The Mysterious Moonflower (Ipomoea alba)

The lush vine twines upward on the fence and as it goes produces large flower buds. These sit there, green and still, waiting for darkness to arrive. Well after the sun goes down one or two buds begin to stir ever so slightly. Then, in less than a minute, a four to six inch flower, pure white, opens to welcome the pollinators of the night. When the first rays of morning begin to lighten the sky, the edges of the flower droop in a kind of flaccid slide, and by full light the flower is a wilted shadow of its former self.
This is the cycle of the Moonflower, a kind of Morning Glory. Night bloomers are really special flowers. They take advantage of all the light of the day to grow but don’t compete for the daytime pollinators. Instead they attract night moths such as the hawkmoth.
I love a mystery, and in looking around for information on this beauty I found a confusing array of both common and Latin names. Numerous Moonflowers are out there. Mine turned out to be currently and probably definitely named Ipomoea alba . But take a look at the synonyms I found:

Synonym:Calonyction album

Synonym:Calonyction aculeatum

Synonym:Calonyction bona-nox

Synonym:Ipomoea noctiflora

Synonym:Calonyction pulcherrimum

This is the kind of thing that gives people headaches. What is it really called? Why the confusion of names? Where is a definitive source for this pretty puzzle? In addition to a mystery I love to ferret around looking for odd things, and this expedition turned out to be easier than I though. The USDA has a plant taxonomy (names and classification) data base called GRIN which stands for Germplasm Resources Information Network. Using DNA analysis and a classification method called Cladistics, the exact relationships of one living thing to another can be assessed. Voila! The statement below is the definitive position of my mysterious plant:

“Though formerly classified as genus Calonyction, species aculeatum, it is now properly assigned to genus Ipomoea, subgenus Quamoclit, section Calonyction.” (1) and my species is alba .

A beauty by any name is still a beauty, and this is one for sure. And, as a bonus, as are most moth pollinated flowers, it is wonderfully fragrant.

1. http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?20135