Cactus, Fleshy Plants Native to America

Cactus, common name for the family comprising a peculiar group of spiny, fleshy plants native to America. The family contains about 1650 species, most of which are adapted to arid climates. The fruits of cacti are important sources of food and drink in many areas to which they are native. Because cacti require little care and exhibit bizarre forms, they are popular for home cultivation and are coming under increasing pressure as a result. More than 17 kinds of cacti now face extinction (see Endangered Species) because of plundering by avid collectors and professional poachers, especially in the southwestern United States and northern Mexico.

Cactus plants usually consist of spiny stems and roots. Leaves are greatly reduced or entirely absent. Only in two genera are fully formed leaves present. The stems of cacti are usually swollen and fleshy, adapted to water storage, and many are shaped in ways that cause rain to flow directly to the root system for absorption. The roots form extensive systems near the soil surface, assuring that a given plant will absorb the maximum amount of water from a wide area; plants in deserts are usually widely spaced.

The most distinctive vegetative feature of cacti is the areoles, specialized areas on the stems on which stiff, sharp spines usually grow. Some cacti lack spines but have hairs or sharp, barbed structures called glocids on the areoles. Areoles develop from lateral buds on the stems and appear to represent highly specialized branches.

The flowers of cacti are often large and showy and occur singly rather than in clusters of several flowers. The perianth (floral tube) does not consist of sharply differentiated sepals and petals, but rather of a series of bracts (modified leaves), which gradually grade into sepals and finally into showy petals. The flowers have many stamens; the ovary is inferior and fused to the perianth. The fruits are often brightly colored and fleshy.

Most of the 130 or so genera of cacti are found in cultivation, the small, slow-growing species being most popular because of their variety in shapes, colors, and spines. One of the best-known is a group containing beautiful night-blooming flowers and the familiar saguaro plant. In some classifications, this group is split into as many as 10 separate genera (see Cereus). Still more widely grown is the group containing the Christmas cactus. Species of this group, which naturally occur as epiphytes (air plants) in tropical rain forests, do not fit the popular idea of cacti as squat, fleshy plants of desert regions. Examination of their stems, however, reveals the presence of the cactus family’s unique areoles; their flowers have the typical cactus features.

Many groups of plants that are unrelated to cacti have also adapted to survive in arid regions and often resemble cacti in appearance. These offer examples of parallel evolution: Unrelated organisms subjected to similar environmental stresses often evolve similar anatomical and functional characteristics. For example, many spurges that grow in dry parts of Africa, where cacti are not found, exhibit leafless, spiny, fleshy stems (see Spurge).

Scientific classification: Cacti make up the family Cactaceae. Cacti with fully formed leaves are classified in the genera Pereskia and Pereskiopsis. The night-blooming flowers and the saguaro plant are classified in the genus Cereus. The Christmas cactus is classified as Schlumbergera bridgesii.

How to Managing Compost?

A variety of techniques may be used to increase the rate of compost decomposition. One technique is to cut the starting materials into 10- to 15-cm (4- to 6-in) pieces to increase the surface area on which the microorganisms act. Increased surface area accelerates decomposition, much like a large ice chunk melts faster if broken up into small pieces. The microorganisms in the compost pile also thrive when oxygen and moisture are present. Fluffing the compost pile every week or so with a pitchfork or other tool introduces oxygen into the pile, and sprinkling water on the pile when it dries out provides the necessary moisture.

In a well-managed compost pile, the microorganisms eat and reproduce rapidly, and heat is released as a byproduct of their intense biochemical activity. The heat in the pile kills most plant diseases and weed seeds that may have been present on the starting materials. The increased heat may also kill the microorganisms doing the decomposing as well, especially those at the center of the pile where temperatures may climb to 90° C (200° F). Mixing the materials well about once a week prevents lethal temperature increases by distributing the heat evenly throughout the pile.

The time it takes microorganisms to decompose the starting materials in compost varies. Factors include the size of the pile, the techniques used to manage the pile, and the nature of the starting materials—green materials decompose readily, while brown materials take longer to break down. In an actively managed compost pile, microorganisms use up their food supply and become less active after about six weeks. Then the pile slowly cools, signaling the near-final stages of decomposition. If the materials in a compost pile are relatively large, if the pile is not kept moist, and if oxygen is not introduced, microorganism activity is slow and the pile does not heat up. Depending upon the climate, it may take months or years for decomposition to occur.
No matter how long decomposition takes, when in its final stage, the compost pile is about half its original size and resembles dark soil. The material in the pile is now called humus—although the terms humus and compost sometimes are used interchangeably. Humus is the highly beneficial material that is added to the garden soil. Once in or on the soil, it continues to decompose at a very slow rate, releasing ammonia, carbon dioxide, and salts of calcium, phosphorus, and other elements that are beneficial for plant growth.

