1. Dracocephalum parviflorum Nutt. (American dragonhead, dragonhead)

Pl. 433 a, b; Map 1945

Plants annual (biennial or short-lived perennial elsewhere), with taproots. Stems 20–80 cm long, erect or ascending, relatively sharply 4-angled, usually branched, sparsely pubescent with minute, curved hairs, sometimes mostly along the angles, more densely hairy around the nodes. Leaves opposite, short- (toward the stem tip) to long- (toward the stem base) petiolate. Leaf blades 2–8 cm long, 1.0–2.5 cm wide, narrowly lanceolate or narrowly elliptic to ovate or broadly lanceolate-triangular, broadly angled or tapered (rarely rounded) at the base, narrowly angled or tapered to a sharply pointed tip, the margins coarsely and sharply toothed, often also hairy, especially toward the base, the upper surface glabrous or sparsely and minutely hairy along the main veins, the undersurface moderately to densely and minutely hairy, also with usually inconspicuous sessile glands. Inflorescences terminal spikelike racemes, more or less continuous (the lowermost few nodes sometimes appearing somewhat distinct), with numerous flowers, these short-stalked (0.5–4.0 mm), each node with a pair of leaflike bracts. Bractlets conspicuous, leaflike, 7–20(–30) mm long, elliptic to narrowly lanceolate, with spinescent teeth along the margins, shorter than to slightly longer than the adjacent calyces. Calyces 8–12 mm long at flowering, 2-lipped (the upper lip with the central lobe longer and broader than the 2 lateral lobes and the 2 lobes of the lower lip), lacking a lateral projection, symmetric at the base, more or less cylindric to narrowly bell-shaped, the tube strongly 15-nerved (-ribbed), glabrous in the mouth, the lobes mostly shorter than the tube, triangular, tapered to spinescent tips, glabrous on the outer surface, becoming slightly enlarged (to 16 mm) and papery at fruiting. Corollas 9–14 mm long, zygomorphic, pink to lavender or light purple, the lower lip often with darker nerves or central spot, the outer surface densely and minutely hairy, the tube funnelform, 2-lipped, the lips shorter than the tube, the upper lip notched at the broadly rounded tip, straight or slightly arched, the lower lip 3-lobed with the central lobe longer than the 2 lateral lobes, arched to spreading. Stamens 4, not exserted (curved under the upper lip), the anthers small, the connective short, the pollen sacs 2, spreading, sometimes becoming more or less parallel after the pollen has been shed), dark purple to bluish purple. Ovary deeply lobed, the style appearing nearly basal from a deep apical notch. Style not exserted, with 2 slender branches at the tip. Fruits dry schizocarps, separating into usually 4 nutlets, these 2.0–2.7 mm long, ellipsoid to narrowly ovoid, the surface black, glabrous, smooth or very finely pebbled. 2n=14. May–August.

Introduced, uncommon, sporadic (northern U.S. [including Alaska] south to New York, Illinois, Nebraska, and Arizona; Canada; introduced sporadically farther south). Margins of crop fields and railroads.