by Sheila Dunning | Mar 1, 2018
An invasive plant is defined as a plant that is non-native to the ecosystem under consideration and whose introduction causes or is likely to cause economic or environmental harm or harm to human health (National Invasive Species Council, 2001). Research supports the fact that invasive plants damage natural areas, but there is great debate over which plants are invasive and where they are causing problems. Many lists of invasive plants have been complied by government agencies or environmental groups such as the Florida Exotic Pest Plant Council (www.fleepc.org) that include plants currently available at nurseries. Examples of such plants are Mexican petunia, Lantana and Porterweed.
Mexican Petunia
The bright color and rapid growth of Mexican petunia (Ruellia tweediana or R. brittoniana) has resulted in mass plantings that disrupt native wetland systems. The species is not used by butterflies, contrary to published misinformation. On the other hand, Porterweed is attractive to butterflies and the deep blue flower color of Stachytarpheta urticifolia has proven to be equally popular with gardeners. Additionally, Lantana camara is a favorite of Lepidoptera and a prolific bloomer, so hundreds of plants are installed in the landscape annually, spreading viable seed throughout the neighborhood and woods. Unfortunately, when it is found in natural areas it is difficult to distinguish the native lantana (L. depressa) from the invasive lantana (L. camara) and the two species can hybridize, making accurate identification even harder.
In fact, all three plants have native cousins with acceptable growth habits. Drought tolerant Ruellia caroliniensis has a pale violet-colored flower that serves as a host plant to the Buckeye butterfly. Stachytarpheta urticifolia is a low-growing groundcover with pale blue flowers. If the Porterweed is growing tall and upright, it is not the native. Leaf characteristics can be used to distinguish the native lantana (L. depressa) from the invasive lantana (L. camara). Native lantana has a tapered leaf base, whereas the invasive lantana has a truncate leaf base.
Lantana camara
Cultivars of species may have characteristics making them less invasive (Wood, 2007). University of Florida faculty has implemented an assessment process to evaluate non-native, highly utilized plants that are invading natural areas in Florida, including the marketed cultivars. The “UF-IFAS Assessment of Non-Native Plants in Florida’s Natural Areas” (IFAS Assessment) uses four criteria to categorize many of the plants available in the nursery trade. Over 700 species have been assessed (results are available at http://plants.ifas.ufl.edu/assessment/).
Some of the latest research included Lantana, Ruellia, and Stachytarpheta species. Each of them yielded a sterile cultivar that exhibited both the desired flowering of the invasive species while posing no threat to natural areas. When evaluated, these three cultivars scored well for minimal ecological impact, potential for expanded distribution, management difficulty and yet have a good economic value for the industry. So when looking for this year’s new garden introduction, one should consider ‘Purple Showers’ Ruellia, ‘Violacea’ Porterweed or ‘Patriot Cowboy’ Lantana. According to Dr. Gary Knox (UF/IFAS, North Florida Research and Education Center, Quincy, FL), they behaved well in the UF-IFAS assessment.
by Sheila Dunning | Jan 19, 2018
The Florida Master Naturalist Program is an adult education University of Florida/IFAS Extension program. Training will benefit persons interested in learning more about Florida’s environment or wishing to increase their knowledge for use in education programs as volunteers, employees, ecotourism guides, and others.
Through classroom, field trip, and practical experience, each module provides instruction on the general ecology, habitats, vegetation types, wildlife, and conservation issues of Coastal, Freshwater and Upland systems. Additional special topics focus on Conservation Science, Environmental Interpretation, Habitat Evaluation, Wildlife Monitoring and Coastal Restoration. For more information go to: http://www.masternaturalist.ifas.ufl.edu/ Okaloosa and Walton Counties will be offering Upland Systems on Thursdays from February 15- March 22. Topics discussed include Hardwood Forests, Pinelands, Scrub, Dry Prairie, Rangelands and Urban Green Spaces. The program also addresses society’s role in uplands, develops naturalist interpretation skills, and discusses environmental ethics. Check the website for a Course Offering near you :http://conference.ifas.ufl.edu/fmnp/
by Sheila Dunning | Jan 19, 2018
We plant trees with the intention of them being there long after we are gone. However, many trees and shrubs fail before ever reaching maturity. Often this is due to improper installation and establishment. Research has shown that there are techniques to improve survivability. Before digging the hole:
- Look up. If there is a wire, security light, or building nearby that could interfere with proper development as it grows, plant elsewhere.
