama and Malaysia.

Figs likely first domesticated crop

Fri, 13 Jul 2007 10:14:57 -0400

Archaeobotanists have found evidence that the dawn of agriculture may have come with the domestication of fig trees in the Near East some 11,400 years ago, roughly 1,000 years before such staples as wheat, barley, and legumes were domesticated in the region. The discovery dates domesticated figs to a period some 5,000 years earlier than previously thought, making the fruit trees the oldest known domesticated crop.

Ofer Bar-Yosef of Harvard University and Mordechai E. Kislev and Anat Hartmann of Bar-Ilan University report their findings in this week's issue of the journal Science.

Invasive species harms hardwoods by killing soil fungus

70652986 — Mon, 26 Mar 2007 06:26:53 -0400

An invasive weed that has spread across much of the United States harms native maples, ashes, and other hardwood trees by releasing chemicals harmful to a soil fungus the trees depend on for growth and survival, scientists reported in the Public Library of Science.

The tree-stifling alien, garlic mustard (Alliaria petiolata), first introduced into the United States in the 1860s, has since spread to Canada and 30 states in the East and Midwest, with recent sightings as far west as Oregon.

While many mechanisms - from the absence of natural predators or parasites to the disruption of long-established interactions among native organisms - have been proposed to explain the success of invasive species, this new work is the first to show that an invasive plant harms native plants by thwarting the biological "friends" upon which they depend for growth. The work, which provides striking evidence for a unique process by which invaders harm native species, was conducted by researchers at Harvard University, the University of Guelph, the University of Montana, Purdue University, and the UFZ Centre for Environmental Research in Germany.

"While vanishing habitat caused by human activity is the number one threat to biodiversity, there is great concern over the impact of accidental and intentional dispersal of alien invasive species across the globe," says Kristina A. Stinson, a plant population biologist at the Harvard Forest, Harvard's ecology and conservation center in Petersham, Mass. "In North America, thousands of nonnative plants and animals have become established since European settlement and many more continue to be introduced. Some alien species cause little harm, while others can become very aggressive and radically transfigure their new habitat.

"The mechanisms for this phenomenon and its potential long- term impacts remain poorly understood," Stinson adds, "but one possibility is that invasive species may disrupt fragile ecological relationships that evolved over millions of years."

Eating plants that grow on plants

70652986 — Mon, 26 Mar 2007 06:26:23 -0400

Parasitic plants are not just a biological curiosity. Every year, parasitic plants damage farmers' fields, particularly in Africa. Kristin Lewis, a junior fellow at the Rowland Institute at Harvard, is learning more about plants and their parasites.

For instance, in Africa, seeds of parasitic plants blow in from surrounding environments or are deposited in bird droppings. The plants that grow from those seeds attach to roots and stems, sucking vital nutrients, stunting the crop plants' growth, and reducing yields.

To foil the parasites, African farmers have adopted the practice of planting fields twice, first with plants that are resistant to the parasites and then, after the parasites germinate and die, with their desired crop, such as sorghum.

"Most of them are very problematic plants," Lewis said.

Lewis became interested in parasitic plants while studying plant defenses. Though they can't fight back as an animal would, plants can generate a wide variety of substances that are toxic or distasteful to insects and other browsers.

In fact, some of our best-known commercial plants are popular exactly because of the unique qualities of the plant's chemical defenses. Caffeine and nicotine, for example, as well as the hot spices contained in pepper plants, are all intended by the plant to discourage herbivores.

After studying plants' reactions to insects eating their leaves, Lewis became interested in the interaction of a plant and its parasite.

She already knew that in some cases a parasitic plant shares the host plant's defensive chemicals, as well as nutrients and carbohydrates. What she wants to find out is how much the two plants communicate.

If an insect attacks a parasitic plant, that insect is just a short distance from the host plant. Though normally the host wouldn't benefit from helping its parasite, it's possible the parasite could manipulate the host into shifting more defensive chemicals into the parasite to keep the leaf-eating insect at bay - over there. That would require some sort of communication from the parasite to the host saying, in essence: "Send help fast. It's BITING me!"

Lewis said she's still gathering data, but she remains fascinated by the active responses to the environment of plants, which on the surface seem so passive.

