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 habit of this species is that of a hemi-parasite. The stem is tall, branched below, glandular, the hairs long and scattered. The leaves are plaited, not more than twice as long as broad, finely furrowed, clothed with white bristles, and glandular, the hairs long and wavy. The stem-leaves are ovate, acute, with a short point, the teeth, 6-12, being acute. The floral leaves are broadly ovate, with as many teeth. The spike is long. The flowers are white with violet markings. The calyx is bristly and glandular, with triangular to lance-shaped segments. The tube of the corollalenglhens ! after flowering, the upper lip having the lobes turned back, notched or divided into two. The fruit is elliptical, notched, fringed with hairs, and clothed with silky hair, not much longer than the calyx.
This species has been referred to E. officinalis var. tuinor, Gaud., fil, rectipila, Williams, by F. N. Williams (Prodr., p. 303). It differs in the smaller flowers, darker shade of the corolla, less hairy leaves, more slender habit. There are no long-pointed hairs tipped with glands on the upper part of the stem.
Euphrasia brevipila, Born, et Gren. ( = Euphrasia stricta, Host.). - The habitat of this plant is pastures. It belongs to a group with small flowers, with leaves not more than twice as long as broad. After the flower opens the tube of the corolla does not lengthen, being 6-10 mm. long, and therefore adapted to short-lipped insects. The stem is branched at the base, and without glands. The leaves are almost devoid of hair, or with a few short and glandular hairs. The stem-leaves are ovate to oblong, acute or blunt, the teeth, 6-10, blunt, acute, or awned. The spike lengthens in fruit. The bracts are ovate, the base short and wedge-shaped, broader than, and not so long as, the stem-leaves, with 8-14 awned or pointed teeth. The flowers are pale-violet, blue, or white. The calvx has short glandular hairs and triangular lance-shaped teeth. The corolla is large, the upper lip having notched lobes, or the lobes may be entire or toothed. The fruit is oblong or wedge-shaped to inversely ovate, blunt or notched, longer than the calyx.
The habitat of this plant is chalky and calcareous pastures, limestone areas in central and S. England. The northern limit is Derbyshire. The stem is without glands. It is usually branched at the base. The leaves possess no glands, but have small bristles on the margins and veins. The stem-leaves are ovate to elliptic, acute, with 8-14 teeth, which are triangular to acute. The flowers are white, with purple stripes. The spike lengthens. The bracts are oval, acute, and have 6-12 pointed teeth. There are no glands on the calyx, and the teeth are rough, lance-shaped, and pointed. The corolla is large, and longer than the calyx at length, the upper lip being sometimes of a violet colour, with the lobes turned-back and divided into two. The fruit is oblong, inversely ovate, notched, fringed with hairs, with soft hair.
Euphrasia minima, Gaud. (= Euphrasia borealis, Wettst.). - The difference between the two plants lies in the more softly hairy character of the one under description, the capsule also equalling the calyx, or it may be shorter. The stem is simple, stout, sometimes branched below, without glands. The leaves are erect to spreading, more or less without hairs, or stiffly hairy. The stem-leaves are ovate, blunt. There are 6-10 blunt or acute teeth. The spike is dense. The bracts are broadly ovate, with 6-10 acute, shortly-awned, or blunt teeth. The flowers are white or violet. The calyx is devoid of hairs, with triangular to lance-shaped teeth. The corolla is large, with a violet upper lip, and the lower white, the lobes of the upper lip turned-back, notched or toothed. The capsule is elliptic or oblong, narrow below, notched, fringed with hairs.