Bloom Watch: The Azalea Collection

Bloom season for the Azalea collection is fast approaching, and Curator of the Arboretum’s National Native Azalea Collection Carson Ellis is keeping an eye on the plants as they begin to blossom. Read on for her weekly updates on what’s blooming in the garden.

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The recent cold snap has slowed the onset of spring, but scattered ephemerals throughout the Azalea Collection continue to bloom. Adding to the mix, I recently noticed that the white-flowered spikes of Pachysandra procumbens (Allegheny spurge; pictured left) have sprung up. These are easily observed on a frosty morning, when the foliage flops to the side. By the warmth of the afternoon, the attractive, mottled leaves of this native groundcover will right themselves again, hiding the flowers below. Look closely and you might notice that Pachysandra procumbens has monoecious flowers, meaning that the female and male parts are borne separately– inconspicuous female flowers are tucked into reddish bracts at the base of the inflorescence and male flowers are held at the top. One might expect petals to be the showiest parts of a flower, but Pachysandra procumbens has none. Instead, clusters of white stamens that draw the eye to this fragrant flower of the forest floor. 

The Arboretum is also home to several species of Hexastylis. Like the Pachysandra, these plants grow low to the ground and have flowers without petals. There are eleven species of Hexastylis known to grow in North Carolina, making our state the epicenter of Hexastylis diversity. Many of these species are visually similar and difficult to distinguish with leaves alone, making spring the best opportunity to identify them. In the Azalea Collection, Hexastylis rhombiformis (pictured right and below), the French Broad heartleaf, can be observed growing alongside Bent Creek under the shade of Kalmia latifolia and Rhododendron maximum. Look for the distinctive, heart-shaped leaves and gently move aside the leaf litter to find the vase-like flowers hidden underneath.

For those of you ready for showier floral displays, April is not far off and promises the beginning of our azalea bloom season. In the meantime, though, you can brush up on your native azaleas at a talk from Patrick Thompson, a conservation horticulturist and curator of the Davis Arboretum special collections. Patrick will be presenting on his work safeguarding the beauty and diversity of native azaleas in Alabama on March 27th at 4pm. Get more details and register here. 

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March 8, 2023

Things are getting busy in the Azalea Collection as crews of Arboretum horticulturists, looking forward to spring, lend a hand to remove brush and resurface the trails. The forest floor is also getting busy with expanses of Erythronium umbilicatum (pictured left), now beginning to open their cheery yellow blooms throughout the collection. These charming plants, named “trout lilies” in respect to their dappled foliage, are easily confused with E. americanum, but subtle differences, like E. umbillicatum’s lack of auricles on its tepals, dimpled capsule apex, and usually lavender-brown pollen, help distinguish the two. The trout lilies are joined by Stellaria pubera, Cardamine concatenata (pictured right), and several species of Viola. 

Notably, and surprisingly, the first Rhododendron in the collection has begun to bloom! The bright, purple flowers of Rhododendron chapmanii x mucronulatum (pictured below)  can be seen breaking bud beside the creek, a full month earlier than was reported in 2022. While this rhododendron hybrid does not have any native azaleas in its parentage, it does trace its heritage to Rhododendron chapmanii, an endangered Florida endemic. It makes a lovely addition to the landscape with petite evergreen foliage and is a welcome harbinger of spring blooms to come.

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March 2, 2023

Phenology studies the cyclical events of an ecosystem. In a landscape awakening for spring, this includes the unfurling of leaves and flowers, the emergence of overwintering insects like bees and butterflies, and the spring migration of birds returning to their breeding grounds. In overwintering animals, the end of dormancy might be signaled by warm temperatures, while flowering in plants can be influenced by multiple factors, including time spent in cool temperatures, onset of warmer temperatures, and day length. 

Already I’ve observed Xylocarpa virginica, eastern carpenter bees (pictured right), in the Azalea Collection. When bees and butterflies are coaxed out of dormancy in February and March we hope that they will find adequate resources and that a hard freeze won’t follow. As gardeners, we can support spring pollinators by planting diverse gardens with early-flowering species and by leaving spent plant material, like leaves, tall grasses, and fallen wood, in the landscape to provide shelter and nesting habitat. 

In the Azalea Collection, maples (Acer rubrum; pictured left) and spicebush (Lindera benzoin; pictured right) are in bloom. While these flowers are small, they are many, coloring the canopy and understory in a fine mist of red and gold. Below, the dappled foliage of trout lilies has begun to poke through the leaf litter and diminutive Cardamine flagellifera offer up bright blooms. If you’ve ever grown cool-season crops like kale, cabbage, broccoli, or brussel sprouts, you might notice that Cardamine, with their four-petaled flowers, resemble these common crops. In fact, they do all belong to the same plant family, Brassicaceae! I imagine that these Cardamine might taste spicy like their mustard relatives, but the Azalea Collection is not for eating (wish I could tell that to the deer and

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As the new Curator of the Arboretum’s National Native Azalea Collection, I started my work in October, just as much of the landscape was settling into dormancy; I have yet to see my first spring or summer in the Azalea Collection. Instead, I have been studying winter’s landscape: the placement of boulders on the hillside, the structure of the canopy, the tangles of Rhododendron maximumwith leaves that furl and unfurl as our days yo-yo between 70s and 20s. 

While gardens across Asheville are coming to life with daffodils, crocus, and even early cherry and magnolia trees bursting into bloom, the native plants growing in the Azalea Collection are more cautious to acknowledge February’s warm weather.

Keen eyes, though, might still spot a few early flowers: golden catkins dangling from American hazelnut (Corylus americana; pictured right) were first to unfurl, followed by the flower of Symplocarpus foetidus, the eastern skunk cabbage. Skunk cabbage (pictured right) is an unusual wetland plant, common in the northeast, but rare in Western North Carolina. Inconspicuous in color and stature, this plant can be hard to spot, but can be found along the margins of the Azalea Collection’s wetland.

Typical of the Araceae plant family, skunk cabbage have a type of flower called a spadix: small flowers borne on a fleshy stem and sheltered under the hood of a red- and green-speckled spathe. One of the earliest flowers to bloom, skunk cabbage have the curious ability to generate heat, allowing them to tolerate freezing temperatures and even melt snow. 

Already the still pools in the Azalea Collection are filled with masses of frog eggs and early butterflies, like Polygonia interrogationis, are fluttering across the sunny trails. Buds are swelling and greenery has begun to nose up through the leaf litter. Check back for updates as spring continues to unfold and be the first to know when our azaleas start to bloom!