Luffa - Luffa cylindrica

A vigorous annual vine. Young fruits are used as squash substitute, mature fruits are dried and used as a bathroom sponge.
Sow in spring.
Suitable for temperate, subtropical and tropical areas. [from Greenharvest.com.au]

Different from ANGLED LUFFA (Luffa acutangula) syn. Okra Vine, Okra Cee Gwa

The bright yellow flower of the Luffa vine

Immature Luffa fruit

Mature Luffa Fruit

There seem to be two different schools of thought on the processing of these mature fruits to obtain the vegetable sponge. Rhonda-Jean's method (see Down to Earth Links below) involves leaving the fruit on the vine to dry. While other information online recommends the removal of the fruit to encourage further fruiting and allowing it to either dry or processing the fruit 'as is'.
It would appear however that the processing is easier and less messy when the fruit is fully dried :-)

Links for further information

Gardening Australia
http://www.abc.net.au/gardening/stories/s1599776.htm

Some excellent information from my favourite blogger Rhonda-Jean at Down to Earth. Wonderful photos and detailed information.

Growing Luffas
http://down---to---earth.blogspot.com/2009/02/growing-luffas-loofahs.html

Harvesting Luffas
http://down---to---earth.blogspot.com/2007/06/harvesting-loofahs.html

Processing Luffas
http://down---to---earth.blogspot.com/2009/03/processing-luffas-loofahs....