Humus can be added to the soil at any time of year. It can be worked into the soil, where its benefits take effect most rapidly, or it can be left on the soil surface. Humus can be used year after year, and there is never danger of adding too much, since this remarkable substance only enhances soil and encourages plants to thrive.

Cities compost on a large scale to reduce yard waste so that it does not take up space in landfills. Industries compost hazardous materials because the activities of the microorganisms help break down toxic substances into less-harmful or harmless materials. Many municipalities provide information on composting as part of their programs to reduce the amount of solid waste entering their landfills. County or regional offices of the state Cooperative Extension Service also have information on composting.

How to Making Compost?

Compost is made by harnessing the natural decomposition process carried out by certain species of microorganisms. These microorganisms, primarily bacteria and fungi, live in intimate association with their food supply—on the surface of dead plants, in soil, or on or in animal waste. By breaking down these materials with their digestive enzymes, the tiny creatures release and absorb the nutrients within. For home gardeners, making compost is simply a matter of collecting food for microorganisms in one place and letting them go to work.

A broad range of organic matter, including manure from plant-eating animals, grass clippings, and dead leaves or garden plants, provides a veritable feast for microorganisms. For optimal decomposition, the combined starting materials should have an appropriate carbon to nitrogen ratio, preferably 30 parts carbon to 1 part nitrogen. Leaves, straw, and paper, called brown materials, have a high carbon to nitrogen ratio, about 300 to 1, while grass clippings, kitchen scraps, and manure, called green materials, have a low carbon to nitrogen ratio, about 15 to 1. For the best mix, green materials should be added in abundance; brown materials should be used more sparingly. Materials that should not be used to make compost include manure from meat-eating animals, because it may contain disease-causing organisms that can harm humans who eat plants grown in the compost. Meat should be avoided since it may attract rodents. Fatty foods such as cheese also should not be added to the compost pile, as they are hard for most microorganisms to digest.

The starting materials are heaped into a pile—in a home garden, the pile is typically about a meter high and a meter wide (about three feet high and three feet wide); on farms, composting is done on a larger scale. The pile may sit loose on the ground or it may be enclosed using a variety of materials, including wire fencing, wood boards, cinder blocks, or widely stacked bricks.

Unique Plant (Parnassia fimbriata)

A bit of BPotD news before today"s entry: we finally have a date and time set to transition the web site over to the new server. It"s been a real headache for months, but hopefully the pain will be over by mid-week next week. On Monday @ 10am local time, we"ll start to move the site over. Unfortunately, since we"re also moving to a new server, the web site domain name needs to be pointed to the new server, and that means it appears to be a couple days before you are able to access content on the new site while the name propagates to the various Internet Service Providers. The old site will still be running for a few days, but comments will be turned off. Fingers crossed that all goes well!

The last time I featured a Parnassia on BPotD (over 5 years ago: Parnassia glauca), I wrote that the genus had been moved out of the Saxifragaceae (you"ll see that in a number of classification systems) and even out of the Saxifragales (the order containing the Saxifragaceae and related families) and into the Parnassiaceae (within the Celastrales). Many research groups have since studied the relationships between Parnassiaceae and Celastraceae; current thought provisionally places Parnassia within the Celastraceae, but it seems (after reading the Phylogeny section on the linked page) that this may yet revert to being split again.

This August photograph of Parnassia fimbriata (fringed grass-of-Parnassus or Rocky Mountain grass-of-Parnassus) was taken only meters away from a second of British Columbia"s four Parnassia species, Parnassia kotzebuei. Parnassia is another genus I am always thrilled to encounter, as it was one of the first dozen or so I learned to recognize in Manitoba.

Parnassia fimbriata is native to much of western North America, where it grows in moist sites (fens, bogs, streamside, seeps, wet meadows) at elevations ranging from lowland to alpine. It is the tallest of these herbaceous species in British Columbia, occasionally reaching 50cm in height (though more typically 15 to 30cm). Parnassia kotzebuei, by comparison, is the shortest, ranging from 6-20cm.

