Arabis.] VI. CRUCIFER^E. 31 



very scarce, and it will probably soon have to be expunged from our 

 Floras. FL spring. 



8. A. petrsea, Lam. (fig. 63). Northern R. — A small perennial, in 

 some respects intermediate between Arabis and Cardamine. Stems 

 branched at the base, loosely tufted, or shortly diffuse, or almost creep- 

 ing, but seldom above 6 inches long. Eadical and lower leaves obovate 

 or oblong, stalked glabrous or with a few stiff hairs, most pinnately 

 divided, with the terminal lobe largest, or some of them nearly entire ; 

 the upper leaves few, narrow, almost entire, tapering at the base. 

 Flowers few, considerably larger than in A. hirsuta, white, or slightly 

 purplish. Pod spreading, rather more than half an inch long, the 

 seeds apparently in single rows. 



In the mountains of northern and central Europe, extending across N. 

 Asia to N. America. In Britain frequent on the higher mountains of 

 northern and western Scotland, and has been found also in Cumberland 

 and North Wales, and very rarely in North-west Ireland. Ft. summer. 



VI. CARDAMINE. BITTERORESS. 



Herbs, either annual or with a perennial rootstock, glabrous, or bear- 

 ing only a few simple hairs ; the leaves pinnate, or, if undivided, on 

 long stalks ; the flowers white or pink. Stigma capitate, or small. 

 Pod narrow-linear; the valves flat without any conspicuous midrib, 

 and usually opening with elasticity. Seeds apparently in a single row 

 in each cell ; radicle accumbent on the edge of the cotyledons. 



A large and natural genus, widely spread over the temperate and 

 colder regions of both the northern and southern hemispheres. The 

 white flowers and pinnate leaves distinguish it from all British 

 Crucifers, except Nasturtium officinale, which differs in its pods. 



Petals large, obovate or oblong, spreading. 

 Stem weak. Segments of the stem-leaves broad. 

 Rootstock slender, with creeping offsets. All the leaves pinnate 1. ft amara. 

 Rootstock thick and knotted. Upper leaves nearly entire, often 



with a bulb in their axil 5. ft bulbifera. 



Stem stiff and erect. Segments of the stem-leaves narrow . . 2. ft pratensis. 

 Petals small, nearly erect. 

 Stem tall and erect. Leafstalk with stipule-like appendages at 



the base 3. ft impatiens. 



Stem low and weak, or much branched. No stipular appendages 4. ft hirsuta. 



1. 0. amara, Linn. (fig. 64). Large B. — Rootstock slender, with 

 creeping offsets. Stem a foot high or more, weak and ascending, or 

 nearly erect. Leaves pinnate, with 5 or 7 distinct segments, all ovate 

 or orbicular, irregularly angled or toothed, the terminal one often an 

 inch long. Racemes few-flowered. Petals nearly as large as in C. 

 pratensis, slightly spreading, of a pure white. Pod about an inch long. 



In wet meadows, and along brooks and streams, generally distributed 

 over Europe and North Asia (except the extreme north), and the 

 western Himalaya, becoming a mountain plant in the south. Widely 

 spread over Britain, but not a common plant. Fl. spring and early 

 summer. 



2. C. pratensis, Linn. (fig. 65). Meadow B., Ladies' Smock, Cuckoo- 

 flower. — Rootstock short and perennial, often bearing small fleshy scales 

 or tubers. Stem erect, simple or branched, near a foot high. Leaves 

 pinnate, the segments of the lower radical ones ovate or orbicular, the 



