Ptelea trifoliata, commonly known as common hoptree, wafer ash, stinking ash, is a species of flowering plant in the citrus family (Rutaceae). It is native to North America, where it is found in Canada, Mexico, and the United States. It is a deciduous shrub or tree, with alternate, trifoliate leaves.
Description
Ptelea trifoliata is a small tree, or often a shrub of a few spreading stems, growing to around tall with a broad crown. The bark is reddish brown to gray brown, with short horizontal lenticels (warty corky ridges), becoming slightly scaly, The plant has an unpleasant odor and bitter taste. Branchlets are dark reddish brown, shining, covered with small excrescences. The twigs are slender to moderately stout, brown with deep U-shaped leaf scars, and with short, light brown, fuzzy buds. It has thick fleshy roots. some botanists treat the various hoptrees as a group of four or more closely related species:
- P. trifoliata subsp. trifoliata – common hoptree or eastern hoptree; eastern Canada & United States (U.S.), central U.S.
- P. trifoliata subsp. trifoliata var. trifoliata – eastern Canada & (U.S.), central U.S.
- P. trifoliata subsp trifoliata var. mollis <small>Torr. & A. Gray</small> – eastern and central U.S.
- P. trifoliata subsp. angustifolia <small>(Benth.) V.L.Bailey</small> – south-central U.S.
- P. trifoliata subsp. angustifolia var. angustifolia <small>(Benth.) M.E.Jones</small> (P. angustifolia, P. lutescens) – narrowleaf hoptree; south-central U.S.
- P. trifoliata subsp. angustifolia var. persicifolia <small>(Greene) V.L.Bailey</small> – south-central U.S.
- P. trifoliata subsp. pallida <small>(Greene) V.L.Bailey</small> – pallid hoptree, south-central and southwest U.S.
- P. trifoliata subsp. pallida var. pallida <small>(Greene) V.L.Bailey</small> – southwest U.S.
- P. trifoliata subsp. pallida var. cognata <small>(Greene) Kearney & Peebles</small> – southwest U.S.
- P. trifoliata subsp. pallida var. confinis <small>(Greene) V.L.Bailey</small> – south-central and southwest U.S.
- P. trifoliata subsp. pallida var. lutescens – southwest U.S.
- P. trifoliata subsp. polyadenia <small>(Greene) V.L.Bailey</small> – pallid hoptree, south-central and southwest U.S.
- P. trifoliata var. baldwinii <small>(Torr. & A.Gray) D.B.Ward</small> (P. baldwinii)
The specific epithet "trifoliata" refers to the three-parted compound leaf.
Other common names for this shrub include stinking prairie bush, Carolina shrub-trefoil, tree-trefoil, swamp dogwood, ague bark, paleleaf hoptree, prairie-grub, prickaway-anise, quinine tree, sang-tree, water-ash, western hoptree, wingseed, and woolly hoptree.
Distribution and habitat
Ptelea trifoliata is native to North America, where its northern limits are in Ontario and Quebec, Canada. It is native through much of the eastern and southwestern United States, although it is absent from some areas of the Upper Midwest and is rare in much of New England. Its southern limits are in Mexico.
It has a wide-ranging natural habitat. In the Southeastern United States it is most often found in rocky forests, in both moist and dry soil, often associated with calcareous or mafic substrates. In the Midwest, habitats include forests, savannas, prairies, glades, and sand dunes. In Arizona it is common in canyons.
Ecology
Larva of the giant swallowtail butterfly Papilio cresphontes feed on the leaves. Treehoppers of the genus Enchenopa infest the branches, laying white-frothy masses of eggs on the branch undersides.
Numerous cultivars have been developed for ornamental use in parks and gardens. The cultivar 'Aurea' with golden leaves has gained the Royal Horticultural Society's Award of Garden Merit.
German immigrants to Texas in the 19th century used its seeds in place of hops in the beer-making process, lending the species its common name.