Parnassia is a reference to Mount Parnassus; Linnaeus applied the name to the genus based on an account in Materia Medica, a written work by the Greek doctor Dioscorides (Dioscorides called it Agrostis En Parnasso). The Plants for a Future database contains a listing of historical medicinal uses for Parnassia palustris, the species thought to have been described by Dioscorides (who also said of it: "That which grows in Cilicia (which the inhabitants call cinna) inflames rude beasts if often fed on when it is moist".

For additional photographs, see Calphotos: Parnassia fimbriata or Southwest Colorado

Wildflower Colors Tell Butterflies How to Do Their Jobs

The recipe for making one species into two requires time and some kind of separation, like being on different islands or something else that discourages gene flow between the two budding species. In the case of common Texas wildflowers that share meadows and roadside ditches, color-coding apparently does the trick.

Duke University graduate student Robin Hopkins has found the first evidence of a specific genetic change that helps two closely related wildflowers avoid creating costly hybrids. It results in one of the normally light blue flowers being tagged with a reddish color to appear less appetizing to the pollinating butterflies which prefer blue.

"There are big questions about evolution that are addressed by flower color," said Hopkins, who successfully defended her doctoral dissertation just weeks before seeing the same work appear in the journal Nature.

What Hopkins found, with her thesis adviser, Duke biology professor Mark Rausher, is the first clear genetic evidence for something called reinforcement in plants. Reinforcement keeps two similar proto-species moving apart by discouraging hybrid matings. Flower color had been expected to aid reinforcement, but the genes had not been found.

In animals or insects, reinforcement might be accomplished by a small difference in scent, plumage or mating rituals. But plants don't dance or choose their mates. So they apparently exert some choice by using color to discourage the butterflies from mingling their pollen, Hopkins said.

Where Phlox drummondii lives by itself, it has a periwinkle blue blossom. But where its range overlaps with Phlox cuspidata, which is also light blue, drummondii flowers appear darker and more red. Some individual butterflies prefer light blue blossoms and will go from blue to blue, avoiding the dark reds. Other individual butterflies prefer the reds and will stick with those. This "constancy" prevents hybrid crosses.

Hybrid offspring between drummondii and cuspidata turn out to be nearly sterile, making the next generation a genetic dead-end. The persistent force of natural selection tends to push the plants toward avoiding those less fruitful crosses, and encourages breeding true to type. In this case, selection apparently worked upon floral color.

Hopkins was able to find the genes involved in the color change by crossing a light blue drummondii with the red in greenhouse experiments. She found the offspring occurred in four different colors in the exact 9-to-3-to-3-to-1 ratios of classical Mendelian inheritance. "It was 2 in the morning when I figured this out," she said. "I almost woke up my adviser."

From there, she did standard genetics to find the exact genes. The change to red is caused by a recessive gene that knocks out the production of the plant's one blue pigment while allowing for the continued production of two red pigments.

Even where the red flowers are present, about 11 percent of each generation will be the nearly-sterile hybrids. But without color-coding, that figure would be more like 28 percent, Hopkins said. Why and how the butterflies make the distinction has yet to be discovered.

Hopkins will be continuing her research as a visiting scientist at the University of Texas, and the clear message from all of her advisers is "follow the butterflies. Everyone wants to know more about the butterflies!"

The research was supported by grants from the National Science Foundation.

Source

Ten Most Wanted Plants

Students, gardeners, retirees and other volunteers across the nation who are taking part in a nationwide initiative--Project BudBurst--are finding hints that certain plants are blooming uncommonly early, perhaps as a result of climate change.

The citizen researchers are recording the timing of flowers and foliage, amassing thousands of observations from across the nation to give scientists a detailed picture of our changing climate.

The project, which started as a pilot program in 2007, now focuses on a list of the "10 most wanted species"--flowers and trees such as the common lilac, red maple and Virginia bluebell.

Such widely distributed plants can provide important early signs of the impact of warming temperatures on the environment, as per the researchers who designed the project.

"Project BudBurst empowers people living anywhere in the country to make a contribution that will lead to better understanding of our environment," said Project BudBurst director Sandra Henderson of the University Corporation for Atmospheric Research (UCAR) Office of Education and Outreach. "This is needed data to help researchers who are studying the impacts of climate change".

Project BudBurst is operated by UCAR and the Chicago Botanic Garden, and is a partner in the USA National Phenology Network.