- Dig a shallow planting hole as wide as possible. Shallow is better than deep! Many people plant trees too deep. A hole about one-and-one-half the diameter of the width of the root ball is recommended. Wider holes should be used for compacted soil and wet sites. In most instances, the depth of the hole should be LESS than the height of the root ball, especially in compacted or wet soil. If the hole was inadvertently dug too deep, add soil and compact it firmly with your foot. .
- Find the point where the top-most root emerges from the trunk. If this is buried in the root ball then remove enough soil from the top so the point where the top-most root emerges from the trunk is at the surface. Burlap on top of the ball may have to be removed to locate the top root.
- Slide the plant carefully into the planting hole. To avoid damage when setting a large tree in the hole, lift the tree with straps or rope around the root ball, not by the trunk. Special strapping mechanisms need to be constructed to carefully lift trees out of large containers.
- Position the plant where the top-most root emerges from the trunk slightly above the landscape soil surface. It is better to plant a little high than to plant it too deep. Remove most of the soil and roots from on top of the root flare and any growing around the trunk or circling the root ball. Once the root flare is at the appropriate depth, pack soil around the root ball to stabilize it. Soil amendments are usually of no benefit. The soil removed from the hole and from on top of the root ball makes the best backfill unless the soil is terrible or contaminated. Insert a square-tipped balling shovel into the root ball tangent to the trunk to remove the entire outside periphery. This removes all circling and descending roots on the outside edge of the root ball.
- Straighten the plant in the hole. Before you begin backfilling have someone view the plant from two directions perpendicular to each other to confirm that it is straight. Break up compacted soil in a large area around the plant provides the newly emerging roots room to expand into loose soil. This will hasten root growth translating into quicker establishment Fill in with some more backfill soil to secure the plant in the upright position.
- Remove synthetic materials from around trunk and root ball. Synthetic burlap needs to be completely removed from the root ball; treated burlap can be left in place. String, strapping, plastic, and other materials that will not decompose and must be removed from the trunk at planting. Remove the wire above the soil surface from wire baskets before backfilling.
- Apply a 3-inch-layer of mulch. To retain moisture and suppress weeds cover the outer half of the root ball with an organic mulch. Do not cover the stem of the plant or the connecting root flare.
- Water consistently until established. For nursery stock less than 2-inches in caliper, this will require every other day for 2 months, followed by weekly 3-4 months. At each irrigation, apply 2 to 3 gallons of water per inch trunk caliper directly over the root ball. Never add irrigation if the ground is saturated.
by Sheila Dunning | Dec 15, 2017
According to Druid lore, hanging the plant in homes would bring good luck and protection. Holly was considered sacred because it remained green and strong with brightly colored red berries no matter how harsh the winter. Most other plants would wilt and die.
Later, Christians adopted the holly tradition from Druid practices and developed symbolism to reflect Christian beliefs. Today, the red berries are said to represent the blood that Jesus shed on the cross when he was crucified. Additionally, the pointed leaves of the holly symbolize the crown of thorns Jesus wore on his head.
Several hollies are native to Florida. Many more are cultivated varieties commonly used as landscape plants. Hollies (Ilex spp.) are generally low maintenance plants that come in a diversity of sizes, forms and textures, ranging from large trees to dwarf shrubs.
The berries provide a valuable winter food source for migratory birds. However, the berries only form on female plants. Hollies are dioecious plants, meaning male and female flowers are located on separate plants. Both male and female hollies produce small white blooms in the spring. Bees are the primary pollinators, carrying pollen from the male hollies 1.5 to 2 miles, so it is not necessary to have a male plant in the same landscape.
Several male hollies are grown for their compact formal shape and interesting new foliage color. Dwarf Yaupon Hollies (Ilex vomitoria ‘Shillings’ and ‘Bordeaux’) form symmetrical spheres without extensive pruning. ‘Bordeaux’ Yaupon has maroon-colored new growth. Neither cultivar has berries.
Hollies prefer to grow in partial shade but will do well in full sun if provided adequate irrigation. Most species prefer well-drained, slightly acidic soils. However, Dahoon holly (Ilex cassine) and Gallberry (Ilex glabra) naturally occurs in wetland areas and can be planted on wetter sites.
