Uchan, known scientifically as Dioscorea bulbifera, is commonly referred to as air potato due to its distinctive aerial tubers. This plant exhibits a dual nature, serving as a cultivated food source in some parts of the world while simultaneously being a highly invasive species in other regions. Understanding this plant involves recognizing both its traditional uses and its ecological impact.
Understanding Uchan
Dioscorea bulbifera, also known as air yam or bitter yam, is a member of the yam family (Dioscoreaceae). This perennial, climbing vine is native to tropical Africa, Asia, and northern Australia. It has become widely naturalized in many other tropical and subtropical regions globally, including the southeastern United States and various Pacific islands.
The plant is characterized by broad, heart-shaped leaves arranged alternately along its twining stems, which can extend 10 to over 20 meters. A defining feature is the production of aerial tubers, or bulbils, that form in the leaf axils. These bulbils vary in size from small marbles to larger than a softball and play a primary role in the plant’s dispersal and reproduction.
Cultivating and Using Uchan
In its native regions and cultivated areas, Dioscorea bulbifera has been traditionally used as a food source. The plant thrives in warm temperatures, ideally between 20 and 30°C, preferring moist but well-drained, sandy loamy soils. While it can tolerate various soil types, good drainage is necessary to prevent root rot.
Proper preparation is necessary due to toxic alkaloids present in many wild varieties. Aerial tubers must be thoroughly processed, often by boiling or leaching, to remove harmful compounds before consumption. Despite toxicity concerns, selected cultivars have been developed with lower toxin levels. Historically, Uchan has been used as a starchy food and in traditional medicine for various ailments, including conjunctivitis and diarrhea.
Uchan’s Invasive Nature
Dioscorea bulbifera is considered a highly invasive species in many parts of the world, particularly in subtropical and tropical environments like Florida, USA. Its aggressive growth rate, up to 20 centimeters (8 inches) per day, allows it to quickly overwhelm native flora. The plant forms dense mats of vines that climb high into tree canopies, shading out and displacing underlying vegetation.
This vine spreads extensively through its prolific production of aerial tubers and, to a lesser extent, underground tubers. When bulbils fall to the ground, they readily sprout new plants, making control challenging. The ecological impact includes reducing biodiversity, altering natural habitats, and disrupting ecosystem functions by competing with native species for light and resources.
Controlling and Managing Uchan
Managing invasive Dioscorea bulbifera requires persistent, integrated approaches. For smaller infestations, manual removal is effective, involving cutting vines, collecting fallen bulbils, and digging up underground tubers. Proper disposal of all plant material, such as by incineration or landfill, is crucial to prevent further spread.
Biological control methods show promise, with the introduction of the air potato leaf beetle (Lilioceris cheni) from Asia. This beetle feeds on Dioscorea bulbifera leaves, reducing plant vigor and bulbil production. A newer biological control agent, Lilioceris egena, targets bulbils directly, complementing Lilioceris cheni’s efforts. For larger infestations, chemical control using herbicides like glyphosate or triclopyr can be applied to foliage or cut stems. Multiple applications may be necessary, with timing important during active growth.