The generic name is in honor of Lewis Théodore Hélie (1804—1867), a distinguished French physician.
1. [Helietta parvifolia] Benth.
Leaves 1½′—2′ long, with a stout slightly club-shaped petiole, at first puberulent, soon becoming glabrous, and oblong or narrow-obovate leaflets rounded or sometimes slightly emarginate at apex, gradually and regularly contracted at base, entire or slightly and remotely crenulate-serrate, yellow-green and lustrous above, paler below, conspicuously marked by black glandular dots, the terminal leaflet ½′—1½′ long, sometimes ½′ wide, and nearly twice as large as the others; persistent on the branches until early spring. Flowers appearing in April and May, on slender pedicels covered at first like the petioles and calyx with short dense pubescence, with minute acuminate early deciduous bracts, in dichotymously branched subsessile panicles on branchlets of the year from the axils of the upper leaves; petals 4, white, ovate, ⅛′ long, with scattered hairs on the outer surface, and thin scabrous margins, and four or five times longer than the 4 calyx-lobes; stamens 4; ovary 4-lobed, glandular-punctate like the slender style. Fruit ripening in October, oblong, ¼′—⅓′ long, with a rigid broad-ovate sometimes slightly falcate wing rounded at apex, ½′ long, and conspicuously reticulate-veined.
A slender tree, 20°—25° high, with a trunk 5′—6′ in diameter, rather erect branches forming a small irregular head, and slender pale branchlets covered with minute wart-like excrescences, slightly puberulous when they first appear, soon becoming glabrous, and marked during their second year by small inconspicuous leaf-scars; or a low shrub. Bark of the trunk about ⅛′ thick, covered with dark brown closely appressed scales separating in large irregular patches and leaving when they fall a smooth pale yellow surface. Wood hard, very heavy, close-grained, light orange-brown, with rather lighter colored sapwood.
Distribution. Often forming thickets of considerable extent and abundant near Rio Grande, Starr County, Texas; mesas south of the lower Rio Grande; of its largest size and tree-like in habit on the limestone ridges of the Sierra Madre of Nuevo Leon.
3. PTELEA L.
Small unarmed trees or shrubs, with smooth bitter bark, slender terete branchlets, without terminal buds, small depressed lateral buds covered with pale tomentum, and nearly inclosed by the narrow obcordate leaf-scars marked by the ends of 2 or 3 small fibro-vascular bundles, and thick fleshy acrid roots. Leaves alternate or rarely opposite, without stipules, long-petiolate, usually trifoliolate, the leaflets conduplicate in the bud, ovate or oblong, entire or crenulate-serrate, punctate with pellucid dots. Flowers polygamous, on slender bracteolate pedicels, in terminal or compound cymes, greenish white; calyx 4 or 5-parted; petals 4 or 5, hypogynous; stamens 3 or 4, alternate with and as long as the petals, hypogynous, much shorter in the pistillate flower with imperfect or rudimentary anthers; filaments subulate, more or less pilose, especially toward the base; anthers ovoid or cordate; pistil raised on a short gynophore, abortive and nearly sessile in the staminate flower; ovary compressed, 2—3-celled; style short; stigma 2—3-lobed; ovules superposed, amphitropous, the upper ovule only fertilized. Fruit a 2 or 3-celled broad-winged indehiscent samara surrounded by a reticulate wing or rarely wingless. Seed oblong, acute at apex, rounded at base, ascending; seed-coat smooth or slightly wrinkled, coriaceous; cotyledons ovate-oblong.
Ptelea is confined to the United States and Mexico, where four or five species are known; of these one is a small tree. The bark and foliage of Ptelea is bitter and strong-scented and possesses tonic properties.
The generic name is from πτελέα, a classical name of the Elm-tree.