The Rare White Bladderpod

The Center for Plant Conservation (CPC) preserves rare native American plants in a centralized network of 33 botanical gardens within 17 states and the Virgin Islands. In Texas, Mercer Arboretum & Botanic Gardens, San Antonio Botanic Gardens and The Lady Bird Johnson Wildflower Center share the responsibility for the preservation of several rare plants within seed banks or as live specimens. In order to preserve the nation’s rare botanical treasures, Mercer and the CPC’s other member institutions hold partnerships with concerned citizens, private and government conservation organizations, universities and colleges.

Mercer maintains White Bladderpod, Lesquerella pallida, a dainty, winter annual wildflower for CPC’s The National Collection of Endangered Plants. The rare White Bladderpod was registered in 1987 as endangered.

Dr. M. C. Leavenworth discovered Lesquerella pallida on small prairies near San Augustine, Texas in the 1830s. Lesquerella was named in honor of Leo Lesquereux, 1805-1889, renowned bryologist (moss specialist) and America’s first paleobotanist (fossil plant specialist).

White Bladderpod plants reach a maximum height of two feet with gray to yellow-green foliage. The Latin word "pallidus," meaning pale, describes the less than one-inch wide, white flowers the plant bears in April and May. Each flower has a yellow eye and produces a 1/4-inch pea, or "bladder-shaped" fruit in June.

The rare White Bladderpod, Lesquerella pallida, only occurs in the wild in San Augustine County, Texas and grows on open, rocky outcrops of unusual geological regions called Weches formations. Weches formations are bands of ancient marine sediments that lie parallel to the Gulf Coast from Sabine to Frio Counties. In East Texas, these alkaline "islands" of soil contrast the surrounding acid soils of the Pineywoods. The thin top layer of these alkaline sediments contains fossilized calcium-containing marine shells and covers a layer of clay. In San Augustine County, this clay traps water and remains saturated during rainy periods. The clay then becomes very dry during the heat of the summer.

The seeds of Lesquerella pallida, a winter annual, normally germinate in the Weches clay after fall rains and the plants overwinter as small tap-rooted plantlets.

Because the White Bladderpod is isolated within this very unique habitat it is vulnerable to development and is threatened by competition from other plants.

The White Bladderpod’s cousin, Zapata Bladderpod, Lesquerella thamnophila, is another rare Texas native and occurs only in Zapata and Starr counties in West Texas.

The White Bladderpod is a member of the large family of plants named the Brassicaceae Family. Approximately 3,250 members of this family occur worldwide and are often referred to as the Mustard or Cabbage Family. The cross-like arrangement of the four petals found on the flowers of the Mustard Family inspired the former botanical name, the Cruciferae Family. The family is also characterized as bearing two-chambered fruits called capsules or siliques.

The Brassicaceae Family is also economically important. Mustard, Kale, Brussels Sprouts, Cabbage, Broccoli, Cauliflower, Turnips (kinds of Brassica), Radish (Raphanus), Horseradish (Armoracia), Japanese Horseradish (Wasabia) and Watercress (Nasturtium) are a few examples of important food crops. In the 1960s, Canadian horticulturalists bred the nutritionally popular culinary oilseed crop, canola, from the Rapeseed plant, a member of Brassica group. Seeds of certain kinds of Lesquerella are also being studied as a source of fine oil for industrial and cosmetic use.

Many plants in the Mustard Family contain compounds that are irritating to animals eating them and several Mustards (Brassica and Barbarea), Shepherd’s-purse (Capsella) and Peppergrass (Lepidium) often are considered noxious weeds. The infamous "mustard gas" chemicals first used as warfare agents during WWI, however, are not derived from the Mustard Family.

Approximately 40 kinds of Lesquerella occur in North America and Greenland. The yellow-flowered Alpine Bladderpod, L. alpinia, a native of the Rocky Mountains, is grown in rock gardens of cool climates. The common Texas native, Big-flower Bladderpod, L. grandiflora, also bears yellow blooms and is used in sunny flower borders on well-drained soils. Other popular garden members of the Brassicaceae family include ornamental Cabbage & Kale (Brassica), Nasturtium (Tropaeolum), Basket-of-gold (Aurinia), Honesty (Lunaria), Sweet Alyssum (Lobularia), Stock (Matthiola), Rocket (Hesperis), Candytuft (Iberis), Rock Cress (Arabis) and Wallflower (Erysimum).

Stop by Mercer’s Endangered Species Garden in April to see the White Bladderpod covered with snow-white flowers and again in June when they are covered with bladderpods.

Anita A. Tiller, Botanist, Mercer Arboretum & Botanic Gardens, Winter 2001