38 BRITISH BOTANY, Q. 



the juniors that anceps means doubtful and uncertain, and that 

 the term by which the plant is known expresses the natm-e of its 

 distinctive characters. 



Sect. II. Petals white ; valves of the fruit with a distinct dorsal nerve. 



N. officinale, Br. Common Water-cress. — e.b. 855. l.b.s. 98. 



A. 18. C. 80. Lat. 50-60°. Alt. 0-200 yds. in England. Tern. 

 52-46°. 



Root perennial. Stems prostrate, rooting, erect at the upper 

 part, branched, thick, succulent, leafy. Leaves pinnate, with 

 rounded or oblong toothed segments, the terminal one being 

 larger and slightly cordate at the base. Petals about double the 

 length of the sepals. Pods curved upwards, rather longer than 

 their pedicels, slightly torulose (with round elevations on the 

 valves), with a short thick point. 



In rivulets, ditches, and watery places. Per.; June-September. 



Var. siifolium. Stem very luxuriant, robust, often an inch 

 thick, and many feet long. Segments of the leaves nearly equal, 

 oblong or obovate, tapering at the base. In deep water. — This 

 plant varies considerably in the form and size of its leaves. Smith 

 says, " the varieties are of no moment." 



TuRRiTis, Lin. — Erect, herbaceous, rough or rigid, biennial 

 plants. Root-leaves toothed or lobed. Stem-leaves clasping. 

 Sepals spreading, scarcely enlarged at the base. Petals not 

 double the length of the calyx. Stigma entire, or almost entire. 

 Pod linear, elongate, compressed. Valves flat, with a prominent 

 longitudinal nerve. Seeds in two rows, compressed, 



T. glabra, Lin. — Arabis perfoliata, Lam. Smooth Tower Mus- 

 tard. — E.B. 777. L.B.S. 94. 



A. 10. C. 30. Lat. 50-56°. Alt. 0-200 yds. in England. Tern. 

 50-47°. 



Root woody, with lateral fibres. Stems erect, rigid, leafy, 

 glabrous, simple or slightly branched (we have seen forms 

 branched from the base, or several stems springing from the same 

 root) ; the branches, when present, are erect. Root-leaves in a 

 rosette, spreading, sinuate, toothed, petiolate, perishing before the 

 plant flowers ; stem-leaves lanceolate, glabrous (sometimes pubes- 

 cent), clasping the stem, auricled. Clusters of pods elongated, 

 erect. Pods erect, somewhat unilateral, elongate, compressed. 

 Seeds minute, in two rows. 



On dry banks and open places. Biennial ; June-September. 



