170 



BRITISH FLORA 



flowering in April and May, and is a herbaceous 

 annual ur biennial. 



Whitlow Grass (Erophila pracox, Stev. = E. 

 brachycarpa (Ord.), D.C.). The habitat of this 

 species is walls and dry places. From E. verna 

 it differs in the flattened pods, which are inversely 

 ovate to oblong, rounded, one to one-and-a-half 

 times as long as broad. The cells contain 12-20 

 seeds. The flowers are white. The plant is 1-4 in. 

 high, flowering from March to June, and is a 

 herbaceous perennial. 



Erophila inflata, Wats., Hook, fil. The habi- 

 tat of this plant is mountain rocks, and the plant 

 is rare. The pods are turgid, round in section, 

 ovoid to oblong, twice as long as broad, and the 

 cells contain 20-40 seeds. The flowers are white. 

 The plant is 1-3 in. high, flowering from March to 

 July, and is a herbaceous annual. 



E. virescens, Jord. In this plant the hairs are 

 all or nearly all simple. The stem is slender, sub- 

 erect, flexuose, short. The leaves are more or less 

 narrow lance-shaped, oblong or ovate. The sepals 

 are clear-green, the silicles 4x2 cm., the style 

 longer, the plant 6-7 cm. 



Thale Cress (Sisymbrium Thalianum, J. Gray 

 = Arabis Thaliaita, L.). The habitat of this plant 

 is dry soils, hedgebanks, cultivated ground, walls, 

 &c. It is a native of wood borders, stream banks, 

 rocks, and woods. The plant has the rosette 

 habit. The stems are slender, leafless or nearly 

 so, much-branched. The leaves are mainly radi- 

 cal, entire, toothed, downy, oblong, lance-shaped, 

 stalked, the stem-leaves narrow, stalkless, entire 

 or toothed. The flowers are small, white, on 

 slender, spreading stalks. The pods are spread- 

 ing or ascending, slender, curved, bluntly 4-angled, 

 linear, twice as long as the stalks, not convex 

 tlorsally, the lateral longitudinal veins obscure. 

 The seeds are very small, oblong, not furrowed. 

 The plant is 6 in. to i ft. high, flowering from 

 May to September, and is a herbaceous annual. 



Wall Rocket (Diplotaxis muralts, D.C.). The 

 habitat of this plant is waste places, limestone 

 rocks, and walls. The plant has the rosette habit. 

 The stem is simple, leafless, hairy. The leaves 

 are hairless, long-stalked, wavy or divided nearly 

 to the base, egg-shaped, lance-shaped, blunt. 

 The scapes are slender, ascending. The flowers 

 are yellow, on stalks of the same length, the 

 petals 2-3 times as long as the sepals, inversely 

 egg-shaped, notched or abrupt, roundish, with 

 a short claw. The style is not narrowed below, 

 stout, straight. The pods are slender, narrowed 

 at the top only, the valves flat, nerveless. The 

 seeds are in two rows (hence Diplotaxis). The 

 plant is 6-18 in. high, flowering between June 

 and September, and is a herbaceous annual or 

 biennial. 



Narrow-leaved Pepper Cress (Lepidium ruder- 

 ale, L.). The habitat of this plant is waste places, 

 chiefly near the sea, and it is scarcely wild except 

 along the coast. The habit is erect or prostrate. 

 The plant is smooth or slightly downy. The radical 

 leaves, which soon wither, are much divided, bipin- 

 natifld, with narrow lobes. The upper stem-leaves 



are linear, entire. The flowers are in terminal 

 and lateral corymbs, small, white, sometimes apet- 

 alous. There are 2 stamens. The style is short. 

 The pods are oval, narrowed at the end, flat, with 

 a wing, the valves keeled. The seeds are flattened. 

 The plant is 6-12 in. high, flowering from May to 

 July, and is a herbaceous annual. 



Perfoliate Penny Cress ( Thlaspiperfolialum, L. ). 

 The habitat of this plant is calcareous places, 

 on limestone. The habit is erect. The stems are 

 branched above, forming a panicle. The branches 

 are ascending, wavy. The stem-leaves are deeply 

 heart-shaped, oblong, with auricles which meet 

 together, and smooth, bluish-green. The radical 

 leaves are spoon-shaped, stalked. The flowers 

 are white, in a raceme or corymb, longer in 

 fruit. The style is very short, included within 

 the notch. The pods are small, inversely heart- 

 shaped, horizontal, like the stalks, the valves 

 broadly winged above, turgid, the marginal nerve 

 short. The seeds are 4-6 in a cell, pale, smooth. 

 The plant is 3-8 in. high, flowering in April and 

 May, and is a herbaceous annual. 



Alpine Penny Cress (Thlaspi alpestre, L.). 

 The habitat of this plant is mountain pastures, 

 stony places. The habit is erect. The radical 

 leaves are long-stalked, inversely ovate, entire. 

 The stem-leaves are arrow-shaped, narrow, heart- 

 shaped, smooth, and bluish-green. The flowers 

 are white, with a rose tinge, small, in racemes. 

 The style equals the notch. The pods are oblong 

 to inversely ovate, narrowed below, and are 

 curved upwards on spreading stalks, the valves 

 winged above. The marginal nerve is indistinct. 

 The seeds are reddish-brown, smooth, 4-8 in a 

 cell. The plant is 4-15 in. high, flowering from 

 May to October, and is a herbaceous biennial or 

 perennial. 



Thlaspi virens, Jord. The habitat of this plant 

 is limestone rocks. It differs from the last in having 

 nearly entire leaves. The stem-leaves are oblong, 

 heart-shaped. The flowers are small and white. 

 The style is longer than the notch. The raceme 

 is oval or oblong in fruit. The petals are three 

 times as long as the calyx. The pods are blunt, 

 notched at the tip, with a point (the style), in- 

 versely ovate, the notch broad and shallow. The 

 seeds are 4-5 in each cell. The plant is 6-10 in. 

 high, flowering from May to August, and is a 

 herbaceous perennial. 



Hutchinsia petrcea, Br. The habitat of this 

 plant is limestone rocks and sand dunes, and 

 about walls. It was planted by Dillenius on the 

 wall of Eltham Churchyard in Kent, and in 

 Mathew Cemetery, York. The habit is prostrate. 

 The stems are smooth or hairy, slender, leafy, 

 branched. The radical leaves have spreading 

 lobes, and are inversely ovate, nearly stalked. 

 The leaves are deeply divided to the base, the 

 segments entire, much-branched from the base. 

 The flowers are in racemes, small, white. The 

 petals are as large as the sepals. The style is 

 distinct. The pods are on horizontal stalks, the 

 raceme loose, long in fruit, the pods blunt both 

 ends. The seeds are pale. The plant is 2-4 in. 



