CEUCIFERiE. 



75 



XYIII. FENNYCRESS. THLASPI. 



Annuals or low perennials, the leaves usually undivided, the upper 

 ones clasping the stem, the flowers small and white. Petals equal, or 

 nearly so. Pod orbicular or obovate, flattened laterally at right angles 

 to the narrow partition, the valves boat-shaped, their midrib or keel 

 more or less expanded into a green wing surrounding the pod. Seeds 

 two or more in each cell. Radicle accumbent on the edge of the coty- 

 ledons. 



A small genus, spread over Europe, northern and central Asia, and 

 north-western America, distinguished from Candytuft and Cress by 

 having more than one seed in each cell of the pod, from all others by 

 the winged pod. 



Pod (including the broad wing) orbicular, about 6 lines broad 1. Field P. 

 Pod obovate or obcordate, not 3 lines broad. 



Annual. Pod nearly as broad as long, with about 4 seeds 



in each cell 2. Perfoliate P. 



Biennial or perennial. Pod longer than broad, with 6 or 



8 seeds in each cell 3. Alpine P. 



1. Meld Pennycress. Thlaspi arvense, Linn. (Fig. 94.) 

 (Eng. Bot. t. 1659. Pennycress, Mithridate Mustard.) 



An erect, glabrous annual, 6 inches to 

 a foot high or rather more, simple or 

 branched in the upper part. Radical 

 leaves stalked, but soon disappearing. 

 Stem-leaves oblong or lanceolate, usually 

 marked with a few coarse teeth ; the 

 lower ones narrowed at the base, the 

 upper clasping the stem with prominent 

 auricles. Pods in a long raceme, about 

 half an inch in diameter, including a very 

 broad wing, deeply notched at the top, 

 with a very minute style in the notch. 

 Seeds usually 6 in each cell. 



In cultivated and waste places, through- 

 out Europe and Russian Asia. Widely 

 scattered over various parts of Britain, 

 but not so common with us as on the 

 Continent. Fl. spring and summer. 



Fig. 94. 



