Calico flower (Aristolochia elegans)

Overview:

Aristolochia littoralis, native to Brazil, is an ornamental vine cultivated in Hawai’i and other tropical areas for their colorful and unique pipe shaped flowers. A. littoralis is known to spread from initial plantings in several places where it is cultivated, including Hawai’i, Florida, South Africa, and other Pacific Islands. In Hawai’i, A. littoralis is naturalized on Kaua’i, O’ahu, and Maui. On Maui, A. littoralis is currently sparingly cultivated and was only recently documented as naturalized from a lowland site near Kipahulu. A. littoralis produces dehiscent capsules with numerous wind born seeds that readily germinate nearby plantings. Plants do spread from initial plantings, but it is uncertain if it will become a serious concern to natural areas or simply a secondary weed of lowland disturbed areas.

Description:

Vigorous lianas. Leaves green on upper surface, lower surface glaucous, cordatereniform, 7-9 cm long, 6-10 cm wide, pseudostipules auriculate, amplexicaul. Flowers solitary in the leaf axils, greenish yellow and dark blackish purple, the tube bent, ca. 3 cm long, the limb unlobed, disk-shaped, ca. 10 cm in diameter, abruptly spreading from the tube; gynostemium 8 mm high, 5 mm wide. Capsules cylindrical, 4.5 cm long, 2.5 cm in dimeter. Seeds flat, ca. 6 mm long.

Biology and ecology:

Cultivation:

A. littoralis vines are widely cultivated in tropical areas throughout the world. They are vigorous growers and are usually planted for shade, screening, and for their unusual. The vines are heavy and require strong support. It is also reported to have medicinal qualities. On Maui, A. littoralis is not very common and is occasionally planted in a few lowland sites.

Invasiveness:

These aggressive woody climbers are known to escape cultivation in at least Florida, Hawai’i, South Africa, and elsewhere in the Pacific. Invading non-native lianas have the potential to over-run desirable vegetation, weigh them down, and create openings for further invasion. On Maui, A. littoralis, with numerous flat wind dispersed seeds born in a dehiscent capsule, readily germinates in places where it is cultivated. Numerous seedlings are found at several lowland sites on Maui, including Kipahulu, Waikapu, and Lahaina. A. littoralis has a similar habit, vigor, and appearance to that of Coccinia grandis, a Hawai’i state noxious weed currently being targeted for eradication on Maui by the Maui Invasive Species Committee and the Department of Agriculture. Like C. grandis, this vine would most likely be hard to control once established, due to numerous above and under ground stems and roots that require numerous herbicide applications in order to achieve complete control.

Control Methods:

There was not much documentation found on control of this species. Perhaps methods employed to control ivy gourd (Coccinia grandis), a similar looking vine, would be useful to control this species.

Mechanical control: It may be possible to pull up small seedlings. With other vines, such as C. grandis, cutting at the base without chemical treatment is usually not successful and actually makes control more difficult.

Chemical control: The preferred method of control for a similar vine, Coccinia grandis, is to leave the vines in place and use a basal bark application by applying Garlon 4 (triclopyr) at 100% to the base of the vine, as close to the root as possible. To allow proper translocation, do not cut vines. Repeat control is necessary to control any regrowth or stems that were originally missed.

Biological control: There are no known biological control programs for A. littoralis.

Cultural control: The public could be informed not to plant A. littoralis or other weedy vines that readily escape from gardens.

Noxious weed acts: In north and central Florida, Aristolochia littoralis is considered a category II invasive plant species by the Florida Exotic Pest Plant Council. Category II is defined as, invasive exotics that have increased in abundance or frequency but have not yet altered Florida plant communities to the extent shown by category I. In the Skukuza staff village of the Kruger National Park, South Africa, A. littoralis (as A. elegans) was listed as a priority 1 non-native plant slated for removal.