Harvard 'Foresters' put forward bold new plan

50443248 — Tue, 24 Jul 2007 13:13:33 -0400

n a new scientific report titled "Wildlands and Woodlands: A Vision for the Forests of Massachusetts," David Foster, director of Harvard University's Harvard Forest, is calling, along with his colleagues, for a bold new land protection effort to stave off accelerating forest fragmentation in Massachusetts. "The time has come to step up to the challenge of protecting the commonwealth's forest infrastructure," said Foster.
The scientists cite forest loss statistics, such as the fact that Massachusetts is losing open space to development at a rate of 40 acres each day, and call for:

Snaring secrets of the Venus flytrap

70652986 — Mon, 26 Mar 2007 05:36:21 -0400

While "speed" is not a word most people associate with the plant kingdom, the Venus flytrap closes its v-shaped leaves in just one-tenth of a second - fast enough to accomplish a feat thousands if not millions of backyard barbecuers fail at each summer: snaring a fly. So how can a plant pull this off? By storing and releasing elastic energy, according to Gordon McKay Professor of Applied Mathematics and Mechanics Lakshminarayanan Mahadevan. Mahadevan likened the Venus flytrap's hinged leaves to a plastic lid that is bowed in one direction and then suddenly pops the other way. While waiting for prey, the plant's leaves are bowed outward, opening the hinged trap. When an insect touches the hairy triggers located inside of the trap, the plant moves water in the leaves, changing their curvature and suddenly snapping them closed. "It is a relatively simple mechanism, but the plant is actively controlling it," Mahadevan said. The plant then excretes digestive enzymes that break down the meal, providing nutrients that the plant cannot get from the poor, boggy soil where it grows naturally. The research, published in the Jan. 27, 2005 issue of the journal Nature, was conducted largely while Mahadevan was at the University of Cambridge before coming to Harvard in 2003.

Missy Holbrook investigates the world of plants

70652986 — Mon, 26 Mar 2007 05:26:03 -0400

Every day an oak tree moves hundreds of gallons of water up from the soil and out, in evaporated form, through its leaves. "Mechanically, it's a pretty substantial feat," says Professor Missy Holbrook. "They do it very quietly, with no moving parts, but you'd be hard-pressed yourself to get that much water out of the soil and into the atmosphere." Learning how plants move water has implications for agricultural productivity, but also for problems in engineering. For several years, Holbrook and her colleagues have studied the long-distance transport of water, as well as sugar, in plants.

Battling toxic molds

70652986 — Mon, 26 Mar 2007 05:23:26 -0400

Molds are found in all kinds of environments. Estimates of the number of kinds of molds range from tens of thousands to more than 300,000, with more than 1,000 species known to typically grow indoors, according to the Centers for Disease Control and Prevention. While many molds appear to be benign to humans -- and some, such as the kind that produces penicillin, are beneficial -- several species are considered to be potent toxins. Questions raised by molds interest Mike Muilenberg, research associate and instructor in the Department of Environmental Health at Harvard's School of Public Health. As part of a series of studies on indoor allergens, Muilenberg is looking at the relationship between mold and health.

Pollen production -- and allergies -- may rise significantly over next 50 years

70652986 — Mon, 26 Mar 2007 05:20:19 -0400

Ragweed, which flourishes along roadsides and in disturbed habitats throughout North America, produces one of the most common allergens. A study by Harvard researchers found that ragweed grown in an atmosphere with double the current carbon dioxide levels produced 61 percent more pollen than normal. Such a doubling of atmospheric carbon dioxide is expected to occur between 2050 and 2100. "The side effects of carbon dioxide, as well as its impact on heat budget and the water cycle, have to be taken very seriously," said Paul Epstein, Harvard Medical School instructor in medicine and associate director of the Center for Health and the Global Environment at HMS.

Oldest known flowering plants identified by genes

70652986 — Mon, 26 Mar 2007 05:05:07 -0400

Flowering plants now number 250,000 different species, including virtually all the vegetables and grains we eat, as well as most of the food of the animals that we consume. "It's difficult to imagine a world without flowering plants," said researcher Michael Donoghue. In 1999, as a result of analyzing the genes from all flowering plants suspected of being among the world's oldest, Donoghue and research associate Sarah Mathews concluded that Amborella and water lilies are the first two branches on the family tree of flowering plants. Amborella is a nondescript shrub with small, unimpressive flowers, and it is found in only one place in the world – New Caledonia, a minor tropical island in a remote corner of the southwest Pacific.

Saving plants that may save us

70652986 — Mon, 26 Mar 2007 05:11:19 -0400

One particular discovery highlights the importance of facilities like the Harvard Herbaria and Arnold Arboretum in storing and preserving the important information found in plants. An extract of a small tree in the Bornean forest called Calophyllum stopped AIDS, but when researchers rushed back to the site where it had been collected, the tree had already been cut down. Researchers took samples from Calophyllum trees nearby, but extracts made from those trees proved ineffective against the AIDS virus. To solve the mystery, researchers called on the Harvard Herbaria, which had a preserved sample from the original tree. Once they knew what they were looking for, scientists found living specimens of the right Calophyllum variety in the Singapore Botanic Garden.