by Carrie Stevenson | Jun 4, 2020
Sundews, tiny carnivorous plants found in pitcher plant bogs, use an enzyme dissolve insect proteins. Native Americans recognized this property and used the plant for skin maladies. Photo credit: Carrie Stevenson, UF IFAS Extension
There are few words better than “pure delight” to describe the face of someone who sees and appreciates a sundew for the first time. Maybe it is their size—often no bigger around than a quarter—or the miniature pinwheel shape, but sundews could easily fit into a fable about garden gnomes or fairies in the woods. These tiny plants hide in plant sight–so small and flush to the ground that you likely won’t see them unless specifically looking for them. But, once you are looking in the right conditions, you will probably see them everywhere.
Sundews (Drosera spp.) are small carnivorous plants found in the same bogs as pitcher plants. They thrive in moist, mucky soil and full sun. They are also carnivorous for the same reasons pitcher plants are—their wet, acidic habitats possess few soil nutrients, so they use insects instead.
Sundews utilize a different method for trapping insects—their flat, radiating structure has wider lobes on the ends, which are covered with hairlike tentacles. These hairs secrete droplets of sticky sap visible at the tip of each hair. Small insects are attracted to the dewlike sap and get stuck. The hairs curl around the insect like a slow Venus flytrap, and natural enzymes to break down the bug.
A healthy sundew plant growing just above the water level at Boiling Creek in Santa Rosa County. Photo credit: Larry Burner, Florida Master Naturalist
There are almost 200 species of sundews, not all with the flat growth pattern. The threadleaf sundew has an upright structure, while others may grow in a spherical shape at the water’s edge. While paddling Boiling Creek on Eglin Air Force Base property a few years ago, our group saw dozens of sundews growing on the trunks of cypress and tupelo trees at eye-level from our kayaks. They were about 4-6” in diameter, much larger than the 1” ones we typically see in the bogs.
Tarkiln State Park, Weeks Bay National Estuarine Research Reserve, or any place you find pitcher plants are a great place to find sundews. You may have to get on your knees to see them, and move the grasses aside. Bring a hand lens to magnify the delicate details of the droplets of sap perched at the tip of tiny hairs.
Even the famous naturalist Charles Darwin was enthralled with sundews, conducting experiments and writing volumes about them. In an 1860 letter to his geologist friend Charles Lyell, Darwin stated that, “at the present moment, I care more about Drosera than the origin of all the species in the world.” If you, too, are fascinated with carnivorous plants, check out these resources from UF IFAS Extension and the Botanical Society of America.
by Carrie Stevenson | Jun 4, 2020
Fig. 1 An adult redbay ambrosia beetle compared to the size of a single penny. Credit: UF/IFAS File Photo.
While most bark beetles are important in forest ecology by recycling fallen dead trees and eliminating sick and damaged trees, some of them may impact healthy trees. A group of bark beetles that has become a major concern to forest managers, nurseries, and homeowners is the ambrosia beetle. Ambrosia beetles are extremely small, 1-2 mm in length, and live and reproduce inside the wood of various species of trees (Fig. 1). Ambrosia beetles differ from other bark beetles in that they do not feed directly on wood, but on a symbiotic fungus that digests wood tissue for them. Every year, non-native species of ambrosia beetles enter the United States through international cargo and we have now nearly forty non-native species of ambrosia beetles confirmed in the United States. Among them, the redbay ambrosia beetle (Xyleborus glabratus), originally from Southeast Asia, is the vector of the fungal pathogen causing laurel wilt, a disease that devastated the Lauracaea population in the southeastern USA, killing millions of redbay, swamp bay, sassafaras and silk bay.
Fig. 2: A mature dooryard avocado tree with large sections of dead and missing leaves, caused by laurel wilt disease. Summer 2009 Impact Magazine image. Credit: UF/IFAS File Photo.
When these beetles attack a laurel tree, the symbiotic fungus is vectored to the tree’s sapwood after the beetle has tunneled deep into the tree’s xylem, actively colonizing the tree’s vascular system. This colonization leads to an occlusion of the xylem, causing wilting of individual branches and in a matter of weeks progresses throughout the entire canopy, eventually leading to tree death (Fig. 2). The laurel wilt disease has spread rapidly after the vector was first detected in Georgia in 2002. The redbay ambrosia beetle was first detected in Florida in 2004, in Duval County, attacking redbay and swamp bay trees. At this point, it is estimated that more than one-third of redbay in the U.S.A., 300 million trees, have succumbed to the disease.
