Western tansymustard, a green or slightly grayish, slender annual with bright 

 yellow flowers, sometimes bears the book name incised tansymustard, the spe- 

 cific name incisa, meaning cut or incised, referring to the sharply cut leaf 

 divisions. However, western tansymustard is an appropriate name for the 

 species since it is probably the most common, abundant, and widespread of the 

 western United States tansymustards. It ranges from Tennessee, to Minnesota, 

 British Columbia, California, Texas, and Mexico, but does not occur west of 

 the Cascade and Sierra Nevada Mountains. The species inhabits a wide variety 

 of sites from dry, semidesert areas to moist, rich soils in the mountains, ex- 

 tending upward in Colorado to an elevation of about 10,000 feet and to 11,500 

 feet in California. It occurs in partial shade under timber, especially aspen, 

 but is usually most abundant in open exposures. It is often conspicuous along 

 ditches, roadsides, and other places where the mineral soil has been exposed. 



As regards quality, western tansymustard is a poor forage species, its pala- 

 tability under normal conditions never being more than fair for sheep and 

 goats and poor for cattle. It is, notwithstanding, of considerable importance 

 on some of the western ranges which have been badly overgrazed, as it occurs 

 rather abundantly and provides soil protection as well as some forage. 



Tliis species is variable as; to leaves, hairiness, and length of pods. How- 

 ever, the pedicels or stalks of the pods usually stand out from the stem and are 

 shorter than the erect, often somewhat curved pods. 



TANSYMUSTARDS (So'phia spp., syn. Sisym'brium in part) 



Tansymustards, so called because of their more or less tansylike leaves, and 

 because they belong to the large mustard family (Cruciferae, or Brassicaceae), 

 are annual, biennial, or perennial herbs. The most commonly used name of 

 this plant family, Cruciferae, refers to the crosslike arrangement of the four 

 petals of the flowers. Sophia is a Greek word meaning wisdom and probably 

 was applied to this genus because the Old World tansymustard, or flixweed 

 (S. parviflora, syns. 8. sophia, Sisymbrium sophia) "had a name among the 

 herbalists expressive of some virtues which we in modern days do not discover." * 

 The plant was thought serviceable in hysterical cases and as a purgative, but its 

 chief repute was for the healing of wounds. 



All the western species of this genus are annuals or biennials. They are 

 distributed throughout the West in a wide variety of soils and plant types 

 but are most abundant in the open, in fields, along roadsides and ditches, and 

 in other places where the mineral soil has been recently exposed. The palat- 

 ability of tansymustards, in general, is rather low, being seldom better than 

 fair for sheep and goats and poor for cattle. Horses rarely graze these herbs. 

 However, they are sometimes fairly abundant, especially on ranges which have 

 been severely overgrazed, and do provide considerable forage. Like many other 

 annual and biennial species, the tansymustards produce an abundance of seed 

 and are especially adapted quickly to invade areas whose normal plant cover 

 has been reduced. Under similar growth conditions they cannot compete with 

 perennial weeds and grasses, but usually these perennial species are more pal- 

 atable and are closely cropped and gradually killed out. The shorter-lived 

 plants, thus freed from the competition of the perennials, increase in abun- 

 dance, and hence constitute an indication of severe past overgrazing. 



The tansymustards are definitely identified as belonging to the mustard 

 family by the characteristic sharp, pungent taste ; the four separate outer 

 flower parts (sepals); the four separate petals; and the six stamens of 

 which two are shorter than the others. They are further distinguished by the 

 yellow, yellowish, or rarely white flowers born in rather narrow clusters 

 (racemes) which become much lengthened in fruit, and by the pods (siliques) 

 which are seldom over % of an inch long, but are several times longer than 

 wide. The pods are 2-celled, with a thin membrane between the cells, and 

 split open at maturity, discharging the minute seeds which are in one or two 

 rows in each cell. The leaves are alternate and usually much divided. Most 

 species are more or less hairy ; the hairs, when present, are typically two- 

 branched and attached by the middle or else star-shaped. 



1 Pratt, A. THE FLOWERING PLANTS, GRASSES, SEDGES, AND FERNS OF GREAT BRITAIN . . 



New ed., rev. by E. Step, 4 v., illus. London and New York. 1899-1900. 



