1. Maclura pomifera (Raf.) C.K. Schneid. (bois d’arc, Osage-orange, hedge apple, bowwood)

Pl. 458 a, b; Map 2080

Plants trees or shrubs to 20 m tall, when young, the branches often armed with stout, straight thorns to 2 cm long in the leaf axils, with milky sap. Bark thick, developing deep furrows and coarse ridges on older trunks, the ridges with the surface often peeling in thin strips with age, brown to brownish orange. Twigs relatively stout, sometimes developing into short, very congested shoots, on elongate shoots often somewhat zigzag, greenish yellow to orangish brown with circular to oval, lighter lenticels, glabrous or minutely hairy, the winter buds often paired (then of unequal sizes), globose, with several overlapping scales, these minutely hairy along the margins. Leaves alternate, but appearing more or less whorled on short shoots. Petioles 1–4 cm long, short-hairy, sometimes also with scattered, longer, spreading hairs. Leaf blades 4–14 cm long, 2–7 cm wide, ovate to elliptic or narrowly ovate, unlobed and with 1 main vein (pinnately veined) from the base, abruptly short-tapered to a sharply pointed tip, rounded to truncate or broadly angled at the base, the margins otherwise entire, the upper surface green, smooth, with the main veins more or less hairy, the undersurface pale green, sparsely short-hairy, at least along the main veins. Inflorescences entirely staminate or pistillate. Staminate inflorescences clustered on short shoots, dense, more or less globose clusters (occasionally slightly elongate), 1.3–2.0 cm long, oriented in several directions, the calyces 1.0–1.5 mm long, deeply 4-lobed, hairy. Pistillate inflorescences solitary in the leaf axils, dense, globose clusters 1.0–1.5 cm in diameter (but appearing larger because of the elongate stigmas), the calyces 2–3 mm long, deeply 4-lobed, the lobes obovate and clasping the ovary, densely hairy at their tips, style 2-branched, the stigmas unbranched, linear. Fruits fused into massive, compound, fleshy spherical masses, these 9–14 cm in overall diameter at maturity, the individual achenes enclosed in the enlarged, thickened calyces, which become fused and sunken into the enlarged receptacle, the surface of the multiple fruit yellowish green to green, with a convoluted, irregular network of shallow grooves and short, rounded ridges, and sometimes also scattered, short remains of the stigmas. 2n=56. May–June.

Probably ntroduced, scattered to common nearly throughout the state (native of Texas, Oklahoma, Arkansas, and perhaps portions of some adjacent states, introduced nearly throughout the remaining U.S., Canada). Bottomland forests, mesic upland forests, bottomland and upland prairies, banks of streams and rivers, marshes, and margins of sinkhole ponds; also fencerows, pastures, railroads, and roadsides.

Bois d’arc has played a key role in Missouri economies over many centuries. The species may have been native to southern Missouri or more likely was introduced in the state before the arrival of European explorers. Seeds and living plants were transported widely in pre-Columbian times, primarily because of the value of the wood for making bows (Moerman, 1998). It is the premier bow wood of North America. Bois d’arc bows were a valuable trade item, and they were found over much of eastern and central North America, often many hundreds of miles from the tribes that grew the trees and carved the bows. The hard, strong wood was also used for war clubs and tomahawks, as well as for ceremonial staffs. The inner bark and sapwood yield a yellow dye and rough cordage was made from the fibrous inner bark.

Early European settlers were quick to appreciate the quality of the wood and dyes, and the species also was widely planted as a street and shade tree. Bois d’arc became even more important when settlement reached the prairie regions of the state in the mid-nineteenth century. The scarcity of wood in the prairie districts made fencing impractical, and settlers turned to thorn hedges to keep their ploughed land safe from their stock. Bois d’arc quickly became the favorite hedge plant. The dense growth form and strong thorns of vigorous young plants made a hedge “pig tight, horse high, and bull strong,” (W. P. Webb [1931], quoting an anonymous writer of 1872) and it was widely planted in northern and western Missouri (and adjacent states) for this purpose. The hedges also protected land from prairie fires, which would often clear the vegetation from large areas of land in northern and western Missouri. As hedges matured, however, the large size of the plant and the extensive shallow root system took too much land away from the crops. Thorn hedges mostly were replaced by fences after the introduction of mass-produced barbed wire in the late 1870s, and the few hedges planted after this date were mostly roses (Rosa, Rosaceae), not bois d’arc. Bois d’arc continued to be planted as a shade tree and street tree, and to be used for a variety of purposes: the wood for railroad ties, fenceposts, wheel hubs and rims, and foundation blocks for buildings; the leaves were sometimes used for feeding silkworms; and the dye extracted from the bark continued to be important well into the twentieth century. Today, M. pomifera is still planted as a shade, street, and specimen tree. The species sometimes is considered to be invasive, forming thickets in upland prairies, especially in draws.

Lewis and Clark encountered the Osage orange growing at the St. Louis home of Pierre Chouteau, Thomas Jefferson’s local Agent of Indian Affairs (Earle and Reveal, 2003). Chouteau, a member of one of the city’s most influential families, handled trade negotiations with the Osage and other tribes for the Chouteau business empire. He advised and helped to outfit the Corps of Discovery for its historic voyage across the country. Chouteau provided cuttings of Maclura that Meriwether Lewis shipped back to Monticello on 16 March 1804 (W. W. Phillips, 2003). Jefferson not only grew the trees himself, but provided material to the Philadelphia nurseryman Bernard M’Mahon. Although apparently there were a few specimen trees already present in the eastern United States before this time, it was the plant material from St. Louis that formed the basis for much of the commercial cultivation of the species in that part of the country.