Ptelea Trifoliata or Hop Tree
The Greek word ptelea was originally applied to the elm because of its winged seeds (the word ptoein means to fly). The genus is widespread in North America and Mexico and includes some 60 species. They are deciduous shrubs or trees. The leaves are opposite, usually three-foliate, occasionally five-foliate, made up of transparent-dotted leaflets with entire or toothed margins. Thehave four to five sepals and are borne in terminal clusters (cymes) on short, lateral branchlets. They are insignificant and coloured whitish-green. The elm-like fruits are striking, consisting of a hard samara encircled by a prominently veined border.
The hop tree is a shrub growing to a height of 6m (20 ft) and flowering in June. It was introduced into Europe in 1724. There are several varieties, some of which are considered to be separate species. Most important is Ptelea trifoliata mollis with the young shoots and leaves hairy on the underside; P. t. pentaphylla with three three- to five-foliate leaves; puhescens with leaves hairy beneath and mat green above; fastigiata of pyramidal form, and aurea with yellow foliage.
The hop tree is readily propagated by means of seeds which are sown in the autumn or stratified and sown in spring. It has no specialrequirements and will grow even in dry and poor soils. It is most effective in large gardens and parks, on roadsides and in city streets. It is planted as a solitary specimen, in groups or in rows.