1. Dasistoma macrophyllum (Nutt.) Raf. (mullein foxglove, false foxglove)

Seymeria macrophylla Nutt.

Pl. 471 e–g; Map 2159

Plants annual, hemiparasitic, green or dark green, sometimes purplish-tinged, sometimes blackening upon drying. Stems 100–220 cm long, usually with many branches, erect or strongly ascending, mostly bluntly 4-angled, moderately to densely pubescent with fine, curved, nonglandular hairs, sometimes only on 2 opposing sides, not roughened to the touch. Leaves opposite, sessile or short-petiolate, the petioles winged, at least toward the tip. Leaf blades 10–35 cm long, lanceolate to broadly ovate in outline, those of the lower leaves moderately to deeply 1 or 2 times pinnately lobed or divided, the margins also toothed, those of the upper leaves often only shallowly lobed or toothed, the surfaces sparsely to moderately pubescent with short, slightly broad-based, nonglandular hairs, mostly along the veins. Inflorescences open, terminal, spikelike racemes with leafy bracts, these reduced progressively toward the axis tip, entire or few-lobed, the flowers paired at the nodes, usually appearing as axillary flowers toward the stem tip, the stalks 1–4 mm long, stout, thickened toward the tip, hairy, lacking bractlets. Cleistogamous flowers absent. Calyces 6–8 mm long, becoming distended and slightly elongated to 7–10 mm at fruiting, 5-lobed, slightly zygomorphic, bell-shaped, the tube moderately short-hairy on the outer surface, densely and minutely hairy on the inner surface, the lobes about as long as to longer than the tube at flowering, longer than the tube at fruiting, entire or with 1 or 2 blunt teeth, the surfaces glabrous or sparsely short-hairy, the margins hairy in the sinuses between the lobes. Corollas 14–16 mm long, 5-lobed, weakly bilabiate, yellow, the tube densely hairy on the inner surface, the beard tending to partially block the throat, the lobes shorter than the tube, more or less spreading (1 of the lobes often arched upward), their surfaces glabrous, the margins glabrous or minutely hairy. Stamens with the filaments of 2 lengths, hairy, the anthers with 2 sacs, these more or less parallel, tapered to a minute, awnlike base, light yellow to yellow, glabrous. Style relatively short and stout, not exserted, the stigma more or less capitate, 2-lobed. Fruits 6–11 mm long, ovoid to nearly globose, usually slightly flattened, glabrous. Seeds 2.0–2.5 mm long, irregularly oblong-ellipsoid to more or less trapezoid, usually slightly flattened, the surface with a coarse network of often fine ridges and pits, the ridges sometimes appearing winglike, brown to dark brown or black. June–September.

Scattered nearly throughout the state (eastern U.S. west to Nebraska and Texas). Bottomland forests, mesic upland forests, banks of streams and rivers, and occasionally glades; also roadsides.

Dasistoma macrophylla parasitizes the roots of angiosperm tree species, including such diverse genera as Acer and Aesculus (Sapindaceae), and Ulmus (Ulmaceae) (Piehl, 1962). the flowers are pollinated mainly by larger-bodied and longer-tongued bees (C. R. Robertson, 1891).