T. arvense: annual; stem erect; leaves oblong, toothed; flowers small, white. - Mithridate Mustard. - Waste and cultivated ground. Fl. May to July.

T. perfoliatum: annual; stem erect; root-leaves ovate or orbicular, upper ones oblong, stem- clasping; flowers small, white. - Limestone pastures, rare. Fl. April, May.

19. Viola. Violet

* Stem very short, the flowers and leaves appearing to grow from the root.

V. palustris: leaves kidney-shaped, smooth; flowers pale blue, with purple streaks, scentless. - Marshy places. Fl. April.

V. odorata: leaves heart-shaped, downy or shortly hairy; flowers bluish-purple or white, rarely purple reddish or lilac, sweet-scented. - Hedge-banks and thickets. Fl. March, April.

V. hirta: leaves heart-shaped, rough with hairs; flowers pale blue, scentless. - Limestone woods and pastures. Fl. April, May.

** Stem elongated, evident.

V. canina: primary stem short, flowering branches elongated ascending or erect; leaves ovate-cordate; flowers large, pale blue, scentless. There are several varieties. - Hedges, groves, and thickets. Fl. April to July.

V. tricolor: biennial or perennial; stem branching; leaves oblong, deeply crenate, with large lyrately pinnatifid stipules; flowers purple or yellow, or with mixed colours. - Pansy or Hearths-ease, and the origin of the garden Pansies. - Cultivated fields. Fl. May to September.

Var. lutea: flowers large, rich yellow; habit more decidedly perennial. - Mountain pastures.

Var. arvensis: flowers much smaller, with very short whitish petals; annual. - Cornfields.