Sarracenia, also known as the American pitcher plant, is a genus of temperate carnivorous plants comprising 8 to 11 species native to the sphagnum bogs and open wetlands of the eastern coast of the United States and Canada. The genus belongs to the family Sarraceniaceae, which also contains closely related carnivorous plants including Heliamphora and Darlingtonia. Today, Sarracenia are threatened in the wild due to poaching and habitat loss as a result of urban development.
At the conservatory, our collection of Sarracenia helps to educate students and visitors on their special adaptations. Sarracenia have evolved to catch insects by producing highly modified leaves or “pitchers” to catch and digest crawling and flying insects, to compensate for the lack of nitrogen and phosphorus in the soil. Despite being commonly assumed to possess kinetic trapping mechanisms like Venus flytraps and Bladderworts, pitcher plants instead are static and use other techniques to catch insects. Sarracenia initially lures insects by secreting nectar from extrafloral nectaries located on the external surface of the pitcher, the hood (operculum) and the lips (peristome). Additionally, Sarraceniahave a smooth, waxy surface coating the interior of the pitcher which aids in destabilizing the footing of insects. Deeper into the pitcher, downward pointing trichomes prevent insects from climbing back out, leading to the bottom of the pitcher. At the bottom of the pitcher, liquid consists of self-made digestive enzymes (proteases, phosphatases, nucleases, etc.) help to drown and digest trapped insects.
In cultivation, Sarracenia are fairly easy to maintain, so long as their requirements are met. Here at the UC Davis Botanical Conservatory, Sarracenia are grown outdoors and unprotected year-round, where they receive full sun and sit constantly in mineral free, deionized water. In our collection, various hitchhiking sundews such as Drosera auriculata and Drosera capensis can often be found growing in many of our Sarracenia pots as well. As a cold hard perennial, Sarracenia enters a cool dormancy period triggered by reduced light levels and colder temperatures, beginning in late fall and lasting anywhere between three to five months.
Dormancy is needed for plants to conserve energy and sugars during a period of unfavorable conditions. During dormancy, plants go through a phase of rest where pitcher and flower production stalls, followed by the browning and drying of the tops of existing pitchers (with notable exceptions such as S. purpurea, S. rosea, and S. psittacina, which retain many of their pitchers). Phyllodia are also produced, which are flattened non-carnivorous leaves to maximize photosynthesis during the winter months. Plants must remain sitting in water during this time as well. Although dormancy can be avoided for several years, as with a few teaching specimens found directly inside the conservatory greenhouse, dormancy is necessary for plants to thrive long term. Emerging out of dormancy in early spring, flowers are produced prior to the growth of new pitchers to avoid trapping pollinators. Plants can be propagated by rhizome divisions and repotted just before this period, into a soil mix consisting of one part peat moss and one part perlite. Pitchers are subsequently produced in spring and last into late fall, where the growth cycle restarts. During this time of active growth, our Sarracenia collection does not receive supplemental fertilizers and relies on the surrounding insect population to nourish them.
Similar to Sarracenia, the genus Heliamphora or “sun pitchers” lure and attract insects using a small “nectar spoon” instead of an operculum to produce nectar, leading insects to fall and drown in their pitfall traps. Heliamphora consists of 24 named species, and hail from the Guiana Highlands of Venezuela, Brazil, and Guyana, where they grow on windswept and rainswept plateaus, clustering in open vegetation pockets. Dissimilar to Sarracenia, Heliamphora do not produce their own digestive enzymes to break down insects, and instead rely on symbiotic bacteria to break down their prey into usable nutrients. In our collection, Heliamphora grow as cool-growing tropical perennials alongside our intermediate and highland Nepenthes collection, receiving temperatures of 70F to 77F during the day and nighttime drops to around 60F. Despite having tested various soil mixes on our Heliamphora collection, our plants have done best in equal parts long fiber sphagnum moss, perlite, and orchiata orchid bark.
Darlingtonia californica, commonly known as the “cobra lily”, is a monotypic genus similar to Sarracenia originating from fens fed by snowmelt in northern California and Southern Oregon. Unlike Sarracenia, Darlingtonia uses a curled operculum with translucent spots to confuse and lure insects down into the pitchers, eventually drowning them in a liquid-filled basin for digestion. Darlingtonia also have a reputation for being difficult to keep in cultivation, as their roots possess ion pumps only functional at a limited range of low temperatures, making their roots especially sensitive to our hot, dry weather conditions in Davis. In our collection, Darlingotnia are kept identical to our Heliamphora collection to keep temperatures consistently cool, but sit permanently in deionized water.