1. Leitneria floridana Chapm. (corkwood)

L. pilosa J.A. Schrad. & W.R. Graves

L. pilosa ssp. ozarkana J.A. Schrad. & W.R. Graves

Pl. 445 g, h; Map 2611

Plants shrubs or occasionally small trees, usually dioecious, suckering from creeping rootstocks and forming dense thickets. Trunks 1.0–4.0(–7.5) m tall, the bark smooth, gray to dark reddish brown, with prominent lenticels. Twigs 3–4 mm thick, densely grayish-hairy, the winter buds more or less triangular, with several scales, densely white-hairy. Leaves with the petioles 2.0–5.5 cm long. Leaf blades 6–23 cm long, 2–10 cm wide, simple and unlobed, lanceolate to narrowly elliptic, occasionally narrowly ovate or oblanceolate, somewhat leathery, angled or tapered to less commonly rounded at the base, narrowed or tapered to a bluntly or sharply pointed (rarely rounded) tip, the margins entire, the upper surface green, sparsely to densely hairy, the undersurface pale green or light yellow, densely felty-hairy, the veins strongly raised. Inflorescences dense, ascending catkins from second-year twigs, 1–4 cm long at flowering, the pistillate catkins shorter and narrower than the staminate ones. Flowers apparently actinomorphic. Staminate flowers difficult to differentiate in the catkins, with small groups of flowers in dense clusters, each cluster subtended by a small hairy ovate-triangular bract, the calyces rudimentary or absent, the corollas absent. Stamens 3 to apparently 10–12(–15), the filaments short. Pistillate flowers each subtended by a small, ovate-triangular, hairy bract and 2 minute scalelike bractlets, the calyces of (3)4(–8) minute sepals, the corollas and staminodes absent. Pistils 1-locular, finely hairy, the placentation lateral. Style 1, linear, often somewhat twisted, dark red, not persistent, the stigmatic area lateral in a minute groove toward the tip. Fruits drupes, 15–20 mm long, 6–7 mm wide, narrowly ellipsoid to narrowly obovoid, slightly flattened, green becoming olive green to greenish brown with age. 2n=32. February–April.

Uncommon in the Mississippi Lowlands Division (southeastern United States, from Missouri south to Florida and Texas). Bottomland forests, swamps, and rarely margins of ponds and lakes; also ditches and wet roadsides.

Schrader and Graves (2011) recently divided L. floridana into three taxa with disjunct geographic ranges. According to their taxonomy, only plants native to northern Florida and southern Georgia are L. floridana, whereas material from Missouri and Arkansas is L. pilosa ssp. ozarkana (var. pilosa is found in eastern Texas). Plants from the western portion of the range were indicated by these authors to differ from the populations in Florida in their smaller leaves and at least the undersurface of the leaf blades relatively densely hairy. However, These conclusions were based on the study of only seven populations, and the authors cited no specimens except for their own collections. Examination of herbarium material from a wider range of sites indicates that these plants are much more variable morphologically than the keys and descriptions provided by Schrader and Graves (2011) indicate. Plants from the three geographical areas cannot be distinguished consistently using the characters given in their paper. Separation of Missouri material from L. floridana cannot be justified unless reliable characters can be discovered and confirmed through study of a wide spectrum of specimens from throughout the range of the genus.

Corkwood formerly formed dense thickets in bottomlands of the Mississippi Lowlands Division, although in gardens it flourishes much farther to the north in well-drained soils. Much of its former habitat has been eliminated by clearing and draining of the Bootheel region and today the species survives mainly along ditches, which are prone to periodic dredging and spraying of herbicides. Because of habitat destruction throughout its range, in recent years there have been conservation concerns about the decline of this unusual plant.

The wood of corkwood is soft and is the lightest wood of any species native to North America. It has been used locally as a cork substitute, especially for fishing floats. The species is sometimes cultivated as a specimen plant. It can form dense colonies and does well in gardens, even far to the north of its native range (Channell and Wood, 1962). In mixed plantings, over time there is a tendency for staminate clones to outcompete pistillate ones.