Tuesday, September 8, 2009

Notes from the Field: Part 1

Native Stewartia
by Frederick R. Spicer, Jr.
Executive Director

Flowers of Stewartia malacodendron (silky stewartia). Both species can have purple stamens, but the united style, clearly seen at the center of the flower, is diagnostic for S. malacodendron. The style of S. ovata is divided into five distinct parts. Image taken on 5/16/2008 at Oak Mountain State Park, Shelby County, AL.
In May of 2003, in a densely wooded buffer area off a cul-de-sac in a small residential neighborhood of Vestavia Hills, AL, I saw Stewartia malacodendron (silky stewartia) in the wild for the first time. Despite the inherent thrill (a minor Holy Grail for me, anyway) of seeing an uncommon plant in its native habitat for the first time, it was an otherwise inauspicious beginning for what has become somewhat of a seasonal rite for several botanical institutions now cooperating to study this handsome native plant and Stewartia ovata
(mountain stewartia), its close relative (see the maps at the end of this post for more information on native habitats in the U.S. and in Alabama).

These institutions (in alphabetical order) are Atlanta Botanic Garden (Atlanta, GA, represented by Storza Woods curator Jamie Blackburn), Birmingham Botanical Gardens (represented by me and Patrick Daniel, curator of the Kaul Wildflower Garden), Mt. Cuba Center (Greenville, DE, represented by director Rick Lewandowski), and Polly Hill Arboretum (West Tisbury, MA, represented by director Tim Boland). It would be a huge mistake to say this kind of work happens in an institutional vacuum, and only among those listed. A number of individuals, businesses and other institutions have played, and perhaps will play, a role in stimulating and augmenting our efforts.

However, one person, a nursing professional with an unassuming demeanor, an unabated love of nature and an uncanny knack for plant-sleuthing, deserves special mention for his important place as the team’s keystone. After all, he’s the one who knows where many of the Stewartia are. Jack Johnston has been hunting, and more importantly finding, native stewartias in the woodlands of the southeastern US for over two decades. Interested in plants and gardening since his youth, Johnston had seen pictures of stewartias in books, but it took a first-hand experience with a flowering Stewartia malacodendron in an Alabama forest to seal his interest. Remembering that introduction, Johnston says, “I was amazed by the beauty of those flowers.”

Jack Johnston harvesting seed of Stewartia malacodendron. He employs a six-foot long, specially-hooked stick carved by him for this purpose (seen at right-center of image). With it, he can easily extend his reach and grasp, and gently bend higher seed-bearing branches to hand. Image taken 9/14/2007 along the Locust Fork of the Black Warrior River, Blount County, AL
From his home near Lake Rabun, in northeastern GA, Johnston has scoured numerous coves, hollows and riverine hillsides in AL, FL, GA, NC, SC, and TN for his horticultural Brigadoon. He quickly determined that special conditions were needed for either species to prosper in the wild. Young, crowded forests simply created too much shade. On the other hand, older, “stable forest conditions, with sufficient canopy gaps, were the most likely places to locate the plants. So I confined my searching to old forests, in specific locations with the right amount of moisture.” Johnston not only finds stewartias, he has also been collecting seeds, taking cuttings, propagating them (no easy task), growing them, and giving them away; he’s been a virtual one-person Stewartia promotion society, and he’s quite good at it.

My own experience with Stewartia was, until I moved south, confined to the deciduous Asian species, and it is with these species that most gardeners are familiar. In my former, more northern plant pursuits in New Jersey, I grew Stewartia koreana (Korean stewartia), S. monadelpha (tall stewartia), S. pseudocamellia (Japanese stewartia), S. rostrata (beaked stewartia), and S. sinensis (Chinese stewartia). With their gorgeous white summer flowers, outstanding fall color, pest-free nature, exquisite bark, and clean winter habit, they are among the most highly-prized four-season small trees; reams have been written about their enduring and endearing beauty. Yet these are truly plants of colder climes and they all have trouble growing in the unrelenting high heat and humidity, often coupled with droughts, found in most low-elevation southern locations.

We have several plants of Stewartia here at The Gardens, probably S. koreana, but they flower weakly and lack general vigor. I’m being kind; a more accurate description would be that they are generally in decline (bless their hearts). Similar stories can no doubt be found throughout the south, especially, I imagine, among northerners who moved south to satisfy their “zone envy”. A balmier clime gave them the ability to grow previously not-quite-hardy plants (and they could toss their snow shovels, too), but they lost the ability to grow some of their former favorites in the process, Asian Stewartia among them. Gardening, like life, is about choices.