Starting in 2017, we examined the efficacy of verbenone against redbay ambrosia beetle in live laurel trees in a natural forest setting. Verbenone is an anti-aggregation pheromone that has been used since the 1980’s to protect lodgepole pine. Verbenone also has the potential to be used over large areas and is currently being used to protect ponderosa pine plantations from the Mountain Pine Beetle in the western US.
We have found verbenone to be an environmentally friendly and safe tool to prophylactically protect laurel trees against redbay ambrosia beetle. Our protocol consists of the application of four 17 g dollops of a slow-release wax based repellent (SPLAT Verb®, ISCA technology of Riverside, CA) to the trunk of redbay trees at 1 – 1.5 m above ground level (Fig. 3). The wax needs to be reapplied every 4 months during fall and winter and every 3 months during spring and fall when temperature is higher. When compared to the control trees without repellents, we found that trunk applications of verbenone reduced landing of the redbay ambrosia beetle on live redbay trees and increased survivorship of laurel trees compared to untreated trees (Fig. 4). Verbenone should be considered as part of a holistic management system against redbay ambrosia beetle that also includes removal and chipping of contaminated trees.
If you have Redbay or other bay species on your property and are concerned about Laurel Wilt Disease or Redbay Ambrosia Beetle damage, contact your local UF/IFAS Extension Agents for help!
This article is courtesy of Dr. Xavier Martini and Mr. Derek Conover of the UF/IFAS North Florida Research and Education Center (NFREC) in Quincy.
Fig. 3: Application of SPLAT Verb on a redbay tree during a field trial
Figure 4: (A): Cumulative capture of redbay ambrosia beetles Xyleborus glabratus following a single application of verbenone vs untreated control (UC). (B) Survivorship of redbay and swamp bay trees treated with verbenone on four different studies conducted in 2017 and 2018.
by Carrie Stevenson | Apr 30, 2020
White-topped pitcher plants in bloom at Tarkiln State Preserve. Photo credit: Carrie Stevenson, UF IFAS Extension
If you live in northwest Florida or southeast Alabama and have never laid eyes on our wild native carnivorous plants, it is about time! April and early May are the best times to see them in bloom. We have six species of pitcher plants (Sarracenia), the most common being the white-topped (Sarracenia leucophylla). However, they come in multiple colors, from yellow and red to a deep purple, and in different sizes.
One thing they all have in common, though—they eat meat. Carnivorous plants all over the world have evolved in places that left them few other options for survival. These plants are typically found in extremely wet, acidic, mucky soils with very low nutrient levels. Normally, plants uptake nutrients like nitrogen and phosphorus from the soil around them. Not being available in these particular environments, carnivorous plants (or more specifically, insectivorous) developed a way to extract nutrients from insects.
Small parrot pitcher plants lie on the ground instead of standing upright at Blackwater State Forest. Photo credit: Carrie Stevenson, UF IFAS Extension
So how does it work? Pitcher plants have a modified leaf, which instead of lying out flat like most plants, is rolled up into a tube, or “pitcher” shape. The inside of the pitcher has a sweet sap, and the walls of the tube are lined with tiny, downward-pointing hairs. Separate from the leaf, the plant has an elaborate flower structure, which attracts insects for pollination. While nearby, these insects are also attracted to the colorful leaf and the sweet sap in its pitcher. The insect will land on the lip of the leaf, then crawl down.
A lizard waits patiently a the bottom of a pitcher plant, hoping to catch insect prey. Photo credit: Carrie Stevenson, UF IFAS Extension
Those sticky, downward facing hairs are a trap, preventing insects from leaving the pitcher. Enzymes—a cocktail of proteins naturally found in many other plants but used creatively here—in the sap break down the bug bodies and convert them to nutrients for the plant. In fact, if you slice a cross-section into a pitcher wall or break open a dried one, you will see countless dried exoskeletons at the bottom of the tube. Several other enterprising species have taken advantage of the pitcher plant’s creative structure. More than once, I have seen tiny spiders spin webs across the mouth of the tube, or small lizards and frogs at the bottom, waiting patiently for prey.
