44 CRUCIFERAE 



Introduced European weed, rapidly beeuniinjj: distributed all over California 

 at middle and low altitudes. May- Aug. 



Tax. nolo. — The difTeronce hctwiu'n tlu' l>r()fiil lohos of the basal leaves and the filiform divi- 

 sions of the upper leaves is very striking. In age the branches and pods become very rigid and 

 somewhat spreading or divaricate. The pods are quite glabrous or essentially so, with a replum 

 which is slightly prominent and rounded. 



Introduction note. — This species \vith us first appeared near the coastal towns of Southern 

 California about 1910 (Parish, Bull. S. Cal. Acad. 19*: 18) and is now established in widely scat- 

 tered localities throughout the state. It came in earlier in Washington and Idaho where, it has 

 been thought, its appearance was due to introduction from the eastern United States through the 

 building of the Northern Pacific Railroad by James J. Hill. The folk of those states in conse- 

 quence call this weed Jim Hill Mustard, as do settlers in Siskiyou County, California, where the 

 writer first observed plants along the railway lines in 1914. 



Locs. — Laguna Mts., Peirson; Henniger Flats, San Gabriel Mts., Peirson 61; Claremont, 

 D. L. Crawford; Redlands, Jepson 5538; Lytle Creek Wash, Parish 11,141; Tehachapi Pass, 

 II. L. Bauer; Rabbit Valley, San Benito Co., Jepson 12,242; San Francisco, H. A. Walker 5014; 

 Sonoma, P. Kuhn; Andrews Camp, Inyo Co., E. Brandegee ; Cape Horn, Nevada Co., Essig ; 

 Weott, Humboldt Co., Jepson 16,530; Sisson, Jepson 5790; Yreka, Kleaver. 



Eefs. — Sisymbrium altissimum L. Sp. PI. 659 (1753), type European; Gray, Svn. Fl. 

 1>:137 (1895) ; Parish, Muhl. 9:58 (1913), Bull. S. Cal. Acad. 14:15 (1915) ; Dav. Bull. S. Cal. 

 Acad. 13:44 (1914); Jepson, Man. 421 (1925). Norta altissima Britt.; Britt. & Br. 111. Fl. 

 ed. 2, 2:174, fig. 2060 (1913). 



3. S. thalianum J. Gay. Thale Cress. Stems one or several from the base, 

 slender, erect, branching above, 9 to 13 inches high, glabrous above, hirsute below 

 with spreading hairs; leaf -blades of the basal rosette obovate to oblong, entire or 

 nearly so, thinly stellate-puberulent, y^ to ^/^ inch long, narrowed to petioles V2 to 

 as long; cauline leaves few, sessile, mainly hirsute-ciliate; racemes open; petals 

 spatulate, very obtuse or truncatish, white, % line long; pods linear, 4 to 5 lines 

 long, on spreading pedicels 2 to 3 lines long. 



Open ground : Alameda, Lake and Trinity Cos. Introduced from Europe. Apr. 



Locs. — Berkeley, Morton 545, beginning to be established in protected areas in 1926 ; Knox- 

 ville grade to Lower Lake (= f . glabrescens Briq.), Jepson 13,415 in 1892; Oregon Gulch Mt., 

 Trinity Co., Tracy 7537 in 1927. 



Refs. — Sisymbrium thalianum J. Gay, Ann. Sci. Nat. ser. 1, 7:399 (1826). Arahis tha- 

 liana L. Sp. PI. 665 (1753), tvpe from n. Eur. Arabidopsis thaliana Hevnh. ; Holl. & Heynh. 

 Fl. Sachs. 1:538 (1842); Britt. & Br. 111. Fl. ed. 2, 2:176, fig. 2063 (1913). f. gl^vbrescens 

 Briq. Prod. Fl. Cors. 2: 38 (1913), stem and cauline leaves glabrous. 



4. S. irio L. London Rocket. Stem erect, branching above the base, II/2 to 

 2 feet high; herbage glabrous; leaf -blades ovate or lanceolate in outline, 1 to 4 

 inches long, commonly pinnately parted or divided into 1 or 2 pairs of lobes below 

 the large terminal segment which is coarsely toothed to subentire, the petioles ^^ 

 to 11/4 inches long; flowers in a dense raceme, the raceme in fruit becoming loose; 

 petals white; pods spreading, narrowly linear, 1% to 2 inches long. 



European weed, introduced into waste lots and orchards in coastal Southern 

 California. Jan.-Feb. 



Locs. — Claremont (in 1923); Upland and Ontario (in 1918), Bull. S. Cal. Acad. 17:65; 

 Pasadena (in 1926) ; Yorba Linda, G. Byron Deshler (in 1929). 



Refs. — Sisymbrium irio L. Sp. PI. 659 (1753), type European; Parish, BuU. S. Cal. Acad. 

 19*:18 (1920). Norta irio Britt.; Britt. & Br. 111. Fl. ed. 2, 2:174 (1913). 



5. S. sophia L. Flix-weed. Stem branching above the base, li/4 to 1% feet 

 high ; herbage finely pubescent with branched hairs ; leaves finely bi- or tri-pin- 

 natelj' dissected, the segments linear or lance-linear, ^4 to 1^ lines long; pedicels 

 filiform, spreading, 3 to 5 lines long; petals white; pods ascending, narrowly 

 linear, % to 1^4 inches long; seeds in 1 row. 



European weed, introduced in northern California but now appearing in 

 Southern California; rare with us. May- June. 



