Part 1

Clair A. Brown Harold E. Grelen

IDENTIFYING HARDWOODS GROWING ON PINE SITES

Southern Forest Experiment Station U.S. Department of Agriculture, Forest Service General Technical Report SO-15

Acknowledgments

The authors thank Bryan A. Jowers, Glendale, California, for the excellent winter silhouettes. For help in obtaining specimens or photographs of species not easily accessible to us, we thank the following: Roger W. Barbour, University of Kentucky; William Harlow, College of Environmental Science and Forestry, State University of New York; Richard Johnson, Caroline Dormon Nature Preserve; Betty E. Lemon, University of Southwestern Louisiana; R. Dale Thomas, Northeast Louisiana University; and Lino Della-Bianca and Edwin R. Lawson of the U.S. Forest Service.

Summary

This publication illustrates and describes 26 hardwood species or varieties, including 16 oaks and hickories, with photographs of leaves, bark, buds, flowers, and fruits. Line drawings feature the winter silhouette of each species and a key is included to assist in identification.

US. Department of Agriculture Forest Service General Technical Report SO-15

Identifying Hardwoods Growing On Pine Sites

CLAIR A. BROWN Professor Emeritus, Department of Botany Louisiana State University Baton Rouge, Louisiana

HAROLD E. GRELEN Principal Range Scientist Southern Forest Experiment Station Forest Service—USDA Pineville, Louisiana

1977

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402

Contents

Page Overview of Southern Hardwoods 1 Key to Hardwoods 6 Species Described and Illustrated Mockernut hickory 10 Pignut hickory 12 Shagbark hickory 14 Bitternut hickory 16 Southern red oak 18 Cherrybark oak 20 Black oak 22 Scarlet oak 24 Northern red oak 26 Shumard oak 28 Blackjack oak 30 Laurel oak 32 Water oak 34 White oak 36 Post oak 38 Chestnut oak 40 Winged elm 42 American elm 44 Sugarberry 46 Yellow-poplar 48 Sweetbay 50 Sweetgum 52 Red maple 54 Black tupelo 56 White ash 58 Green ash 60 Selected References 63 Glossary 65 Index 69

Overview of Southern Hardwoods

Throughout the South some 49 billion cubic feet of small, low-quality hardwoods are growing on southern pine sites (Staff, For. Resour. Res. Work Unit 1976). This material is usually wasted; if the site is prepared for regeneration to pine, the hardwoods there are destroyed. Research is underway to find economical methods of harvesting and utilizing these hardwoods. The descriptions, key, and illustrations in this book should help wood utilization researchers, especially those new to the South, to identify the most prevalent hardwood species on southern pine sites (Table 1).

Table 1.—Important hardwoods on southern pine sites, ranked according to percentage of total hardwood volume

Percentages were derived from Staff, For. Resour. Res. Work Unit (1976).

Nomenclature used herein follows Little (1953).

Species Percent

Sweetgum Liquidambar styraciflua L. 13.2 White oak Quercus alba L. 12.3 Hickory Carya spp. 8.5 Southern red oak Quercus falcata Michx. 8.1 Post oak Quercus stellata Wangenh. 7.0 Yellow-poplar Liriodendron tulipifera L. 7.0 Black tupelo Nyssa sylvatica Marsh. 5.5 Water oak Quercus nigra L. 4.7 Black oak Quercus velutina Lam. 4.0 Scarlet oak Quercus coccinea Muenchh. 3.6 Red maple Acer rubrum L. 3.6 Chestnut oak Quercus prinus L. 2.9 Northern red oak Quercus rubra L. 2.4 Laurel oak Quercus laurifolia Michx. 1.4 Elm Ulmus spp. 1.4 Cherrybark oak Quercus falcata var. pagodaefolia Ell. 1.2 Ash Fraxinus spp. .9 Sweetbay Magnolia virginiana L. .6 Shumard oak Quercus shumardii Buckl. .2 Hackberry Celtis spp. .1 Other hardwoods including blackjack oak (Quercus 11.4 marilandica Muenchh.) Total hardwoods 100.0

Hickories have alternate compound leaves with 5 to 13 leaflets. They are monoecious; that is, the stamens and pistil are borne in separate flowers on the same plant. Flowers generally develop after the leaves are three-fourths to full grown. Staminate flowers are in catkins, which occur on last year’s wood and usually have three branches. The stalkless pistillate flowers are in several-flowered spikes at the apex of the current season’s growth. Catkins last from 10 days to 3 weeks and are usually not useful in distinguishing the species. The fruit, however, is widely used for identification. The husk may be very thin (about 1 mm), moderately thick (3 to 5 mm), or very thick (more than 5 mm). Similarly, the shell may be thin, moderately thick, or very thick. The meat varies from sweet to bitter. Upon drying, the husk usually separates along sutures and frees the nut. In some species the husk partly splits at the sutures but still encloses the nut when it falls. Such nuts are usually sterile, because the meat is seldom filled out.

For identification purposes use nuts from the ground with caution; if more than one species grows in the vicinity, the fruits could be mixed. Also some trees shed defective or sterile fruits early, and these fruits are often different in shape and size from typical fruit.

Hickories are generally divided into true hickories, which have overlapping (imbricate) bud scales, and pecan hickories, which have valvate bud scales. True hickories are divided into those with tight bark and those with loose bark. Mockernut Hickory, Carya tomentosa Nutt., a tight bark species, has very pubescent leaves, large buds, and a thick husk over a large nut. Pignut Hickory, C. glabra (Mill.) Sweet, also a tight bark hickory, has three to nine glabrous leaflets and a tardily dehiscing husk about 3 mm thick. Shagbark Hickory, C. ovata (Mill.) K. Koch, is one of the few species with bark in thin, loose plates. It has small buds and usually has five leaflets. Bitternut Hickory, C. cordiformis (Wangenh.) K. Koch, belongs to the pecan hickory group and has yellow buds with valvate scales. It also has tight bark, thin four-winged husks, thin shells, and bitter meat.

Oaks are also monoecious, and staminate flowers are in drooping catkins, which consist of a central, flexible axis with sessile, apetalous and pubescent flowers. They are most abundant on the developing new twigs. Although catkins vary among oaks, they are usually not used as distinguishing characteristics because they last only 2 to 3 weeks. Pistillate flowers occur on wood of the previous season and in leaf axils of twigs. In red oaks, however, pistillate flowers on current twigs do not mature until the second fall.

The fruit, a nut or acorn, consists of the seed enclosed in a shell. The nut is seated in a cup consisting of many scales. At maturity nuts are shed from the tree by shrinkage of the cup (dehydration). Considerable variation in mature acorn size occurs among trees of a species, notably in water oak, willow oak, and white oak.

Differences in foliage within a species also complicate identification. Apparently because lower leaves receive less sunlight they differ in size and appearance from those in the middle or upper crown. Most taxonomists prefer a specimen from the upper half of the crown because they consider leaves from this area typical for the species. To get such specimens easily, use a tree pruner and take leaves from at least 20 to 30 feet off the ground or collect them from freshly felled trees. Moreover, foliage of seedlings and small saplings often differs from that of mature trees, and spring and summer growth flushes on the same branch often appear markedly different. This seasonal variation has been noted for many oaks, including laurel, post, blackjack, and especially water oak. For example, by late March or April, water oak leaves reach their normal size and shape—obovate with a wavy apex; the second flush of growth, which starts in late April or May, produces lobed leaves.