27. Scutellaria L. (skullcap)

Plants perennial herbs (annuals or shrubs elsewhere), sometimes with slender rhizomes. Stems erect or ascending, sometimes from a spreading base, bluntly to sharply 4-angled, unbranched or branched, glabrous or variously hairy. Leaves petiolate or sessile, the petiole unwinged or narrowly winged, usually lacking a strong fragrance when crushed. Leaf blades variously shaped, unlobed, the margins entire or variously toothed, the surfaces glabrous or more commonly hairy, the undersurface or sometimes both surfaces often with inconspicuous sessile glands. Inflorescences axillary and/or terminal, the flowers 2 per node, either solitary in the axils of leaves or solitary in the axils of the bracts of slender, usually elongate racemes, these sometimes appearing in groups of 3 at the stem tip, the pair of flowers at each node short-stalked, subtended by a pair of short, leaflike bracts; bractlets absent or minute and inconspicuous. Calyces zygomorphic, with a prominent, transverse, ridgelike or shieldlike projection extending from below the midpoint on the upper side of the calyx tube, otherwise more or less symmetric at the base and bell-shaped, the tube not or faintly 5-nerved, glabrous in the mouth, often becoming closed apically after the corolla has been shed, variously hairy externally, 2-lipped, the lobes shallow and much shorter than the tube, similar in size and shape, both unlobed and broadly rounded, not spinescent, becoming slightly enlarged and leathery or papery at fruiting. Corollas strongly zygomorphic, light blue to blue, bluish purple, or purple (pink or other colors elsewhere), often with a white tube, rarely entirely white, the lower lip lacking markings or with irregular white mottling and sometimes darker bluish purple to blue spots, the outer surface moderately to densely pubescent with glandular and/or nonglandular hairs, the tube often somewhat S-shaped in outline (except in S. lateriflora with a nearly stright corolla tube), narrowly funnelform above the often abruptly upward-curved basal portion, glabrous or hairy in the throat (the apparent hairs in some species attached to the filaments rather than the corolla), shallowly to moderately 2-lipped, the upper lip entire or very shallowly notched at the tip, deeply hooded, the lower lip noticeably longer and broader than the upper lip, spreading or arched, 3-lobed, the lateral lobes usually relatively short, broad, and rounded, usually partially fused to the upper lip (and sometimes appearing more part of the upper lip than the lower one), the middle lobe often longer and/or broader than the lateral lobes, often somewhat folded or distorted at the base to more or less close the corolla throat, sometimes shallowly notched at the tip. Stamens 4, not exserted (ascending under/in the upper corolla lip), the anthers of the slightly shorter upper pair with 2 fertile pollen sacs, those of the lower pair with only a single fertile pollen sac, the anthers small, the connective short, the pollen sacs (of the upper stamens) slightly angled to nearly parallel. Ovary deeply lobed, the style appearing nearly basal from a deep apical notch. Style not or only slightly exserted (ascending under/in the upper lip), very unequally 2-branched at the tip (one of the branches sometimes absent or nearly so). Fruits dry schizocarps, separating into 1–4 nutlets, these 0.9–2.0 mm long, broadly depressed-obovoid to globose, rounded at the tip, the surface yellowish brown or more commonly dark brown to black, glabrous, finely warty or with prominent, blunt tubercles. About 350 species, nearly worldwide.

Some species of Scutellaria are cultivated as ornamentals and a small number of species have medicinal value. The genus is easily recognized by the combination of the calyces with a characteristic projection on one side near the base and the corollas with the upper lip strongly hooded (helmetlike). Steyermark (1963) is well-known for his description of the calyces of Missouri species of Scutellaria as helmetlike or resembling tractor seats, but regrettably in today’s world few students or botanists have experience with tractors and thus do not know the appearance of a tractor seat (and most nonmilitary helmets today are shaped differently).