Lesquerella fendleri is a species of flowering plant in the mustard family known by several common names, including Fendler's bladderpod, yellowtop, and, simply, lesquerella. It is best known as the richest source of bladderpod oil. Most Lesquerella species contain the hydroxy acid lesquerolic acid in their oil with a seed oil content of ~24%. This oil is useful as a replacement for castor oil in some applications. If the plant becomes more widely cultivated and breeding and refinement techniques are improved, the oil could be used in a number of industries, including cosmetics, coatings, plastics, and lubricants. One obstacle to use is the oil's reddish-brown color, which makes it less valuable for certain applications than the colorless or pale yellow castor oil. Breeding may reduce the pigment load of the lesquerella's oils over time. Breeding may also favor other characteristics in lesquerella, such as its capacity for cultivation in other climates, male sterility to allow better control of pollination, and tolerance for a wider array of soil types.
The plant has uses beyond its oil. The seed coat of L. fendleri also contains a useful natural gum which might be viable as a food additive similar to xanthan gum. The mash is high in protein, and has a similar proportion of various amino acids to the soybean. It may prove to be a good animal fodder.
It is native to the southwestern United States and northern Mexico. It is also cultivated in this area, as it does best in the climate of the region and in local calcareous soils. Lesquerella requires less irrigation than many other crops, due to its adaptation to life in an arid region.
Lesquerella fendleri is a perennial plant in nature, but which is cultivated as a winter annual. It produces hairless capsules called siliques which contain 6 to 25 seeds each.