Early-blooming, large-flowered shrub of woodlands and edge habitats; a remarkable understory shrub, beautiful in all seasons; ranges from Nova Scotia west to Michigan, south to the mountains of North Carolina, Tennessee and Georgia; prefers cool, moist soil and shade.
By Pamela Johnson
Maine has seven viburnum species (and four subspecies) that comprise an important portion of our forests’ understory and woodland edges. Generally the viburnums are six to eight feet tall with loose branching and slender stems; Viburnum acerifolium is the modest exception which rarely exceeds three or four feet in height. Most viburnum species form their own clonal thickets and this expansive, sometimes tangled habit gives rise to one viburnum’s common name, hobblebush.
Viburnum lantanoides, hobblebush (also known as moosebush, witch-withy, witch-hobble, witch-tangle and tangle legs) can grow more than ten feet tall, and often at least as wide, in its sprawling, errant, fashion. Branches extend outward, arch and descend, re-rooting where they touch the ground, forming a small copse. This lissome habit is most evident in winter when the hobblebush is leafless and the shrub’s structure can be traced. What appears to be a solitary shrub is usually an aggregate of clonal offspring called ramets.
Hobblebush is easy to identify at any time of the year. It is one of the earliest shrubs to flower in spring; buds open about the same time as red maples (Acer rubrum) flower and the poplars (Populus species) are shedding their cottony catkins. The large, flat, white flower clusters anticipate and overlap the blossoms of shadbush (Amelanchier species), the wild cherries (chokecherry, Prunus virginiana, and pin cherry, P. pensylvanica), and wild plum (P. americanus). Hobblebush blooms can persist several weeks at least, from early May, sometimes into early June.
Hobblebush flowers are large creamy saucers, conspicuous enough to attract pollinators in the shaded situations the shrubs prefer. The hobblebush’s inflorescence, an umbel, a cyme, or an umbel-like compound corymb (depending upon which botanist one consults), has a circumference of large, five-petalled, sterile florets surrounding a fist-sized cluster of small fertile flowers. The showy outer flowers are thought to guide insects to the inner rewards, but pollination of the hobblebush seems not to be well studied. Suggested pollinators are bees (genus Bombus, Nomada maculata, and Andrenidae), wasps (Hymenoptera), flies (Syrphidae and Muscidae),; also butterflies and moths (Lepidoptera). Since the flowers have a faint musty odor, beetles (Coleoptera, specifically the Cerambycidae) are also candidates for pollinators. The flowers do not produce much nectar, and it is evanescent. Even so, ruby-throated hummingbirds (Archilochus colubris) and the hummingbird clearwing moth (Hemaris thysbe) visit hobblebush flowers. The hummingbird clearwing is a beguiling creature who hovers in a blur of wingbeats, and sips nectar like its namesake; the larva is a hornworm caterpillar who feeds on viburnum leaves. Spring azures (Celastrina ladon species complex) among our earliest butterflies, are also hobblebush flower feeders.
It seems a light has been extinguished in the forest when hobblebushes drop their petals, but the foliar display that follows is spectacular. Young leaves, demure and madder-brown, frame the opening blossoms. Their nascent color is a deeper shade of the branch color, but the leaves quickly mature into dessert plates of deep green, a perfect scaffold for the flowers and ensuing fruit. Here is Michael Dirr’s description of hobblebush leaves from his monograph on viburnums:
. . . broad-ovate to suborbicular, 4-8” long, nearly as wide, short acuminate, cordate, irregularly denticulate, stellate pubescent above at first, later glabrous, more densely pubescent beneath, chiefly on veins. Petiole is 1-2 ½“ long and scurfy.”[i]
The string of terminology is reminiscent of the logorrheal, pre-Linnaean classification of viburnum, Viburnum folliis cordatis serratis venosis subtus tomentosis (which makes one grateful for Latin binomials). Dirr is precise of course, given the variations in hobblebush leaves-size, shape, dentition, and changes through development. “Scurfy”, which sounds like a slur is a legitimate botanical adjective meaning “beset with small scales, providing a rough, irregular texture.”[ii]
The size and breadth of hobblebush’s somewhat heart-shaped leaves makes the shrub seem more leafy than it is. And the reaching branches appear to be delivering huge green valentines to their near neighbors.
