White-topped pitcher plant  (Sarracenia leucophylla)

Classified as Vulnerable (VU) on the IUCN Red List (1) and listed on Appendix II of CITES (4).

One of the most beautiful and flamboyant of all pitcher plants (2) (3) (5), the white-topped pitcher plant is a carnivorous plant whose highly modified leaves, or ‘pitchers’, act as pitfall traps to catch prey. The pitcher leaves form tall, slender, gracefully curved funnels, which are held erect, and are covered by a frilly-edged lid, or ‘hood’, which has prominent downward-pointing hairs on the underside (2) (5) (6) (7). As its name suggests, the most distinctive feature of this species is the white-coloured top to the pitcher, which is often richly variegated with red or green veins, giving an almost flower-like appearance (2) (3) (5) (6). During the winter, some flat, sword-shaped, non-pitcher leaves may also be produced (6).

The large, nodding flowers of the white-topped pitcher plant are also very attractive, being red to maroon in colour, and having a sweet scent. Borne on a long, slender, leafless stem, each flower consists of five colourful, petal-like sepals, in addition to the true petals, which hang below. The pistil is an unusual and distinctive umbrella-shape (2) (3) (5) (6) (7). The white-topped pitcher plant shows great variety in appearance (2) (5), and also commonly hybridises with other Sarracenia species (5) (6).

The white-topped pitcher plant occurs in the southeastern United States, where it ranges from northwest Florida to southwest Georgia, and west through Alabama, just into Mississippi (1) (2) (5) (6) (8). The species was thought to have become extinct in Georgia (8) until it was rediscovered at a single site in 2001 (5).

The white-topped pitcher plant is found in savanna bogs and seepage areas, growing mostly in sandy peat soil. Like other pitcher plants, it prefers soils which are moist, acidic and nutrient-poor, although the white-topped pitcher plant tends to be found in more constantly wet areas than other species (1) (3) (6) (8). In its natural state, the habitat of this species is subject to fairly frequent fires, which maintain the open, sunny conditions the plant requires (3).

The white-topped pitcher plant is a perennial (3) (6) (7), producing new leaves each year from an underground rhizome, from which the plant can also regrow after fire (3). Whereas other species may replace lost pitchers throughout the growing season, the white-topped pitcher plant is unique in producing a first set of pitchers in spring, and a second set of larger pitchers in late summer (5) (6). Flowering occurs in spring, between March and April, the five-parted fruit capsule maturing in late summer, and splitting open during autumn to release many small, brown seeds (3) (6) (7).

Like all pitcher plants, the white-topped pitcher plant is found in quite nutrient-poor areas, and has developed a carnivorous lifestyle as a way of supplementing its nutrient intake. Insect prey is lured into the pitcher by a mixture of scents, nectar secretions and bright colours, which mimic attractive flowers or fruits (2) (3) (5) (7) (9). Once inside, a slippery surface and downward-pointing hairs cause the prey to slip into a pool of liquid, where it drowns and is digested by the plant (3) (5) (7). The distinctive pale tops of this species’ pitchers are created by an abundance of window-like structures, formed from groups of cells lacking the green pigment chlorophyll, which may allow more light into the pitcher, encouraging insects to enter (6) (7).

The white-topped pitcher plant’s attractive colouration, together with interest in its carnivorous lifestyle, has made it popular amongst collectors and in cultivation. Unfortunately, although exports of the species have declined, and appear to now be restricted to artificially cultivated specimens, the white-topped pitcher plant is still in great demand within the United States as a cut plant for floral displays, bringing the wild population under threat from overcollection (1) (3) (5) (8) (10). Furthermore, the process of harvesting may damage the pitcher plant’s habitat through repeated foot and vehicle traffic (8).

Perhaps the greatest threat to the white-topped pitcher plant is, however, the loss and degradation of its habitat through wetland drainage, for urban development, conversion to agriculture, and pine plantations (1) (5) (8) (10). The species may also be negatively affected by changes in water quality, including contamination with herbicides and other pollutants, by the spread of invasive plants such as Japanese honeysuckle (Microstigium), and by fire suppression, which allows woody vegetation to encroach on and shade out pitcher habitat (1) (3) (5) (8).

The white-topped pitcher plant is listed on Appendix II of the Convention on International Trade in Endangered Species (CITES), meaning that international trade in white-topped pitcher plants should be carefully controlled (4), and the species is classed as Endangered within the state of Florida, where collection is regulated by permits. However, there is not reported to be any legal protection for the white-topped pitcher plant in Alabama, Mississippi or Georgia, and further study is needed to assess the level and impacts of trade and habitat loss on wild populations. Other recommended conservation measures include developing a management plan for the species, providing collectors with information on less harmful harvesting techniques, and educating vendors and florists about the threats to this popular but vulnerable plant (8).

To find out more about the white-topped pitcher plant and its conservation see:

• International Carnivorous Plant Society:
  http://www.carnivorousplants.org/index.html
• The North American Sarracenia Conservancy:
  http://www.nasarracenia.org/
• Schnell, D.E. (2002) Carnivorous Plants of the United States and Canada. Second Edition. Timber Press, Portland, Oregon.
• Slack, A. (2000) Carnivorous Plants. MIT Press, Cambridge, Massachusetts.