1. Bignonia capreolata L. (cross vine, quarter vine)

Anisostichus capreolata (L.) Bureau

Pl. 304 f, g; Map 1280

Plants lianas, creeping or climbing, with leaf tendrils, lacking adventitious rootlets. Stems to 25 m long, glabrous or inconspicuously hairy at the nodes, finely ridged, the older ones often angled, the dark grayish brown bark becoming wrinkled and sometimes peeling in thin, papery strips. Leaves opposite, compound with 2 lateral leaflets and a terminal, branched tendril, relatively short-petiolate. Leaflets 4–18 cm long, lanceolate to elliptic or oblong-ovate, shallowly cordate at the base, rounded or more commonly tapered to a sharply pointed tip, the margins entire or slightly irregular, the surfaces glabrous or sparsely pubescent with minute, unbranched hairs along the main veins. Inflorescences axillary clusters. Calyces 6–9 mm long, shallowly 5-lobed or without lobes, glabrous or minutely hairy along the margin, reddish green, the lobes (when present) much shorter than the tube, broadly and bluntly triangular. Corollas 4–5 cm long, somewhat zygomorphic, glabrous or more commonly minutely hairy on the outer surface, somewhat thickened, red to reddish orange on the outer surface, yellow to yellowish orange on the inner surface, 5-lobed, only slightly 2-lipped, the tube narrowly bell-shaped and slightly bent toward the middle, the lobes much shorter than the tube, the margins entire or slightly irregular. Stamens 4. Staminodes absent. Fruits 10–20 cm long, flattened, narrowly elliptic in cross-section, the valves glabrous, with a leathery texture, and tan to brown at maturity. Seeds with the body 7–10 mm long, flattened, the body elliptic in outline, 2-lobed, brown, with a wing around the middle (longest at each end) or less commonly only at the ends, the wings papery, light tan, with irregular margins. 2n=40. April–June.

Uncommon, southeastern Missouri in the Mississippi Lowlands Division and adjacent Ozarks (southeastern U.S. west to Oklahoma and Texas). Bottomland forests, swamps, and banks of streams and rivers; also roadsides, fencerows, fallow fields, and wet, disturbed areas.

The leaves of B. capreolata have been called semievergreen. Farther south in the range, they remain evergreen, but in southern Missouri, at the northern edge of the species’ climatic tolerance, they sometimes are shed during the coldest winter temperatures. The unusual foliage and brightly colored, sweetly scented flowers make this an attractive garden ornamental for fences and trellises. However, in plants that climb on trees or poles, the flowers generally become restricted to the upper portion of the plant, too high to be appreciated without binoculars. The common name cross vine refers to the cross-shaped pattern visible in a cross-section of older stems, which develops as a result of anomalous growth in the wood.