Fruit is well-formed by mid-summer. The drupes, each containing a large, single seed, are briefly green, then red, turning purple or blue-black at maturity. The leaves begin to tint burgundy, sometimes orange or yellow, as the summer wanes. Bare winter branches look fawn-brown and radiant against a background of dark conifers in deepest shade; they stretch and yearn to embrace whatever light can be found in what Thoreau called “the under-woods”.[iii]
Hobblebush’s winter buds make the greatest display. There are no protective bud scales. Miniature pairs of leaves, exquisitely clasped together, can be seen clearly. Some leaf pairs enfold a tiny, but perfectly formed flower bud, ready to grow in the earliest spring warmth.
Deer, moose, snowshoe hares- who can easily nip the nether branches- browse hobblebush in winter. The fruit is low in fat so it is an ancillary choice for songbirds; grouse eat the fruit and twigs. Eastern chipmunks and red squirrels harvest hobblebush seeds. Henry David Thoreau wrote, on September 17 1853, in his Chesuncook journal:
The conspicuous berry-bearing bushes and trees along the shore were the red osiers, with its whitish fruit, hobble-bush, mountain-ash, tree-cranberry, choke-cherry, now ripe, alternate cornel, and naked viburnum…I ate the fruit of the last, and also of the hobble-bush, but found them rather insipid and seedy.[iv]
In the 1940’s a European beetle, Pyrrhalta viburni, arrived in Canada. It descended into the Great Lakes region in the mid-1980’s, and was discovered in Maine in 1994. The beetles’ impact upon many native viburnums was immediately obvious, and devastating: whole swaths of understory were repeatedly defoliated by the beetles’ larvae, and many shrubs died within two or three years. The infestation has ebbed and flowed in the past decade, and because viburnum beetles eggs require a period of cold to gestate, New England and northern New York have seen the worst damage. For the past few years the insects have been, anecdotally, less destructive. Throughout the infestation, Viburnum lantanoides has shown resistance to the beetles’ rampage, perhaps because of its somewhat fuzzy leaf surfaces, or those scurfy petioles (egg-laying is concentrated in leaf stems and the tenderest twig growth). Concern about the viburnum leaf beetle incursion seems to have abated recently, perhaps because North American viburnums never comprised a hugely lucrative segment of the nursery trade, and the more popular Asian viburnums species were weakened, but usually not killed by the beetles. It may also be true that some predators, birds or insects, have developed a taste for the adult beetles or their voracious larvae- hard to imagine given the stench of the latter while feeding. Warmer winter temperatures and shorter winters may reduce egg viability. Egg masses are easy to spot on the susceptible viburnums and small infestations can be pruned out by hand. Henry Kock, in Growing Trees from Seed, posits that even the worst insect assaults (like the gypsy moth’s, Lymantia dispar) are cyclical, and that patience and biodiversity are the antidotes. Gardeners often do not take the long view when a favorite shrub has lost all its leaves. Sidestepping further discussion, let it be said that Viburnum lantanoides, when planted appropriately, is highly beetle-resistant, long-lived and lovely in the landscape or garden.
Seeds are ripe when the fruit turns from red to purple or blue-black; germination of fresh seed may take two years through alternating periods of warm, moist, stratification, to cold, then warm again. Some experienced plant propagators have success with tricking the seeds into germinating a year earlier by collecting the fruits when they are red, painstakingly removing the flesh, and planting them immediately (see William Cullina’s Growing and Propagating Native Trees, Shrubs and Vines). Either way, this plant deserves a place in shady landscapes and should be more widely propagated by nurseries.
[i] Dirr, Michael A. 2007. Viburnums. Portland, Oregon: Timber Press. p.111.
[ii] Haines, Arthur. 2011. Flora Novae Angliae. New Haven: Yale University Press. p.xxx.
[iii] Thoreau, Henry David. 2009. The Maine Woods. edited by Jeffrey S. Cramer. New Haven: Yale University Press. p.282
[iv] Ibid, p. 286