What Pollinates Night-Blooming Cereus?

Flowers

• The four species referred to as night blooming cereus all produce a creamy-white flower with a 6-inch diameter and a heavy fragrant scent. The flower, which has many petals, sits on top of a long tube. Peniocereus greggii and Selenicereus grandiflorus have slender thorns; the other two species are thornless. Cereus flowers start opening just after dark, and may not be fully open until midnight. An hour or two after the sun rises, the flower is dead.

Moths

• Sphinx moths, or hawk moths, are also known as hummingbird moths because their wings beat so quickly that they make a humming sound, and they are able to hover in midair for long periods, like hummingbirds do. Sphinx moths are medium to large sized moths with a wingspan of up to 6 inches, depending on the species. Their front wings are narrow and shaped like a triangle, and each moth can extend its proboscis, which is the hollow tube they use to suck nectar, for several inches, making it easy to reach the nectar inside the cereus flower. Sphinx moths are the adult form of hornworm caterpillars, which are major pests of plants like tomatoes, potatoes and tobacco.

Bats

• Nectar-feeding bats like the lesser long-nosed bat migrate a thousand miles or more from Mexico to Arizona, every spring, where they help pollinate night-blooming cereus flowers by feeding on their nectar. The lesser long-nosed bat is a yellowish-brown or gray bat with a rusty brown-colored belly. It has small ears and a triangular-shaped structure on the end of its nose, known as a noseleaf. Scientists believe that noseleafs are used to help bats focus echolocation calls.

Threats

• Night-blooming cereus flowers require cross-pollination because they aren't able to fertilize themselves. However, the plants are spread over a wide area, so pollinators have to fly hundreds of yards between them. Because people use a lot of pesticides in the area where these plants grow, the hawkmoth population has been drastically reduced, leaving many flowers unable to bear fruit. The problem is made worse by the fact that the lesser long-nosed bat, and other bats that pollinate night-blooming cereus, are federally endangered species. A final threat comes from the plants themselves. Because the night-blooming cereus is a popular plant that has medicinal and ornamental value, it has been overcollected and, in some areas, is now listed as an endangered species as well.