DAYtrip
Lilacs
at the U.S. National Arboretum By Mark L. DeBard
I visited the lilac collection at the U.S. National Arboretum (USNA) in Washington, DC, last year in late April. I was welcomed and assisted by Kevin Conrad, curator for woody landscape plants; Harlan Svoboda, herbarium curator; Susan Greeley, field manager for research plots; and Margaret Pooler, research leader. USNA has 334 lilacs in their possession, including most of the 10 natural and 15 hybrid species, but most of them are in private research areas. However, scores of lilacs are in their main public viewing area, easily accessible from either the New York Avenue or R Street entrances, seven days a week from 8am to 5pm. Because this is a research collection and not a featured garden collection, there is no public map or signage available to the lilac area nor for any individual lilac. But this won’t prevent you from enjoying the wide variety of early and common lilacs in this area (primarily S. vulgaris). It’s wonderful to enjoy 14
WASHINGTON GARDENER
MARCH 2022
the expected great lilac fragrance while viewing many of the unusual, unnamed test lilacs in the area. There is a free U.S. National Arboretum mobile app that can help you navigate the vast grounds of the Arboretum via a digital map. A search feature allows you to enter Latin or common names and locate specific plants on the grounds. Lilacs come in seven widely recognized colors: white, violet, blue, lilac, pink, magenta, and purple. Common lilacs can be bred to have double flowers as well. There are four types (or Series) of lilacs that don’t interbreed and bloom one right after the other, prolonging the blooming season for 8–10 weeks. An individual lilac will bloom 10–20 days, depending on the weather. Watch for the important feature of contrasting bud color, since the lilac bloom slowly moves from the base to the tip of the panicle. If you’re lucky, you’ll notice some of the few named cultivars present, such
as the multipetal blue ‘Wedgwood Blue’ or the deeply contrasting dark- and light-pink double ‘Sweetheart’ (pictured on page 15), or the soft-pink gradations of ‘Maiden’s Blush’. If you wander through the public research collection, look for one lilac whose florets have a “whirlybird” appearance—a trait that has become common and favored in the newer Eastern European cultivars, but is rare in North America. It will have a nicely saturated purple color. Perhaps you can find the deep-purple one that has a branch with a rare sport mutation of white buds and purple corolla giving rise to two-tone flowers. Or perhaps you’ll notice the violet one that has highly reflexed floret tips that point backward (most lilac petals are flat or cupped inward). I love the one with fabulous saturated magenta color and densely packed giant florets. Another great hybrid that has a nice contrast of dark-magenta buds with lighter-pink florets, but the