Evergreen trees retain leaves throughout the year and provide wind protection. The choice of one type of holly or another will largely depend on prevailing environmental conditions and windbreak purposes. If, for example, winds associated with storms or natural climatic variability occur in winter, then a larger leaved plant might be required.
The natives are likely to be better adapted to local climate, soil, pest and disease conditions and over a broader range of conditions. Nevertheless, non-natives may be desirable for many attributes such as height, growth rate and texture but should not reproduce and spread beyond the area planted or they may become problematic because of invasiveness.
There is increasing awareness of invasiveness, i.e., the potential for an introduced species to establish itself or become “naturalized” in an ecological community and even become a dominant plant that replaces native species. Tree and shrub species can become invasive if they aggressively proliferate beyond the windbreak. At first glance, Brazilian pepper (Schinus terebinthifolius), a fast-growing, non-native shrub that has a dense crown, might be considered an appropriate red berry producing species. However, it readily spreads seed disbursed by birds and has invaded many natural ecosystems. Therefore, the Florida Department of Environmental Protection has declared it illegal to plant this tree in Florida without a special permit. Consult the Florida Exotic Pest Plant Council’s Web page (www.fleppc.org) for a list of prohibited species in Florida.
For a more comprehensive list of holly varieties and their individual growth habits refer to ENH42 Hollies at a Glance: http://edis.ifas.ufl.edu/mg021
by Sheila Dunning | Nov 3, 2017
Since we are approaching the peak dates in mid-October, it is time to get your gardens ready for migrating monarchs to fuel up on nectar sources. In their Mexican overwintering sites, these monarchs will have to survive on stored fat all winter. So they need to build up fat reserves by feeding on flowering plants along their migration route. Saltbush, Goldenrod, Narrowleaf Sunflower, Blanketflower and Milkweed are some of the nectar-rich blooms in the Florida Panhandle this time of year.
Monarchs begin leaving the northern US and Canada in mid-August. They usually fly for 4-6 hours during the day, coming down from the skies to feed in the afternoon and then find roosting sites for the night. Warmth and nectar enable butterflies to gain the energy needed to keep on flying. Monarchs cannot fly unless their flight muscles reach 55ºF. On a sunny day, they bask by extending their wings to allow the black scales on their bodies to absorb heat. But on a cloudy day, they generally don’t fly if it is below 60ºF.
These graceful insects capitalize on the warm air they encounter when they head south. Thermals are columns of rising air, caused by uneven heating of the earth. They form wherever the air is just a few degrees warmer than the air next to it. Thermals often form wherever large patches of dark ground are adjacent to lighter-colored ground, such as over parking lots, above farm fields, highways, and next to rivers and lakes. Monarchs are so light that they can easily be lifted by the rising air.
But they are not weightless. In order to stay in the air, they must move forward while also staying within the thermal. They do this by moving in a circle. At that point, the monarch glides forward in a south/southwesterly direction with the aid of the wind. It glides until it finds another thermal, and rides that column of rising air upwards again. Monarchs can glide forward 3-4 feet for every foot they drop in altitude. If they have favorable tail winds, monarchs can flap their wings once every 20-30 feet and still maintain altitude.
When winds are from the south, monarchs fly very low, often choosing to land and find cover or refuel on available nectar sources. They may wait for the winds to change direction, and as a result, can form large roosts as they accumulate in a protected location.
The average pace of the migration is around 20-30 miles per day. But tag recoveries have shown that monarchs can fly 150 miles or more in a single day if conditions are favorable. Monarchs migrate during the day, coming down at night to gather together in clusters in a protected area. In the south, they might choose oak or pecan trees, especially if the trees are overhanging a stream channel.
Monarchs migrate alone—they do not travel in flocks like birds do. So they often descend from the sky in the afternoon to feed, and then search for an appropriate roosting site. Most roosts last only 1 or 2 nights, but some may last a few weeks.
How do monarchs find their way to Mexico? We really don’t know for certain. We do know that monarchs have a sun compass in their brain, and a circadian clock in their antennae. The clock and compass are integrated in the brain to form a time-compensated sun compass. Using the sun and polarized light waves, monarchs can maintain a general S/SW heading throughout the day. Even with that, it is amazing that they can find the exact spot year after year.
