Wafer Ash (Ptelea trifoliata) Quick facts:
Host plant to Giant, Eastern Tiger, and Two-tailed Swallowtails
Nectar plant to many butterflies and pollinators
Deciduous Perennial Tree
Native to East, South, Central, and Southwest US and Eastern Canada
Hardy in USDA zones 4-9
Full to partial sun
Best with well draining soil
White to greenish flowers bloom in spring
10-20 feet tall, can grow as a small tree or a bush
Member of Citrus family with distinctive seed pods
Love Swallowtails? Plant a Wafer Ash!
The lovely Hoptree or Wafer Ash is a small ornamental tree or shrub that attracts Swallowtails in a big way. It’s hardy from zones 4-9, and is the Swallowtail’s northernmost host plant. Two weeks of 2-3-inch fragrant white blossom clusters in the late spring/early summer provide a nectar source for pollinators and butterflies including the Easter Comma. Pro tip: if you notice what looks like bird droppings on its leaves, look more closely–they may be Giant Swallowtail caterpillars!
Ptelea trifoliata Motto: Bloom Where You’re Planted.
The Ptelea trifoliata grows most robustly as an understory tree in partial shade, enjoying moist, well-drained soil that is alkaline or acidic. It tolerates clay, loam, or sand. You can frequently find it growing wild at the edge of a forest. However, it can also adapt happily to full sun, where it tends to mature into a bush rather than a tree. It’s one of a handful of small trees that can thrive in deep shade, but will sport more blooms in ample sunlight. Rocky, dry areas? No problem for the Wafer Ash–this tough ornamental is a fabulous pick for unirrigated gardens and gravelly locales. No space? Plant it in a large container and watch it flourish! Once mature, it’s drought-tolerant.
It is also highly resistant to hungry deer and rabbits that may be lurking about. It’s not prone to pest infestation or disease. Is it any wonder the Wafer Ash was given the Royal Horticultural Society’s Award of Garden Merit?
Plant after frost danger passes with a spacing of at least 12 feet, as the trees will grow from 10 to 25 feet high. If grown as a shrub, it can attain heights of more than 8 feet. Expect a spread of 8-15 feet. A group planting can form a lovely formal hedge or screen. Leaves turn gold in autumn, and seed pods cling to branches for winter’s duration.
Samaras. They Aren’t a Girl Scout Cookie.
The samara is the thin, winged, wafer-like seed pod that gives the Wafer Ash its name. Not quite an inch long, they dry to a distinctive light toast color. They ripen in late August and their presence provides a wonderful opportunity to enjoy the sight of birds relishing them as a winter snack. They have been used to replace hops in beer (hence the name, Hopwood tree), but they are an ingredient of last resort due to their extremely bitter taste.
The Attractive Aromatic.
Every bit of this ornamental is fragrant–flowers have an orange blossom scent, and crushed leaves release a citrus aroma. The overall shape is pleasingly rounded. Since the Wafer Ash is not a true ash tree, threats like the emerald ash borer do not affect this tree. Bottom line–if you want to attract Swallowtails, the Wafer Ash is a great way to go!