CLASS XV. ORDER I.] THLASPI. . 881 



of four equal white ovate petals, tapering into a claw. Fruit a large 

 flat two celled siliqua, with a broad green winged keel, deeply uotched 

 at the apex, style short. Seeds about six in each cell, ovate, dark 

 brown, somewhat rugose, and striated with circular furrows. Pedicles 

 of the fruit slendei, smooth, spreading, about as long again as the 

 fruit. 



Habitat. Cultivated fields and waste places, but not common. 



Annual ; flowering in June and July. 



The leaves, when bruised, have an alliacious smell and warm 

 pungent taste, qualities which caused its being used in the old 

 Mithridate Confection, now completely expunged from the medical list ; 

 hence it has obtained its common name of Mithridate Mustard ; and 

 from the large circular form of the seed vessels it has been called 

 Penny-crest. It is not now used either in medicine or for domestic 

 purposes. 



2. T. perfolia'tum, Linn. (Fig. 1016.) Perfoliate Penny-cress. 

 Leaves smooth, slightly toothed, the radical ones ovate, obtuse, petio- 

 lated, the upper sessile, cordate, ainplexicaul ; siliqua obcordate ; 

 seeds smooth ; style shorter than the lobes of the notch. 



English Botany, t. 2354. English Flora, vol. iii. p. 172. Hooker, 

 British Flora, ed. 4. vol. i. p. 246. Lindley, Synopsis, p. 27. 



Root small, fibrous. Stem erect, round, smooth, branched from the 

 base, leafy, spreading. Leaves a smooth glaucous green, paler beneath, 

 the margin slightly toothed, the radical leaves ovate, obtuse, petiolated, 

 the upper ones sessile, oblong, ovate, with rounded lobes in a heart- 

 shaped form at the base. Inflorescence elongated terminal and lateral 

 racemes of numerous flowers. Calyx small, of four equal concave 

 pieces, with a pale membranous margin. Corolla of four small white 

 ovate petals. Fruit an obcordate smooth siliqua, the keel dilated, 

 especially towards the apex, into rather large rounded lobes, having at 

 the bottom of the notch the very short style, the cells three or four 

 seeded, the seeds small, smooth, ovate, pale brown. 



Habitat. Limestone districts, rare ; Burford and Upper Slaughter, 

 Oxfordshire; Kineton, Gloucestershire. 



Annual ; flowering in May. 



3. T. alpes'tre, Linn. (Fig. 1017.) Alpine Penny-cress. Leaves 

 smooth, entire, or toothed, the radical ones tufted, ovate, obtuse, 

 petiolated, the upper sessile, arrow-shaped, amplexicaul ; siliqua 

 triangular, obcordate ; style longer than the lobes of the notch ; seeds 

 smooth. 



English Botany, t. 81. English Flora, rol. iii. p. 173. Hooker, 

 British Flora, ed. 4. vol. i. p. 247. Lindley, Synopsis, p. 28. 



Root small, tapering. Stems several, from six to twelve inches high, 

 simple, leafy, round, smooth, and like the rest of the plant a pale 

 glaucous green. Leaves wared, or slightly toothed or entire, the 



