July 2007. Vanuatu asked if members could identify a weed that a farmer is Solomon Islands was said to be using as a ground cover for vanilla with good results. Members identified the weed as Tradescantia sp. There are sveral species and they are all invasive. The GISD (Global Invasive Species Database) has profiles on two Tradecantia species: T fluminensis: http://www.issg.org/database/species/ecology.asp?si=497&fr=1&sts=sss and T spathacea:

http://www.issg.org/database/species/ecology.asp?si=493&fr=1&sts=sss.

Another contribution suggested that the plant was Callisia repens. There is information on this plant at:

www.hear.org/starr/hiplants/images/thumbnails/html/callisia_repens.htm
www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl

And pictures:

http://davesgarden.com/pf/go/2566/
http://onaleeseeds.bizhosting.com/bolivian_jew_turtle_vine_itsy_bitsy_inch_vine_callisia_repens_green_purple_leaf.html

The leaves look a little too rounded for the Tradescantia and Commelina species.