Some of the best places to see pitcher plants in the area—they also bloom in October—are Tarkiln Bayou State Preserve, Weeks Bay National Estuarine Research Reserve, Splinter Hill Bog Preserve, and Blackwater State Forest.
by Carrie Stevenson | Apr 15, 2020
The sight and scent of a wild azalea blooming in the woods can stop you in your tracks! Photo credit: Carrie Stevenson, UF IFAS Extension
From a distance, native azaleas are easily mistaken for honeysuckle vines. With long, arching stamens, you might be tempted to relive your childhood, hoping to pull the pistil from the bottom and find a single drop of sweetness on the end. Instead, upon close observation you will encounter an equally pleasurable but distinctly different scent. The wild Rhododendron canescens, known variously as a mountain, piedmont, or honeysuckle azalea, can range in flower color from white to deep pink. In northwest Florida, you will find it on the edges of swamps, or as I did on the sunny fringes of wooded areas with rich, moist soil. It is in bloom right now (March), along with its cousins, the white-blooming swamp azalea (Rhododendron viscosum) and the brilliant orange Florida flame azalea (Rhododendron austrinum).
The delicate flower of a honeysuckle azalea attracts hummingbirds and butterflies in the spring. Photo credit: Carrie Stevenson, UF IFAS Extension
Native azalea populations have declined due to wetland habitat loss, and their delightful smell and delicate flowers have made them susceptible to overcollection. Due to these factors, the Florida flame azalea is listed on the state endangered species list and wild azaleas should never be removed from their habitat. Native azalea species attract butterflies and hummingbirds, and are often planted in home landscapes as ornamental shrubs. Be sure you purchase them from reputable dealers that are not collecting from the wild.
by Carrie Stevenson | Apr 8, 2020
A biologist at Blackwater State Forest monitors endangered woodpecker habitat in a longleaf pine. Photo credit: Carrie Stevenson, UF IFAS Extension
In the Southeastern United States, our forests were once primarily longleaf pine-dominated ecoystems. Frequent summer thunderstorms and their accompanying lightning strikes would routinely set a portion of the forest afire. With plenty of space to move, wild animals relocated to safer portions of the forest or hunkered down in deep, winding gopher tortoise burrows underground. The longleaf pine’s life cycle has co-evolved with fire in such a way that its young growth stage is resistant to fire, and its success as a species requires fire to open up the canopy.
As human populations grew larger in the South, much of that forest land was harvested for timber, pitch, and turpentine, then cleared for agriculture and urban development. The American Southeast now has only 5% of that original longleaf pine forest. Thankfully, continued efforts led by organizations like the Longleaf Alliance and The Nature Conservancy have reminded folks of the species’ importance, and led to conservation and restoration efforts.
University of Florida Extension Agent surveys a planted forest with a producer in Washington County. UF/IFAS Photo: Josh Wickham.
Now, we have a newer mix of forest cover, with specimen trees preserved in parks and yards. In addition, we also have sustainable tree farms. You may have passed a wooded area where you noticed pine trees (mostly loblolly and slash in the south) were in perfect rows—these are being farmed, planted in rows just like any other crops. While they will be harvested eventually, during their lifetimes these trees fulfill all the roles we appreciate in wild forests–animal habitat, oxygen production, carbon dioxide uptake, and cooling via transpiration. The other positive of sustainable forestry is that almost as soon as they’re cut, they’re replaced. Trees are grown in a stepwise fashion to ensure there is always an available harvest. Multiple generations are grown at once to ensure there is rarely a truly bare spot in the landscape.
With 17 million acres in production, forestry makes up the largest agricultural commodity in Florida. When managing, planting, and harvesting trees, modern foresters take tree physiology, invasive species, disease outbreaks, and genetics into serious consideration. These professionals help produce necessary items for life; wood for construction, furniture, books, and the all-important toilet paper, which has emerged as a bartering item in the time of COVID-19. For more information on forestry in Florida, visit the University of Florida’s School of Forest Resources and Conservation.
