bignonioides

Southern Catalpa

Indian Bean , Fish Bait Tree

The Southern Catalpa (Catalpa bignonioides) is a handsome, tree native to just a few southern states of the USA: , , and . In Australia, Catalpa in late October through to December, producing large clusters of white flowers, each petal with purple spots and bright orange yellow stripes. Do the flowers look familiar? They should, as Catalpa belongs to the same family () as Jacaranda which produces masses of heavenly blue-mauve flowers at the same time of year. The Bignoniaceae is a large family, ~ 700 , almost cosmopolitan, mostly tropical, and with its centre of diversity in the northern regions of South America1,2.

There are two species of Catalpa native to North America, C. bignonioides and C. speciosa which comes from more northerly states of the USA. Other species are scattered across the Caribbean, Japan and East Asia. Catalpa takes its name from Catawba, the name used by the Catawba Native Americans for whom the tree is the tribal totem1.

The Southern Catalpa has large, light, bright green, heart-shaped which have a curious adaptation: (fructose, glucose and sucrose) is secreted from clusters of tiny glands in the axils of the primary veins! What for? Well, this is where it gets really interesting. When larvae of the Sphinx moth, Ceratomia catalpa attack the leaves of Catalpa, within 36 hours, nectar production increases massively, in the process attracting ant ‘bodyguards’. The tree eventually has two lines of defense: the number of ants (bodyguards) increases after an attack by moth larvae and the increased workforce concentrates their efforts on protecting leaves that have been attacked3!!

The Catalpa may try to repel these Lepidopterous invaders but Professor Kim D. Coder of the Warnell School of Forest Resources describes the Catalpa not just as a popular shade tree in the United States but also desirable because Nectar produced from minute glands in leaves of Catalpa bignonioides: J.S. Peterson the leaf eating larvae of the Catalpa @ USDA-NRCS Database Sphinx Moth are prized by fishermen in the southern states. In his words: ‘Many people dream of selling catalpa moth larvae to fishing enthusiasts. Unfortunately, the risks associated with tree culture and moth culture can be immense. Most people settle for a few trees which dependably serve a single family. represent a Southern tradition at many levels. a piece of cultural history--the Southern catalpa.4’

1Wikipedia: http://en.wikipedia.org/wiki/Bignoniaceae 2Wikipedia: http://en.wikipedia.org/wiki/Catalpa_bignonioides 3 J. H. Ness 2003 Catalpa bignonioides alters extrafloral nectar production after herbivory and attracts ant bodyguards Oecologia 134: 210-218. 4K. D. Coder, Warnell School of Forest Resources: http://warnell.forestry.uga.edu/service/library/index.php3?docID=178&docHistory[]=2 Map modified from United States Geological Service: http://esp.cr.usgs.gov/data/little/catabign.pdf

Alison Downing, Kevin Downing & Brian Atwell, Department of Biological Sciences 11th November 2013