Pick up know-how for tackling diseases, pests and weeds.
Farm bill, farm marketing, agribusiness webinars, & farm policy.
Find tactics for healthy livestock and sound forages.
Scheduling and methods of irrigation.
Explore our Extension locations around the state.
Commercial row crop production in Arkansas.
Agriculture weed management resources.
Use virtual and real tools to improve critical calculations for farms and ranches.
Learn to ID forages and more.
Explore our research locations around the state.
Get the latest research results from our county agents.
Our programs include aquaculture, diagnostics, and energy conservation.
Keep our food, fiber and fuel supplies safe from disaster.
Private, Commercial & Non-commercial training and education.
Specialty crops including turfgrass, vegetables, fruits, and ornamentals.
Find educational resources and get youth engaged in agriculture.
Gaining garden smarts and sharing skills.
Timely tips for the Arkansas home gardener.
Creating beauty in and around the home.
Maintenance calendar, and best practices.
Coaxing the best produce from asparagus to zucchini.
What’s wrong with my plants? The clinic can help.
Featured trees, vines, shrubs and flowers.
Ask our experts plant, animal, or insect questions.
Enjoying the sweet fruits of your labor.
Herbs, native plants, & reference desk QA.
Growing together from youth to maturity.
Crapemyrtles, hydrangeas, hort glossary, and weed ID databases.
Get beekeeping, honey production, and class information.
Grow a pollinator-friendly garden.
Schedule these timely events on your gardening calendar.
Equipping individuals to lead organizations, communities, and regions.
Guiding communities and regions toward vibrant and sustainable futures.
Guiding entrepreneurs from concept to profit.
Position your business to compete for government contracts.
Find trends, opportunities and impacts.
Providing unbiased information to enable educated votes on critical issues.
Increase your knowledge of public issues & get involved.
Research-based connection to government and policy issues.
Support Arkansas local food initiatives.
Read about our efforts.
Preparing for and recovering from disasters.
Licensing for forestry and wildlife professionals.
Preserving water quality and quantity.
Cleaner air for healthier living.
Firewood & bioenergy resources.
Managing a complex forest ecosystem.
Read about nature across Arkansas and the U.S.
Learn to manage wildlife on your land.
Soil quality and its use here in Arkansas.
Learn to ID unwanted plant and animal visitors.
Timely updates from our specialists.
Eating right and staying healthy.
Ensuring safe meals.
Take charge of your well-being.
Cooking with Arkansas foods.
Making the most of your money.
Making sound choices for families and ourselves.
Nurturing our future.
Get tips for food, fitness, finance, and more!
Understanding aging and its effects.
Giving back to the community.
Managing safely when disaster strikes.
Listen to our latest episode!
Cacti Invsaion
My travels during the week took me from the north rim of the Grand Canyon to a “cabin” in the woods just below the Mogollon Rim in northern Arizona where Whinny and I spent the weekend with my brother and his wife at about 6,000 feet in the cool, clear air. The holiday visit was planned but the dented and leaking transmission oil pan was not. Probably hit a rock in one of my back-country adventures.
The Mogollon Rim is the southernmost expanse of the Colorado Plateau, which I have been traversing for the past several weeks. On Saturday we drove off of the rim into the valley below, going from comfortable 70-degree weather to a blazing 105. But, as they say, it’s a dry heat.
I had been encountering cacti (all were species of Opuntia) on my hikes around the Colorado Plateau, but when I dropped into the desert floor of Arizona, they took on a whole new dimension. Instead of sprawling clumps hiding in the undergrowth, cacti became a dominant feature of the landscape. Most noticeable were the saguaros (Carnegiea gigantea), the iconic armed cacti featured on the Arizona license plate.
The saguaros usually stand 30 feet or so tall with a few too many arms and dominate the lower hillsides where temperatures seldom get below 20 degrees in the winter. Hunkered around them are chest-high Opuntia species that provide a more impressive display than the sprawling kinds I had been seeing in the high, dry interior of the Colorado Plateau. Some southern Arizona counties have as many as 50 species growing there.
These cacti are new to this country. Well, relatively new. Because cacti fossils have never been found, there has been considerable debate about the evolutionary history of the cactus family. Current speculation is that the family had its beginnings about 30 million years ago in northern South America when that region saw a drying trend as the Andes Mountains began to rise. Diversification of form reached its peak between 5 and 10 million years ago, when drought became a dominant feature as the Andes reached their full height and desertification took hold.
Interestingly, it was not until about 5 million years ago that an offshore island — now we call it Panama — was shoved into the gap by tectonic forces between North and South America and cacti arrived here. When this land bridge was in place all manner of plants and animals migrated onto the new landmass. Because much of Central America, Mexico and the southwestern region of this continent were xeric, cacti proved especially well-suited for the new homeland.
The two major divisions of the cactus family are the true cacti (about 75 percent of the 1,750 known species) and the opuntia (most of the rest). It is not clear to me if the opuntia migrated first into North America and picked up freeze tolerance along the way, or if the true cacti just lacked the genes for freeze resistance. At any rate, the opuntia spread throughout the land and are found in every state and most Canadian provinces, whereas the true cacti are mostly limited to the milder sections of the desert southwest. A few ball cacti have ventured into colder climates, but they are the exception and don’t have the same degree of freeze tolerance as the opuntia.
This period in Earth’s history was a dry time across much of the continent and desert-adapted species, unrelated to cacti, began to appear in Australia, Africa and other arid regions around the world. From the human perspective, five million years is a long time, but it took our species only 10,000 years to go from the rise of agriculture to world domination. Maybe not so long after all.
Gerald Klingaman is a retired Arkansas Extension Horticulturist and retired Operations Director for the Botanical Garden of the Ozarks. After more than two decades of penning the popular Plant of the Week column, he’s taking a new direction, offering views on nature as he pokes about the state and nation. Views and opinions reflect those of the author and are not those of the University of Arkansas System Division of Agriculture. If you have questions or comments for Dr. Klingaman about these articles contact him at musingsonnature@gmail.com.