What flower moves when touched?
By Chelsie Vandaveer
August 14, 2002
killerPlants Tendrils: ~~1~~2~~3~~4~~5~~
Suggested Reading: Click here.
The bladderworts (Utricularia spp.) are a ubiquitous lot; there are an estimated 200 species of these carnivorous plants worldwide. The plants are seldom noticed except when in bloom then they may cover a shallow pond or muddy flat with white, yellow, or purple blooms. Bladderworts are best known for their tiny modified leaves which suck in unsuspecting prey.
The bladderwort leaf is pouch-shaped with a trapdoor and sensitive trigger 'hairs'. The leaf absorbs water from its interior creating a partial vacuum. When a water flea (Daphnia spp.) or mosquito larvae bungles by disturbing the triggers, the door opens, water and prey rush in. Donald Snell (Carnivorous Plants of the United States and Canada, 1976) wrote, "The speed of the trapping process has been estimated at 1/460 of a second...."
Bladderwort flowers have their own magic. The plants produce two types of flowers; cleistogamous (closed flowers) and chasmogamous (open flowers). Cleistogamous flowers never open, yet they self-pollinate and produce seed.
Chasmogamous flowers open, but have a personate (bulging) lip petal which can be negotiated only by insects strong enough to force their way into the flower. The lip petal also has a spur or nectary to reward the persistent insect.
The anthers lie toward the back of the flower above the nectary. While the bee drinks nectar, it brushes pollen on its head and back. This pollen will be carried to the next flower the bee visits for the open flower has a mechanism to prevent it from self-pollinating.
Like the traps, the stigma of the open flower is capable of motion. The stigma has a lobe. When a bee pushes into the flower and touches the stigma, it deposits any pollen it may have carried from a previous flower. The touch causes the lobe to snap over the stigma preventing it from receiving any more pollen, especially its own.
Plant of the Week 05/03/2004
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Floating bladderwort (Utricularia inflata)
The floating bladderwort is native to the eastern Atlantic states from New York and Massachusetts to Florida and westward from Tennessee to eastern Texas and southeastern Oklahoma. It is easily identified by the inflated branches that support the inflorescence. The inflorescence may bear up to 20 yellow flowers. (Utricularia radiata also has spoked supports, but it is a smaller plant with fewer (1 to 6) flowers.) Utricularia flowers have a mechanism, a closing stigmatic lobe that prevents self-pollination. Tiny seeds are borne inside a capsule. The seeds are small enough that a strong wind will disperse them to new locations.
Plant of the Week 05/03/2004
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The University of Florida, Center for Aquatic and Invasive Plants has a page on bladderworts (Utricularia spp.). To view the page, click on the link:
http://aquat1.ifas.ufl.edu/utripic.html
Click on the thumbnails to enlarge the images.
Microscopy UK has a wonderful page by Wim van Egmond about the water flea (Daphnia longispina). To view this tiny creature, click on the link:
http://www.microscopy-uk.org.uk/mag/artmar02/fleanatomy.html
Note: Bladderwort traps and water fleas are very similar in size and shape.
killerPlants Tendrils: ~~1~~2~~3~~4~~5~~
Suggested Reading:
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