1921] 
PAYSON—MONOGRAPH OF THE GENUS LESQUERELLA 133 
must certainly be selected. Watson lists L. occidentalis first 
under this group, and since the relationship of this species is 
clearly with the great mass of species attributed to this genus 
it is here designated as the type species of Lesquerella. 
Acknowledgments.—The student of taxonomy is indebted to 
so many sources for his material that it is quite impossible to 
recognize even some of the most important in a formal manner. 
Personal gratitude may rot be the criterion. The reader has, 
however, some rights in the matter and should know some of 
the sources of the material with which the author worked and 
the facilities at his disposal. 'The present study was made at 
the Missouri Botanical Garden, thanks to the generosity of the 
Director, Dr. George T. Moore, and under the constant super- 
vision of Dr. J. M. Greenman, Curator of the Herbarium. Be- 
sides the collections in the Garden Herbarium specimens were 
borrowed from the United States National Herbarium, the 
Gray Herbarium, the Rocky Mountain Herbarium, the her- 
barium of Mr. George E. Osterhout of Windsor, Colorado, the 
herbarium of Prof. E. Bethel of Denver, Colorado, the Baker 
Herbarium at Pomona College, the herbarium of Mr. C. C. 
Deam, of Bluffton, Indiana, and the herbarium of Mr. I. W. 
Clokey, of Denver, Colorado. 'To the owners and curators of 
these various collections the author is greatly indebted. 
Illustrations.—The illustrations were made by the author 
from herbarium material. The drawings of the trichomes were 
made with the aid of the camera lucida. 
TAXONOMY 
LESQUERELLA Watson, Proc. Am. Acad. 23: 249. 1888; 
Prantl in Engler & Prantl, Nat. Pflanzenfam. III. Abt. 2: 187. 
1891; Coulter, Contr. U. S. Nat. Herb. 2:17. 1891; Wats. in 
Gray, Syn. Fl. N. Am. 1': 116. 1895; Britton & Brown, Ill. 
Fl. 2:136. 1897, ed. 2, 2: 154. 1913; Heller, Cat. N. Am. PI. 
88. 1900; Small, Fl. Southeastern U. S. 468. 1903, ed. 2, 468. 
1913; Rydb. Fl. Colo. 154. 1906; Robinson & Fernald in Gray, 
Manual, ed. 7, 424. 1908; Coulter & Nelson, Manual Cent. 
Rocky Mountains, 218. 1909; Degen, Magyar Bot. Lap. 8: 
3. 1909; Hayek, Beih. Bot. Centralbl. 27: 310. 1911; Wooton 
& Standley, Contr. U. S. Nat. Herb. 19: 274. 1915; Rydb. 
Fl. Rocky Mountains, 331. 1917. 
