This section is from the book "British Wild Flowers - In Their Natural Haunts Vol5-6", by A. R. Horwood. Also available from Amazon: A British Wild Flowers In Their Natural Haunts.
The habitat of this plant is woods and shady places, hedgebanks, and thickets. The habit is diffuse, the stem short without a true sobole. The leaves are prolonged, heart-shaped, dark-green. The flowers are small, pale-violet, with a long spur flattened, slender, entire, darker than the petals, not furrowed. The petals are oblong, lilac, narrow, the lower with few parallel nearly simple veins not reaching the margin. The calyx segments are small, indistinct, and hardly produced in fruit. The anther spurs are lance-shaped, narrow. The flowering branches are in the axils, with a central rosette of leaves. The stigma is hooked with a horizontal beak. The fruit-stalks are erect. The plant is 2-6 in. in height. It is in flower between March and August, and is a herbaceous perennial.
The habitat of this plant is copses, woods, thickets, hedgebanks, and heaths. The habit is similar to that of the last. The stem is short, branched, smooth, with a very short rootstock below. The leaves form a rosette. They are heart-shaped, prolonged. The flowering stems are in the axils. The flowers are violet-blue, with broadly egg-shaped petals, handsome, large, the spur broad and short, pale, flattened, furrowed. The lower petal has many branched veins reaching the margin. The sepals are produced at the base in fruit. The capsule is smooth, 3-angled. The plant is 2-6 in. in height, and flowers in April up till September, and is a herbaceous perennial.