Spring Creek bladderpod  (Lesquerella perforata)

Classified as Endangered on the IUCN Red List of Threatened Plants 1997 (1) and listed as Endangered on the U.S. Endangered Species Act 1967 (3).

Bladderpods (Lesquerella) earn their unusual name for the inflated, rounded shape of their fruits, or pods (4) (5). The fruit of the Spring Creek bladderpod is somewhere between egg- to pear-shaped, and is smooth to sparsely hairy on the outside, but densely hairy on the inside (2) (5). The flowers are made up of four white to pale-lavender petals, which are yellow at their base, giving the appearance of a yellow centre to the flower (4) (5). A blanket of fine to coarse hairs covers the stems and leaves (5).

Confined to a small area within Tennessee’s Central Basin in the United States (4).

Typically found on creek floodplains (of Spring Creek, Bartons Creek and Cedar Creek), but also in agricultural fields, flooded pastures and glades (open spaces with few or no trees). This rare species appears to require some degree of annual disturbance to survive, ideally occurring after fertilisation and before germination. Disturbance comes in the form of scouring from natural flooding, or ploughing of the soil on agricultural lands. This disturbance helps remove perennial grasses, herbs and other woody plants (5).

The Spring Creek bladderpod has an annual life cycle. The plant germinates between September and October and spends the winter as a small rosette of leaves, waiting until the spring before it fully develops and begins to flower. Flowers usually blossom in March and April (4) (5), and once fertilised, the fruit begins to mature and the flowers wither (4). The fruit splits open upon maturity in late April and May and the plant dies shortly after (5). The enclosed seeds fall onto the ground, where they lie dormant until the autumn, at which point the life cycle begins again with seed germination (4).

Like other bladderpods, individual plants of this species are unable to self-fertilise, and reproduction therefore requires cross-pollination with other individuals (5).

The continued survival of the Spring Creek bladderpod is threatened by habitat loss in its already limited range, as a result of rapid residential, commercial and industrial development (4) (5). Additional threats include conversion of land to uses other than cultivation of annual crops, such as to pastureland for grazing livestock, and encroachment of the plant’s habitat by woody and herbaceous perennials (4) (5). Unless a site is ‘disturbed’ in some way every few years, populations of this rare plant quickly dwindle, and agriculture has been the primary mechanism by which suitably disturbed habitat has been maintained in the recent past. However, agricultural practices within Tennessee’s Central Basin are declining as the demand for residential development increases. Furthermore, the associated construction of new and improved sewer, water and gas lines are often located along streams, precisely the habitat the Spring Creek bladderpod occupies. Any damning or alteration of the three creeks (Spring Creek, Bartons Creek and Cedar Creek) around which it lives pose a further potential threat to the species, since natural flooding is important in dispersal of seeds to newly disturbed sites (5).

The Endangered Species Act protects endangered plants on Federal lands, but no known populations of Spring Creek bladderpods are located on federal land. Commercial exploitation or wilful destruction of these plants on privately-owned land is also illegal by anyone other than the landowner, but this law does not prevent landowners from destroying plants on their own land. Furthermore, it is not considered a violation to destroy the plants in the name of public works projects such as road construction, or in the course of routine forestry or agricultural practices. Nevertheless, all landowners have been contacted about the location of Spring Creek bladderpods on their property, and three landowners to date have agreed to protect the plants on their land through various means of management, providing protection for approximately 4,000 plants in total. A Recovery Plan has also recently been formulated for the Spring Creek bladderpod, identifying important targets and management strategies for the future conservation of this rare endemic plant, which will hopefully help ensure its long-term survival in Tennessee (5).

For more information on the spring creek bladderpod, see:

• Center for Plant Conservation:
  http://www.centerforplantconservation.org/Collection/CPC_ViewProfile.asp?CPCNum=2512
• U.S. Fish and Wildlife Service. (2005) Technical/Agency Draft Recovery Plan for Lesquerella perforata (Spring Creek Bladderpod). USFWS, Atlanta, Georgia. Available at:
  http://www.fws.gov/cookeville/Spring_Creek_Bladderpod_recoveryplan_7_7_05.pdf