Sarracenia purpurea

       April Sanders

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The commonly known, pitcher plant, is known for its carnivorous feeding.  This herbaceous dicot is a perennial that forms leaves that resemble a pitcher, or a container that holds liquid.  The juvenile leaves can be red, but usually turn green and the veins become bright red as they age.  The insides of the leaves are lined with small downward-pointing hairs used to trap insects.  They can grow one to six inches in height and their single, leafless flower stalks can grow up to two feet.  The flower is large (5-6 cm wide) with 5 dark red-purple petals that curve inward over the style.

Distribution

This species is native to Michigan wetlands and is also found all over the eastern United States and parts of California.  See distrubution map below.  

State Distributional Map for SAPU4

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Natural History:

 

a. Habitat Requirements

S. purpurea is normally found in ombrotrophic, or nutrient poor, Sphagnum bogs and floating bog mats; although, it is occasionally found in calcium rich environments.  It has also been noted that it prefers well-lit areas, as opposed to shady conditions, where it can receive the maximum amount of sunlight.  

b. Nutrition

The pitcher plant gets most of its nutrition from insects that become trapped in their cupped leaves (see below).  Insects are attracted to the scent of the leaves and the nectar that is contained the rainwater filled pitchers.  The insects enter the pitcher and find themselves trapped by the downward-facing hairs that line the inside of the leaves.  Eventually, the insect drowns and the plant releases enzymes that break down the organism into nitrogenous compounds and other nutrients that the plant needs to survive.  In a lifetime, pitchers on average catch 11mg, in dry mass, of animal biomass and the larger pitchers catch more than the smaller ones do (Heard, 1998).

Click on this Photograph of Sarracenia purpurea to enlarge it and download  a high-resolution JPEG file

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c. Interactions

The carnivorous plant’s interactions with other organisms normally occur during feeding.  The plant is known to feed primarily on mosquitoes, ants, and some flies.  Interestingly, the pitchers have a symbiotic relationship with some anaerobic bacteria.  These bacteria live in the rainwater that is contained the pitcher itself and aid the enzymes in decomposing the animal material.

d. Reproduction

The pitcher plant has a single flower inflorescence that grows up to 24” in height and blooms between May and July (see below).  In late fall, 500-1500 5 chambered capsules are dispersed, normally, less than a foot from the mother plant.  This is the reason why the species are isolated to bog environments.  Only rare, long-distant transport has spread the plant throughout the eastern United States (Ellison & Parker, 2002). 

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Human Interest

Besides the plants’ fascinating carnivorous nature, the pitcher plant has been found to have many medicinal uses.  For example, it can cure small pox, it is used as a laxative, and it also aids in easing stomach ailments. 

Ecology Issues

The pitcher is an obligate wetland indicator, meaning that it almost always occurs in a natural bog environment. Another main interest, which is relatively new to the plants uses, is the fact that it can be used as a nitrogen indicator.  A study was performed where the plants were fertilized with nitrogen and their growth was observed.  The primary production in pitchers was dramatically reduced; therefore, indicating nitrogen accumulation in soils (Ellison & Gotelli, 2002).  In other words, the more nitrogen that accumulates in the soil, the more stunted the plants growth will be, above and below the soil.  Although the pitcher plant is relatively abundant in number, it is a threatened species.  The circumstance is worse in Georgia where the plant is considered an endangered species.

References

Chadde S. 2002. A Great Lakes Wetland Flora – A Complete, Illustrated Guide to the Aquatic and Wetland Plants of the Upper Midwest. PocketFlora Press, Calumet, Mi. 648 p.

Ellison AM, Gotelli NJ. Nitrogen availability alters the expression of carnivory in the northern pitcher plant, Sarracenia purpurea L. Proceedings of the National Academy of Sciences of the United States of America. 99(7):4409-5512.2002.

Ellison AM, Parker JN.  Seed dispersal and seedling establishment of S. pururea (Sarracenaceae). American Journal of Botany. 89(6):1024-1026.2002.

Greive M. A Modern Herbal. 2003. Online. 20 November 2003. www.botanical.com

Heard SB. Capture rates of invertebrate prey by the pitcher plant, S. purpurea L. American Midland Naturalist. 139(1):79-89.1998.

“pitcher plant.” Columbia Encyclopedia, Sixth Edition, 2003. Online. 20 November 2003. www.ecyclopedia.com

                          USDA Plants Database. Online 16 November 2003.  www.plants.usda.gov