Trees, Shrubs and Conifers: It's about time...Yellowwood, 1 by ViburnumValley

ViburnumValley wrote:
OK, time to head off to another meeting, but before I go......a treatise!

I wrote this for publication eight years ago. I don't think I'd change a word.

Yellowwood (Cladrastis kentukea)

One of the challenges of the design profession is finding solutions to problems, and using these solutions to improve the everyday living conditions we all experience. Selecting trees to serve functionally is one method of solving issues of shading, massing, scale, screening, or strict ordinance standards. Creating a beautiful experience while meeting these more mundane criteria separates the top designers from the crowd. The class of species a designer specifies will highlight his/her effort to overcome the simple and the monotonous. Which leads to the yellowwood, a plant that is not used often, accidentally, or carelessly.

Yellowwood is a midwestern native (ranging from Indiana to northern Alabama and Georgia, to the Ozarks in Arkansas and Missouri, but nowhere very populous) occurring on moist limestone soils, though I’d venture to say most reading this article have never observed one in the wild. This is probably why it is so seldom known and grown. It is hardy to zone 4, performing admirably as far north as Minneapolis and Orono, ME. Yellowwood is an in-between size tree (up to 50-75’ tall and 40-60’ wide), and not a rapid grower either, maybe putting on a foot a year. While it occurs naturally in mesic coves and ravines in forests and along slopes near streams, most opportunities for use in today’s planted landscapes are much drier and in more disturbed soils. Yellowwood will fool you with its toughness, tolerating all these conditions, and providing multi-season interest as well. The smooth cool gray bark invites a rub of the hand; the gently arching vase-shaped branching habit calls for planting along walks, parking areas, and streets; the bright green of the summer foliage stays clean and contrasts well with darker-foliaged plants; and the warm orange-yellow fall color glows in early autumn.

Along Lexington’s New Circle Road and its cloverleafs stand some rugged individuals of yellowwood, most planted 25+ years ago in some really lousy soil/moisture/pollution conditions. Yet they flowered prolifically this year (along with most other yellowwoods around here) and showed why they are a gem among trees. I like to think that I have been a keen observer of the horticultural world, but there were yellowwoods popping up in bloom this spring (big ones, in prominent places) that I had never noticed before; I wonder if others noticed that as well. Cave Hill Cemetery in Louisville has the most extensive plantings of yellowwoods that I know of in Kentucky; it was truly an otherwordly feeling to walk under the cascading tresses of fragrant white blooms (hardly a twig was without a full 12-15” pendulous panicle).

The yellowwood suffers from a reputation of poor branching angles which can split, and thus the perception that it is weakwooded. Again, if the tree’s natural habit were observed, this notion would seem preposterous. It is single-trunked and widely branched. Most of its problems in cultivation are derived from the nursery production phase (creating a dense head on a small plant), and a natural unwillingness to prune a handsome plant once it is in the landscape a few years. Very few pests or diseases afflict yellowwoods; verticillium wilt has been listed, and I have noticed some magnolia scale this year as I have been collecting from the bumper crop of seed.

When I think about the placement of trees in landscape design, whether it be for a park, a horse farm, or my own yard, I look to provide a solid successful solution first. Functions like shade for a southwest exposure, screening a neighboring billboard, or providing a transition to the land from a tall building are all weighed first, and then imagination takes over. What species are not represented here, or nearby? Is there a season of color missing, or lack of fragrance? Finally, what character can be added as a nuance, for those perceptive enough to notice? If a plant selection can answer more than a couple of these questions (and yellowwood suffices this time), then the human environment becomes just a little bit more special.