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Though this is the smallest native elm, it has the largest leaves (up to nine inches long), with upper leaf surfaces extremely rough and sandpapery. Unlike most other elms, it also has reddish-hairy twigs and buds.

Other names: Red elm, moose elm.

Close relatives: American elm (U. americana); water-elm (Planera aquatica); hackberries (Celtis).

Lifestyle: Slippery elm grows faster than American elm but is not so opportunistic. This tree prefers moderately shaded woodlands. In drier upland forests, its presence indicates soils of high lime content. It sprouts vigorously when cut and may produce clones.

Most aspects of flowering are similar to those of the American elm, but the samara containing the seed may be almost an inch broader.

It has a more southerly distribution, reaching its northern limits in the northeastern states and southern Canada.

Associates: Slippery elm never grows in pure stands; scattered individuals mix with other deciduous species including white oak, sugar maple, American basswood, and others.

Spring, summer. Most plant and animal associates common to American elmincluding the disease organisms causing phloem necrosis and Dutch elm diseasealso frequent other native elms. Several insects, however, seem somewhat partial to slippery elm.

Spindle-shaped, hollow pouch galls on the leaves are produced by Gobaishia ulmifusus, the slippery elm gall aphid. The slippery elm midge (Dasyneura ulmi) produces swollen, bunchy growths, deforming leaf clusters.

An interesting long blotchlike mine is produced on upper leaf surfaces by the fly larva of the elm leafminer (Agromyza aristata) .

Look for blackish or orange-brown moths with white irregular lines on the forewings. These are white-lined bomolochas (Bomolocha abalienalis), whose caterpillars feed on the leaves.

Serpentine feeding trails beneath the leaf epidermis are signs of elm leafminers, which develop into tiny adult flies. As with many leaf mines, its distinctive shape identifies the insect that produced it.

Twig browsers include cottontail rabbits and white-tailed deer. One of the tree's common names, moose elm, derives from the moose's reputed fondness for the young shoots, but the tree is uncommon in moose range.

Porcupines relish the inner bark.

Page 83

Lore: This tree is mainly noted for its mucilaginous inner bark, a slimy, fibrous layer resembling licorice in taste. It has high food and medicinal value. In the spring, Native Americans peeled it from the tree in long strips, dried it, and ground it into pulp for use as a nutritious flour, a wound dressing, and a soothing tea for sore throat. A piece of this material also quenches thirst when chewed. Slippery elm inner bark was once popular as a pleasant "chew" and home remedy. It is still commercially available in lozenge or tonic form as a mild relief for raw throats. Pioneers used this fibrous layer for making tough thongs and lacings.

The freshly cut wood itself has a faint licorice odor. Though much heavier than American elm wood, this lumber is used for many of the same purposes (all elm wood is marketed as "soft elm").

Ferns, Wood (Dryopteris spp.)

Polypody family. Herbs in moist to dry woodlands. Their deeply cut leaves, kidney-shaped fruit covers (indusia), fruitdots (sori) attached or adjacent to veins on leaflet undersides, scaly stalks, and basketlike, clustered growth form are characteristic. Though this genus includes several wetland and dry cliff species, typical forest species are the marginal wood fern (D. marginalis), the spinulose or toothed wood fern (D. spinulosa), the male fern (D. filix-mas), and Goldie's fern (D. goldiana), the largest. Many other fern genera also inhabit woodlands and edges, but wood ferns are among the most common.

Other names: Shield ferns, evergreen ferns; varieties of D. spinulosa, especially, have many vernacular names. Close relatives: All ferns in the polypody family.

Lifestyle: These species all hybridize widely, their combined characters often making precise field identification difficult even for experts.

The basic reproductive scheme of these spore-bearing plants is an alternation of generations similar to that of clubmosses. Gametophytes, the actual sex forms of the plants, are so tiny and inconspicuous in the soil that they are seldom seen. The visible plant is the asexual sporophyte, or spore-producing, generation.

Though the four woodland species mentioned have somewhat different microhabitat preferences, all thrive in conditions of full or partial shade, all are perennial plants, and all are at least semievergreen.

D. marginalis, conspicuously green in winter, has a partially exposed rhizome resembling the trunk of a small palm tree, also suggesting a tree fern. Its large, marginal fruitdots are also distinctive, and the plant often shows a two-tone green contrast between older and younger fronds.

The many varieties of D. spinulosa are found in many habitats, but probably the most

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