202 ENGLISH BOTANY. 
Suzs-Stction II.—ANGUSTISEPTA. 
Pod compressed at right angles to the direction of the replum, 
so that the latter lies in the least transverse diameter of the pod, 
the width of which is much greater when measured from the back 
of one valve to the back of the other, than when taken from edge 
to edge, owing to the extreme convexity of the valves, which are 
often keeled or winged. 
TripE [X.—THLASPIDEA. 
Cotyledons flat, with the radicle lying along their edges on one 
side (accumbent), Pod short and broad, compressed at right 
angles to the direction of the replum, generally opening by two 
convex valves, usually with a keel or wing down the central line 
of the back, or part furthest from the replum. 
GENUS XIX. —THLASPI. Lin. 
Sepals sub-erect or spreading, equal at the base. Petals equal, 
entire or slightly notched. Filaments without wings or appen- 
dages. Pods much compressed at right angles to the replum, 
obovate, oblong-obovate, or orbicular ; apex emarginate, notched, or 
obcordate ; valves keeled down the back, the keel produced into a 
wing, most developed towards the apex; style short or elongated. 
Seeds lenticular, not winged, 2 to 8 in each cell of the pod. 
Herbs, generally glabrous and glaucous. Jadical leaves 
attenuated at the base; stem leaves hastate-sagittate, or cordate, 
amplexicaul. Flowers white, rose-coloured, or purple, in short 
racemes which afterwards elongate. 
The generic name is derived from @\éw (thlao), to compress, to break,—in reference 
to the compressed seeds, according to some authors ; others give the derivation from the 
fact that the seeds were broken or compressed, and used like mustard. 
SPECIES I—-THLASPI ARVENSE, Lin. 
Pratt CXLIV.* 
Reich. Ic. Fl. Germ. et Helv. Vol. Il. Tetr. Tab. V. Fig, 4181. 
No rootstock. Stem leaves hastate-sagittate at the base. Pods 
(including the wings) sub-orbicular, obcordate with a deep sinus at 
* The Plate is E. B. 1659, unaltered. 
