Thursday, August 12, 2010

Hop Tree


A small genus with only 15 species of trees or shrubs native to North America and Mexico.
Prefers full to partial sun ( partial sun is best in climates with hot summers, it can tolerate full shade but may be sparse ).
Propagation is from seed or layers. The ripe seed once collected during autumn should be cold stratified for 3 months once dried. The seed should be soaked in water for 24 hours before sowing at 0.7 inches deep. Cultivars can be easily propagated from softwood cuttings taken during summer.

Ptelea baldwinii ( Baldwins Hoptree )
Also called Ptelea trifolia var mollis and Ptelea angustifolia. A large shrub to 15 feet that is native to the southwest U.S. ( from southern Utah and Colorado; south into Mexico ). It sometimes becomes a tree, especially if pruned as such. Some records include: 20 years - 12 feet ( avg. ); largest on record is 27 x 20 feet with a trunk diameter of 15 inches.
The foliage is trifoliate with all 3 leaflets the same size to 2.5 inches in length. The lance-shaped to oblanceolate leaflets are narrower than that of Ptelea trifoliata. The leaves are covered in fine hairs at first and turn to bright green in summer then to bright yellow during autumn.
The pale green flowers are followed by winged fruit that is up to 0.7 inches in width.
The bark is whitish.
Hardy zones 5 to 10

Ptelea crenulata ( California Hop Tree )
A large shrub to 15 feet that is native to California ( from Siskiyou Co. in the extreme north to mountains near Los Angeles ). It can be trained to grow as a small tree, the largest on record is 22 x 13 feet with a trunk diameter of 1.5 feet.
The leaves are trifoliate with 3 finely-toothed leaflets up to 5.5 ( rarely over 3 ) inches in length. The foliage is bright green and borne on a leafstalk up to 3 inches long.
The bark is smooth.
Hardy zones 7 to 9 in full sun on just about any well drained soil.

* photo taken by Anthony Baniaga

Ptelea trifoliata ( Common Hop Tree )
A moderate growing, small tree with a dense, bushy, rounded crown, reaching up to 20 feet or more, that is native to the central U.S. ( from southeast Nebraska to central Iowa to southern Wisconsin to Muskegon, Michigan to Sarnia, Ontario to Tillsonburg, Ontario to western New York State to Massachussetts, south to Mexico to northern Florida ). It is endangered in its native range in Ontario, Canada where it is mostly found on beach sand and limestone on the north shore of Lake Erie. Shoreline development has destroyed many native populations there...Point Pelee, Pelee Island and near Port Colborne are the only sizable remaining wild populations. In Essex County, it once ranged as far west as Colchester and was very abundant at Point Pelee, the Lake Erie islands as well as sandy areas on the Ohio shore. It was once much more common throughout the north shore of Lake Erie and was also found inland at Wapole Island, Thamesville and near Niagara-on-the-Lake. It is also endangered in Wisconsin, New York State and Pennsylvania. It is usually found on floodplains and open woods in the wild. Some records include: fastest recorded growth rate - 10 feet ( stump sprout ); largest on record - 50 x 32 feet with a trunk diameter of 1.5 feet. A tree at Cedar Point, Ohio was measured as having an 11 inch truck diameter during the 1890s. It makes a great screen or patio tree. Common Hop Tree is an important larval host for the Eastern Tiger Swallowtail & Giant Swallowtail Butterflies.
The leaves are composed of 3 oval, mostly smooth-margined leaflets with the central one, up to 4 or rarely to 6 inches in length being the largest. The aromatic foliage is semi-glossy and mid-green above and paler below. The leaves turn to bright yellow during autumn.
The very fragrant, greenish-white, starry flowers, up to 0.5 inches wide, are borne in terminal clusters in early summer.
The flowers are fragrant and smell like orange blossom.
They are followed by beige color, papery winged fruit up to an inch wide that persists late into fall. Hop Tree is structurally tough and sturdy.
The twigs are stout and aromatic.
The gray bark is thin and warty.
Hardy zones 2 to 8 on fertile, well drained soil. It is hardy far north of its native range and even survives as far north as Saskatoon, SK and Lenningrad, Russia.
Tolerant of alkaline and sandy soil, it is sometimes found on sandy dunes in the wild.

* photos taken on August 3 2010 @ University of Guelph Arboretum, Ontario

* photos taken on August 5 2010 @ Woodlands Arboretum, Clinton, Ontario

* photo taken on May 27 2017 @ Meadowlark Botanical Gardens, Vienna, VA

* photos taken on Jul 18 2017 @ Dominion Arboretum, Ottawa, ON

* photo taken by W.D. Brush, hosted by the USDA-NRCS PLANTS Database

* photo taken by G.B. Sudworth, hosted by the USDA-NRCS PLANTS Database

* historic archive photos

Foliage is bright yellow at first, later turning to yellow-green. It usually comes true from seed.
It is less hardy north of zone 5 than the species, suffering occasional winter dieback at Ottawa, Ontario ( zone 4b ) therefore not reaching tree size there despite Ptelea trifoliata itself being fully hardy.

Very attractive bright blue-green foliage

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