cattle, and fair to fairly good for sheep but it is relatively unimportant on the 

 range, because of small size and the fact that the herbage usually desiccates 

 and disappears early in the grazing season, so that the species actually sup- 

 plies but little forage for domestic livestock. Mountain pennycress is a rep- 

 resentative member of the genus Thlaftpi as it occurs natively in the West. 



The genus Thlaspi, usually called pennycress, but also known locally as 

 candytuft, pennygrass, and wild sweet-alyssum, is a member of the crucifer, 

 or mustard family (Cruciferae). Thlaspi (from thlaein, to crush) is a Greek 

 name for a kind of mustard whose crushed seeds were anciently used as a con- 

 diment. It consists of 60 or more species of annual or perennial herbs, widely 

 distributed in temperate, Arctic, and alpine regions, mainly in the Northern 

 Hemisphere, but also occurring in South America, South Africa, and Aus- 

 tralia. At least eight perennial species have been described as native in the 

 western United States. However, there is a great deal of intergradation be- 

 tween these species, and botanists differ in opinion as to the exact number 

 which are tenable and valid. There has been a recent tendency to refer most, 

 if not all, of these American species to the old T. alpestre of Linnaeus, or else 

 to its varieties. In addition to the perennial species of pennycress, the intro- 

 duced field pennycress (T. arven'se), a weedy annual, native to Europe and 

 Asia, is also common throughout the West. 



The native species of pennycress occur chiefly in the mountains in well- 

 drained soils, which often become dry during the summer. These plants make 

 their growth in the. spring and early summer, while the soil is still moist, and, 

 as a result, are largely dormant during the dry period. Generally, the western 

 pennycresses are fair or fairly good sheep feed, and poor to fair cattle forage, 

 although they mature so early in the season that the plants are largely dried 

 up on many of the mountain ranges before much of their foliage can be 

 utilized. The range pennycresses, although common, are seldom abundant 

 and are of only secondary importance for forage. 



Pennycresses are largely characterized by alternate, usually clasping stem 

 leaves broadened at the base into ear-shaped (auriculate) appendages; by 

 small, white or purplish (rarely rose-colored) flowers, four-parted and with 

 six stamens, two of which are shorter than the other four; and by flattened 

 seed pods (siliques), reverse- wedge-shaped, reverse-heart-shaped or rounded 

 in outline, and mostly crested or winged. The pods are two-celled, each cell 

 containing two to eight seeds. The juice is watery and somewhat acrid. 



From an economic standpoint, field peunycress is the most important of the 

 pennycresses in the United States. This plant, known locally as bastard-cress, 

 devilweed, fanweed, Frenchweed, stinkweed, treacle-mustard, and erroneously 

 as Jim Hill mustard, is now well distributed throughout the United States 

 from Maine to Florida and westward to California and Washington. Evi- 

 dently a very early introduction, it is now abundant in many localities, espe- 

 cially in the northern and northwestern parts of the country, where it grows 

 as a pest in fields, meadows, pastures, and other agricultural holdings, and 

 also abounds along roads and in waste lands. It has also become pestiferous 

 in parts of the Jackson Hole country, Wyoming, but, as yet, seems not to 

 be a problem on western forest ranges as a whole. The species is especially 

 detrimental in fields where dairy cows are pastured because, if grazed, it imparts 

 a disagreeable, somewhat garlic-like flavor and odor to the milk. It is a per- 

 sistent enemy of the wheat grower in the Northwest, the seeds spoiling the flour. 1 

 Certain farming lands in Montana 2 are no longer used because of the spread of 

 this plant. Both spring and fall cultivations are necessary in the effective 

 combat of this weed because its seed sprouts during both spring and fall, the fall 

 seedlings often surviving the winter. Field pennycress formerly was a popular 

 substitute for mustard. 3 



1 Beal, \V. J. MICHIGAN WEEDS. Mich. Agr. Expt. Sta. Bull. 267, rev., 181 pp., illus. 

 1915. 



- Bobbins, W. W. FANWEED OH FHENCHWEED. Through the Leaves, Aug. 1920 : 445-447, 

 illus. 1920 



3 Hulme, F. K. FAMILIAR \vii,n FLOWERS. 8 v., illus. London, Paris, New York, and 

 Melbourne. 1905. 



