Subularia. | . VI, ORUCIFERZ. 43 
1, S. aquatica, Linn. (fig. 94). Water Awlwort.—The whole plant 
is but 1 to 2, rarely 3 inches high, and perfectly glabrous, usually growing 
entirely under water. Leaves all ‘radical, nearly cylindrical, slender and 
pointed, 3 to 1 inch long. Flowers few, with minute white petals. Pods 
about a line and a half long, and oblong, or sometimes shorter, and nearly 
globular, with 5 or 6 seeds in each cell. 
In the shallow edges of alpine ponds and lakes, in northern Europe, 
Asia, and America, and more rarely in Central Europe. Scarce in Britain, 
in the mountains of Scotland, north-western England, north Wales, and 
western Ireland. 7. summer. 
XVII. THLASPI. PENNYCRESS. 
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 eel 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 cotyledons. 
A small genus, spread over Europe, northern and central Asia, and 
north-western America, distinguished from [beris and Lepidium, 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. Z. arvense. 
Pod obovate or obcordate, not three lines broad. 
Biennial or perennial. Pod longer than broad, with 6 or 8 seeds 
inéachcell . : : ‘ ‘ 5 : : : . & TL. alpestre., 
Annual. Pod nearly as broad as long, with about 4 seeds in 
each cell : : . : : ° . 2. DL. perfoliatum. 
1, T.arvense, Linn. (fig. 95). Field Pennycress, Mithridate Mus- 
tard.—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, throughout Europe and Russian Asia to 
N.W. India. Widely scattered over various parts of Britain, but not so 
common with us as on the Continent. £1. spring and summer. 
2, T. perfoliatum, Linn. (fig. 96). Perfoliate Pennycress.—A gla- 
brous annual, branching at the base, or nearly simple, the stem ascending 
or erect, 3 to 6 inches high, MRadical leaves spreading or tufted, stalked, 
ovate or orbicular ; upper stem-leaves ovate or oblong, clasping the stem 
with rather large rounded auricles. Pods not half the size of those of 
T.. arvense, with narrower wings, and the notch at the top much broader 
and more open. Style nearly as long, or longer than the notch. Seeds 
usually 4 in each cell. 
In stony pastures and waste places, chiefly in limestone districts, in 
central and southern Europe, and temperate Russian Asia. In Britain, 
apparently confined to a few localities in E. Gloucestershire. 7. spring. 
3, ©. alpestre, Linn. (fig. 97.) Alpine Pennycress.—A glabrous 