Funding comes from the National Science Foundation (NSF), along with the U.S. Fish and Wildlife Service, U.S. Geological Survey, U.S. Forest Service, National Ecological Observatory Network, NASA and the National Geographic Education Foundation.

"While these observations may reveal impacts of climate change in local areas, researchers need data from a number of more locations," said Elizabeth Blood, program director in NSF's Directorate for Biological Sciences, which funds Project BudBurst. "Researchers also need more years of data to understand changes over larger regional scales, as well as distinguish the effects of long-term trends in climate from natural year-to-year variations".

In Chicago, volunteers who have observed 15 kinds of plants since 2007 have observed that seven of them are flowering earlier now than at any time in more than 50 years of observations by botanists.

"We will need volunteers to make observations for many years before we can fill in an accurate picture about the impact of climate change on our landscape," Henderson says.

Volunteers say they enjoy making the observations.

"Where there are curious people, it doesn't take long to bring together a group to go scrutinizing particular plants and trees, discovering the earliest stages of cones or bud formation, for instance, then following the later development," said Sue Prindle, who lives in a retirement community in Silver Spring, Md. "It has been rewarding and fun".

Overall, participants across the country have made more than 10,000 observations since 2007, establishing a baseline for the timing of key plant events.

"These findings are important as researchers analyze the impacts of global warming on our natural world," says Kayri Havens, a senior scientist with the Chicago Botanic Garden and co-manager of Project BudBurst.

Each participant in Project BudBurst selects one or more plants to observe.

The Project BudBurst Web site encourages volunteers to focus on the 10 most wanted species, but it also welcomes observations of other plants.

Volunteers begin checking their plants at least a week previous to the average date of budburst--the point when the buds have opened and leaves are visible.

After budburst, participants continue to observe the tree or flower for later events, such as seed dispersal and autumn leaf dropoff. Participants submit their records of these phenophases online.

Anyone can view the results as maps of the phenophases across the United States.

The science of phenology, or tracking cyclic behavior among plants and animals, has a distinguished history.

For centuries farmers, naturalists, geographers and others have kept careful records of the phenology patterns of plants and animals.

Farmers have long used their phenology knowledge to predict the best time for planting and harvesting crops, when to start expecting problems with insect pests, and other seasonal events.

The effects of climate change on numerous plant and animal species throughout the world have been observed and published in the scientific literature.

Some plants respond to warmer temperatures by extending their growing seasons. Others shift their ranges toward the poles or to higher elevations.

At the same time, a number of insects breed and disperse based on regular cycles of sunlight rather than temperature.

This can cause a mismatch between the behavior of pollinating insects, such as bees, and flowers that bloom earlier than the insects expect. Such asynchronous behavior has already been noted across a number of parts of the world.

Source

Growing Alliums - Ornamental Onions

Overview:

There are hundreds of alliums, including the onions and garlic we eat. The ornamental varieties often have leaves similar to onions, as well as the onion’s round ball shaped flower heads. However there are many varieties with star-like clusters of flowers and others, like A. Cernuum, the ‘Nodding Onion’, with hanging pendants of blossoms.

Latin Name :Allium

Common Name(s): Ornamental Onion

Zone: 4-10

Size: 5 - 60" H, 3 - 12" W

Exposure: Full sun

Bloom Period/Days to Harvest : Varies with variety

Description:

Alliums grow from bulbs. They have strappy, undistinguished leaves and straight tubular flower stalks. The flower form in clusters and are best known in the round pom-pom form, but they can be start shaped, cup-shaped, semi-circular or pendulous.

Cultural Notes:

Plant the bulbs in autumn, for bloom the following season. Alliums are not prone to many problems except certain rots, if conditions are too wet. Even deer don’t like alliums.

Maintenance: Alliums do not repeat bloom. Flower heads can be left on the plant to dry. The dried seed heads look attractive in the garden and can be cut for arrangements. Keep foliage watered after flowering, to feed the plant.

Design Tips:

The lollipop shape of the flowers looks charming poking through low growing mats such as hardy geraniums. The shape also works well with other medium height plants like foxglove, that provide a form contrast or Monarda, which provides a form echo.

Suggested Varieties:

• A. giganteum - Very dramatic softball size flower clusters on 5-6' stems.
• A. ‘Purple Sensation’ - Very dependable. Nice mid-spring color.
• A. cernuum. - The ‘Nodding Onion’. Pretty pink, pendent umbels of flowers.

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