This section is from the book "British Wild Flowers - In Their Natural Haunts Vol2-4", by A. R. Horwood. Also available from Amazon: A British Wild Flowers In Their Natural Haunts.
This is another marsh plant which is one of the Arctic species not found in early deposits as yet. It is found to-day in the Arctic and Temperate Zones in Arctic Europe, N. Africa, N. Asia, as far east as N.W. India, and N. America. In Great Britain it does not grow in N. Somerset, Monmouth, Carmarthen, Mid Lancs, Haddington, Mid Perth, S. Aberdeen, Easterness, Caithness, or Northern Isles, except the Isle of Harris. It is rare in Scotland and local in Ireland.
The Blue Skull-cap is a familiar waterside plant, which is distinctly hygrophilous, occurring by the side of most tracts of water, such as ditches, streams, rivers, and also by the margins of pools, ponds, and lakes. It is found also in damp places in woods in the shade, and is frequent in bogs and marshes.
It grows in small clusters or groups, with an erect, quadrangular, concave or hollow stem, with oblong, heart-shaped, blunt, stalked leaves, scalloped, acute at the top, and serrate or coarsely toothed.
The flowers are blue, in pairs, all turned one way, axillary, softly and loosely hairy, and whitish below. The calyx has a blunt mouth, with a scale acting as a lid, and the first Latin name refers to its shape, the second having reference to the corolla, which is white inside, much longer than the calyx and gaping, with a short turned-back tube, and the throat long, with hollow upper lip, the lower lip ending in a notch.
Skull-cap is 2-3 ft. high. The flowers may be met with from June to September. It is perennial, and propagated by division.
The tube of the corolla is long, smooth inside, with an expanded throat as in other long-tubed labiates. The upper lip is 3-lobed and has a small surface adapted to butterfly visits, the lower dilated with spreading lateral lobes. The opening between the two lips is large enough for humble bees. There are 4 anthers. The anthers are in pairs and ripen first, fringed with hairs to hold the pollen, with 1 cell in the lower, 2 in the upper. The style has a short upper lobe, and both it and the stamens are included. There are complete flowers, and others with the anthers undeveloped. They may be on the same or on different plants. Skull-cap is visited only by the Brimstone, Rhodocera rhamni.
Photo. Chas. Allen - Skull-cap (Scutellaria Galericulata, L.)
The nutlets fall when ripe automatically just around the parent plant. The calyx on the fading of the corolla closely envelops the ovary and protects the seeds, being a helmet-like hood.
This is a peat-loving plant, requiring a moist humus soil or peat soil.
A beetle, Phyllobrotica quadrimaculata, and a moth, Choreutis scintillullana, are found upon Skull-cap.
Scutellaria is from the Latin scutella, a shield, from the shape of the calyx, and the second Latin name refers to the helmet-shaped corolla.
The plant is called Hooded Willow Herb as well as Skull-cap, both alluding to the shape of the upper lip.
Essential Specific Characters:254. Scutellaria galericulata, L. - Stem erect, stout, leaves ovate, serrate, cordate below, flowers blue and white, opposite, axillary, the tube exceeding the calyx.