Southern
Research Station

Pitcher Plant Seed Research

Pitcher Plant Research

They grow in bogs and in wet longleaf pine savannahs. The plants are carnivorous, trapping insects in hollow, water-filled tubes that contain digestive enzymes. One species of interest, white-topped pitcher plant, produces flowers often referred to as “blood-cups” because of their shape and deep red color. Conservation and restoration efforts require further study of Sarracenia seed biology and ecology.

Sarracenia are threatened by wetland draining, invasive species, fire restriction, and illegal harvesting. Conservation and restoration efforts are underway in many states but little is known about Sarracenia seed biology and ecology.

Producing New Plants

White-topped pitcher plants have underground stems, called rhizomes. New plants can originate at buds along this stem; all will be genetically identical to the parent plant.

The plants also flower and produce genetically diverse individuals. In southern Alabama, white-topped pitcher plant seed pods ripen throughout the summer and mature in August, producing from a few hundred to thousands of 1-2 mm long, light-brown seeds from which new plants can grow.

A soil seed bank develops from the accumulation of viable ungerminated seeds in the soil. Seed banks play an important role in the establishment and regeneration of terrestrial plant communities. Composition of a soil seed bank can affect the successful continuance of an existing plant association. If seeds have short life spans, mature flowering plants must be on-site to replenish the supply of seeds in the seed bank. If seeds survive for a few decades, regeneration can occur even if the mature plants do not flower every year or are extirpated from the site.

Research Studies

Seed bank studies have been established to determine how long the seeds of various species of plants remain in the soil seed bank. In addition to white-topped pitcher plant, studies have been initiated for pineland nerveray , ramp, black cohosh, and blue cohosh. For these experiments, seeds are sewn into fine-mesh bags which are then buried in the field or, in the case of white-topped pitcher plant, in an artificially created “wetland”. Bags are harvested at intervals for at least 2 years to determine seed viability. Results to date show that white topped pitcher plant seeds rapidly deteriorate in the seed bank, with just 2% of the seeds remaining viable after 1 year. Such limited length of survival in the seed bank for any species emphasizes the importance of conserving existing flowering populations.

References

• Connor KF, Gibbs H. Germination and field survival of white-topped pitcher plant seeds. 2012. In: Kush, J.S., comp. Proceedings of the Eighth Longleaf Alliance Regional Conference. Longleaf Alliance Report No. 16: 42-46.