Description:
Claw vine (Macfadyena unguis-cati) Weed.
Macfadyena unguis-cati is a perennial, climbing liana found in tropical forests. Its dark, fibrous stem may exceed a diameter of 8cm and may extend higher than 20m into the tree canopy. The species’ long primary root extends across the soil surface making large tubers (up to 40cm long) every 50cm from which runners are produced. Additionally, the stem produces adventitious roots to anchor to the host tree, and often roots at the nodes.
The dark green, compound leaves are oppositely arranged and are composed of two leaflets with a trifid tendril between. The leaflet size and shape are variable: the small, narrowly ovate to lanceolate young leaves are 1-2cm long and 4-8mm wide and may become ovate, truncate, and up to 16cm long and 6.9cm wide at maturity. Mature leaves are glabrous with 4-6 prominent secondary veins. The hooked tendril, used to climb host trees, has three stiff arms 0.3-1.7cm long on a petiolule 0.5-2.5cm long.
M. Unguis-cati generally flowers from March-June in the late dry to early wet season with all flowers blooming within a few days. The inflorescence of the species is an axillary panicle generally bearing1-3 tubular-campanulate flowers, though up to 15 flowers may be present. The five-lobed, yellow corolla has red-orange lines in the throat and is 4.5-10cm long and 1.2-2.4cm wide. Stamens number four (occasionally five) and are about 3mm long. The species produces black, linear, flattened capsules ranging from 26-95cm long and 1-1.9cm wide. Each capsule contains about 100-200 small, brown, winged seeds that are 1-1.8cm long and 4.2-5.8cm wide.
Occurs in:
Natural forests, planted forests, range/grasslands, ruderal/disturbed, urban areas.
Habitat description:
The native habitat of Macfadyena unguis-cati is tropical dry forest, tropical and premontane moist forest, and occasionally wet forest. The species is present from sea level to over 600 metres in elevation in its native Puerto Rico, where it inhabits areas with 750-2400mm of rain annually. However, as an invasive species, M. unguis-cati may be found in orchards and gardens, on roadsides and in grasslands, and in open urban spaces, especially in temperate to subtopical regions with medium to high rainfall.
Claw vine (Macfadyena unguis-cati) Distribution in North America shown in green.
M. unguis-cati prefers fertile, well-drained soils but can survive in most soils except those which are salty or poorly drained. The species is very tolerant of low-light situations, especially when young, but grows much more vigorously in open, sunny habitat. It may be found anywhere from the forest floor to the top of the forest canopy.
General impacts:
Macfadyena unguis-cati is said to be one of the most destructive exotic vines and is considered to be a “troublesome”, “obnoxious”, and “serious” weed in much of its range. It is sometimes called a “transformer species” due to the way it leads to ecosystem change. M. unguis-cati effects all layers of infected forest ecosystems by spreading both vertically and horizontally across everything with which it makes contact. It forms a thick carpet of leaves and stems on the forest floor, outcompeting the understory plants and stopping germination of other species. It grows to top of the forest and spreads across the canopy, killing the host trees with its weight and shade.
M. unguis-cati grows rapidly, has a long lifespan, and requires few resources to thrive. It can survive grazing, fire, and light frosts; disturbances may actually make the species grow even more rapidly through new sprouting from damaged stems and roots. This species is difficult to eliminate due to its rapid growth, extensive root system, and prolific seed production. These factors combine to give the species a high risk score of 17.
Management information:
There are multiple methods of managing/eradicating Macfadyena unguis-cati including manual, chemical, and biological.
Manual: Manual control of M. unguis-cati is conducted by cutting the stems and digging out the roots of the invaders. This method is not practical except on very small
Close up of the Claw vine (Macfadyena unguis-cati) Weed.
populations because of the growth pattern of the species.
Chemical: Chemical control has been shown to be successful in areas in which the herbicide Glyphosate (N-(phosphonomethyl) glycine) has been approved. In these areas, vines are cut from trees at 1.5 metres and cut again at the surface. The cut stump is treated with a 1:1.5 Glyphosate:water treatement, or with straight Glyphosate. Once the area begins to actively grow following this treatment (usually three to six weeks later), the area is foliar sprayed with a Glyphosate and surfactant mix, with care being taken to avoid non-target species. Additional foliar spraying may be needed for five years or more after the initial treatment. This method should not be used in ecologically sensitive areas due to the potential herbicide drift.
Biological: The leaf-feeding beetle Charidotis auroguttata (Boheman), the leaf-sucking tingid Carvalhotingis visenda (Boheman), and the leaf-tying moth Hypocosmia pyrochroma (Jones) were all shown to be specific to M. unguis-cati. C. auroguttata was released in South Africa in 1999 to control its M. unguis-cati population, and C. visenda was approved in 2007 for release into Australia. Each biological agent works against M. unguis-cati by feeding on it preferentially to other tested species. The suitability of these biological agents to other environments must be carefully considered, and is dependant on the plant species present in each location, among other factors.
Cultural: Other tips for controlling the spread of M. unguis-cati include planting the species only in approved regions and pruning the planted species each year after flowering to prevent its spread
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