However, the genus Stewartia (or Stuartia, in deference to our British friends, or other admirers of John Stuart, 3rd Earl of Bute, after whom the genus was named but whose surname was misspelled by Linnaeus, the bestower of the generic plant name) is represented by two species in eastern North America and both have southern affinities: the aforementioned Stewartia malacodendron (silky stewartia) and S. ovata (mountain stewartia). From a strictly ornamental perspective, these are inferior to the Asian species, smaller, too, and in any event are not well-adapted to bitterly cold winters. The Rutgers Gardens, my collegiate plant-hunting haunt in New Brunswick, NJ, had a specimen of S. ovata. It looked like so much horticultural detritus next to its handsome Asian brethren, so I didn’t give it much thought at that time.

Subsequently, I saw both native species in several southern arboreta (North Carolina Arboretum and Biltmore Estate in Asheville) before moving here, and despite not having exfoliating bark and brilliantly multi-hued fall colors like their Asian cousins, their conspicuous flowers (and dapper dispositions in a favorable climate) were enough to make me covetous. Soon after arriving in Birmingham, local plant savant Michael Steiner (now a practicing architect in New York City) directed me to a small population of S. malacodendron in Vestavia Hills, not four miles from The Gardens. I crawled through the underbrush, and pulling the smilax thorns out of my arm, tripped into a small stream. After clearing some spider webs from my face, I looked up, saw the unmistakable flowers, and was instantly smitten.  I could have my southern home and stewartias, too. So I quickly obtained several small specimens and had them planted here at The Gardens; they promptly died. I planted one in my home garden; it died within days. Clearly I was doing something very wrong, but what? Tales of local gardeners were filled with experiences similar to my own. These plants were apparently very difficult to cultivate. But why?

Sometime plants are uncommon, as my friend the eminent Rutgers University plant-breeder Dr. Elwin Orton would say, for a reason. He was referring to plants with very limited ornamental appeal. To him, such plants were simply not worth having, as there were many better (read: prettier) plants that should occupy valuable real estate in finite garden spaces. But these were not some obscure Amelanchier or Crataegus lacking in horticultural distinction and without friends in botanically high places. These were stewartias, certainly with enough ornamental (if not nomenclatural) clout to hold their own. I was very curious about their apparent lack of natural abundance and garden popularity

I knew peripherally that our native stewartias had very limited native distribution, and this was confirmed with some research. I assumed (correctly, as it turned out) that their habitat preferences were pretty specific, a common trait with uncommon plants. I knew they were scarce in commerce, too, assuming (correctly again) that they were relatively difficult to propagate. Perhaps viable seed was difficult to come by, or cuttings were reluctant to root. Now I was learning that even very good gardeners had more than a little trouble getting either species to thrive in a garden setting. With so many easier things to grow, why would anyone waste time, money and (yes, Dr. Orton), space with recalcitrants? Oh, but this is precisely what some gardeners do (or wish they could do).

A short digression: the appellation “camellia” often replaces “stewartia” in the common names I hear locally, and in fact, those names are somewhat widely-accepted for our native species (but, interestingly, not for the Asians). This makes some sense: true camellias and stewartias are both members of the Theaceae, the tea family (Camellia sinensis, the tea of commerce, being the family’s standard-bearer), and the flowers of both are superficially similar in appearance and structure. Nevertheless, I sometimes feel that referring to one plant by using the name of another diminishes one, or both, of the plants in question. Camellia japonica, despite its heat-loving tenacity and the buckets of giant flowers it unleashes in the dead of winter, is a bit on the stodgy side, if you ask me; “graceful” is just not a word that comes to mind. So I’ll stick to stewartia; on its own it’s enough of a compliment.

Distribution map of Stewartia malacodendron 
(silky stewartia) by state

Populations within this overall area are widely and irregularly distributed due to specific habitat preferences. Populations typically consist of low numbers of individuals. They are generally found on sloping, well-drained soils in the Piedmont and Coastal Plain, in gaps in mature forests, and often near streams and rivers, but above seasonal flood levels.
Distribution map of Stewartia malacodendron 
(silky stewartia) by Alabama county
Spotty distribution is typical for the species and S. ovata (mountain stewartia) throughout their respective ranges. The latter is generally found in higher elevations such as in the Ridge and Valley and Southeastern Appalachian provinces, but has the same habitat preferences as the former.
PLANTS profile for Stewartia (stewartia). Retrieved August 24, 2009 from the USDA website: http://plants.usda.gov.

Look for Part2...coming soon!