Twenty-four million years ago, the forests that covered the southeastern United States were remarkably similar to those still found in portions of the same area today. Pockets of vegetation tucked away in Appalachian valleys and on the Ozark Plateau were saved from the repeated ravages of glaciation. As each onslaught of glaciers retreated, these floral repositories recolonized the landscape, but dominant plant species lost their competitive advantage in the resultant climatic and geological changes and lack of genetic diversity. In evolutionary terms, Neviusia alabamensis, a plant known today as Alabama snow wreath, was already in serious trouble when it was discovered in 1857.
During a botanical excursion with Professor W. S. Wyman along the cliffs overlooking Alabama's Black Warrior River that year, Dr. Reuben Denton Nevius observed and collected an unfamiliar shrub. Nevius sent a description to Professor Asa Gray of Cambridge Botanic Garden. The plant proved new to science, and Gray suggested the name Neviusia—which the discoverer humbly accepted. (It later came to light that Nevius had been less than candid about his discovery; in fact, it had been Wyman who first observed it.)
This obscure genus has no close American relative within its family, the Rosaceae. The fact that its flowers are without petals sets it apart within a family known for, on this continent at least, the presence of a corolla. Botanists consider N. alabamensis a relic species with a greatly reduced geographical range, rather than a true endemic of recent origin. Within the rose family, Neviusia is placed in the tribe Kerriae, which it shares with two Asiatic genera, each with only a single species: Kerria japonica and Rhodotypos scandens.
Botanically interesting and exceedingly rare in the wild, N. alabamensis is undeservedly obscure in American horticulture today. Few deciduous ornamental shrubs thrive in shade as Neviusia does, and its beauty in full blossom is quite remarkable. Profuse, snow-white blossoms emerge with soft green foliage in April and May. These feathery flowers and the shrub's elegant arching habit suggest an imagined hybrid of Fothergilla major and Spiraea vanhouttei.
Neviusia benefits from a rich, loamy, well-drained soil, and a moderate amount of water during the summer. A thorough pruning directly after flowering will promote more profuse blossoming the following year, although such action sacrifices the attractive, fleshy postbloom calyces. Neviusia is not browsed by deer and can be maintained as a sensational informal hedge.
Neviusia alabamensis grows as a suckering shrub up to six feet in height and, under ideal conditions, can produce dense thickets up to several yards across. This suckering habit may be the only means of replication the species employs. The reproductive biology of the native populations is little understood. In the few years of observation by botanists, no recently germinated seedlings have been found, making some suspect that many of the known populations are in actuality each one very large plant.
For nearly one hundred years, the two populations that Nevius and Wyman discovered in 1857 were the only places the plant was known to exist. Mining operations at the turn of the century destroyed one of these. A total of 16 additional groups have since been discovered in Alabama, Arkansas, Tennessee, Mississippi, and Georgia. In 1992, another species of Neviusia was discovered in northern California. It was named Neviusia cliftonii after its codiscoverer, Glen Clifton. It has an equally restricted natural distribution, growing only on limestone embankments adjacent to running water on the eastern side of Lake Shasta. I have yet to observe N. cliftonii in flower myself, though it seems superficially similar to its East Coast counterpart.
Why should we grasp hold of a plant already in the natural process of fading from existence? Because relic species such as Neviusia are intrinsically valuable, affording us a keyhole through which to observe life as it may have existed millions of years ago.
TYPE OF PLANT: deciduous shrub
HEIGHT/SPREAD: 3-6 ft/3-6ft: can spread by stolons into thickets several yards wide
FORM: upright and somewhat open, with elegantly arching branches
LEAVES: alternate; oval or oblong; doubly serrate above middle
FLOWERS: appear in cymes; petals absent; the stamens, numerous and white to light green, are the showy part of the flower
BLOOM PERIOD: April-May
HARDINESS: USDA Zones 4-8: Sunset Zones 4-5, 7-9
EXPOSURE: sun or partial shade
SOIL: moist and well drained
WATER NEEDS: moderate
PROPAGATION: by seed or softwood cuttings