Sisymbrium Cruciferae 489 



1. Thlaspi arvense L. Pennycress. Map 1001. Local in many parts 

 of the state and now possibly established in all parts, although there are 

 no reports from the Lake Michigan area where we would most expect to 

 find it. Most of my specimens are from railroad ballast. Hansen (Proc. 

 Indiana Acad. Sci. 1923: 214-215. 1924) reports it from Randolph and 

 Switzerland Counties and calls attention to its tendency to become a weed. 

 I have found only a few specimens at a place except along an abandoned 

 road in Switzerland County where it was frequent. 



Eu. and Russian Asia; Que. to Man., southw. to N. Y. and Kans. 



2. Thlaspi perfoliatum L. Perfoliate Pennycress. Map 1002. 

 This species was found in 1924 by Miss Edna Banta of Brooksburg, 

 Jefferson County, who reports it to be a frequent to common weed be- 

 tween Brooksburg and Madison, a distance of 8 miles, and in other places 

 in the county. Reported also as occurring on the campus of the Uni- 

 versity of Notre Dame, St. Joseph County. 



Nat. of Eu. 



2917. SISYMBRIUM [Tourn.] L. 



Leaves mostly cauline, pinnate, or pinnatifid; plants generally 4-10 dm high; pedicels 

 stout, about as large as the pod; pubescence, when present, of simple hairs; 

 stigmas 2-lobed; seeds about 1 mm long. 

 Pods 1-1.5 cm long, appressed; petals 2-3 mm long, bright yellow. 



Pods pubescent 1. S. officinale. 



Pods glabrous la. S. officinale var. leiocarpwm. 



Pods more than 1.5 cm long, spreading; petals 5-8 mm long, pale yellow; leaf- 

 segments generally longer and narrower. 

 Stems covered rather thickly all over with long hairs; cauline leaves pinnately 

 parted, usually into 3-7 segments; lateral segments usually 0.5-1 cm wide, 

 the terminal one large and deltoid; mature pods mostly 2-4 cm long. (See 



excluded species no. 256, p. 1051.) S. Loeselii. 



Stems glabrous, or with scattered long hairs, especially on the basal part; cauline 

 leaves pinnatifid, usually cut into 9-19 segments; segments of leaves mostly 

 1-10 mm wide, the terminal one not large and deltoid; mature pods usually 



6-8 cm long 2. S. altissimum. 



Leaves mostly in a basal rosette, entire or slightly toothed; plants generally not over 

 3 dm high; seed about 0.5 mm long 3. S. Thalianum. 



1. Sisymbrium officinale (L.) Scop. (Erysimum officinale in part, 

 of Britton and Brown, Illus. Flora, ed. 2.) Hairy-pod Hedge Mustard. 

 Map 1003. A weed in pastures, waste places, and open woodland and 

 along roads and railroads. My specimens, however, are all from the north- 

 ern part of the state. 



Nat. of Eu. ; local in the ne. U. S. and Canada. 



la. Sisymbrium officinale var. leiocarpum DC. (Erysimum of- 

 ficinale in part, of Britton and Brown, Illus. Flora, ed. 2.) Smooth-pod 

 Hedge Mustard. Map 1004. This is a weed with habitats similar to those 

 of the preceding species but it is much more common and is found through- 

 out the state. 



Nat. of Eurasia; widely distributed in N. A. and S. A. 



