Three Lepidote Rhododendrons
S. D. Coleman, Fort Gaines, Georgia
In more recent years much has been said about three of our eastern rhododendrons, namely, Rhododendron minus, R. carolinianum, and R. chapmanii. All are of the lepidote division, "having scales on the underside of foliage," and all are classed as small leaf type rhododendrons.
R. minus "Michaux", type location: Bank of Savannah River. Possibly named after seeing R. catawbiense and R. maximum. R. carolinianum "Rehder", typical location: the Blue Ridge Mountains of North Carolina.
R. chapmanii "A. Gray", type location: two locations; Port Saint Joe, Florida, and a point southwest of Jacksonville, Florida.
Of the three species the R. minus has the larger flower truss, sometimes up to fifteen flowers to a truss. Individual flowers have longer tubes, and the flowers are evenly colored from a white blushed pink to a deep pink. R. minus has larger and more rounded leaves on lateral limbs. More will be said of this species. It was growing naturally on the Trail, and is therefore, a Southern plant.
R. carolinianum does not have as many flowers to the truss and individual flowers do not seem to be quite as large as those of R. minus. The corolla tube is shorter. Colors range from pure white to many shades of purplish pink. The foliage seems to be more acuminate than R. minus and slightly smaller. The two species grow pretty much alike and the average person cannot tell them apart, unless they are in flower. Many botanists call the R. carolinianum in the mountains R. minus. It is a mountain plant.
R. chapmanii flowers somewhat remind you of those of the azalea, R. canescens, having long tubes of a deeper color than the lobes. The blossom is a nice pink. It is a very pretty blooming plant. The plants I have grow bushier, and the foliage is more reticulate than that of the other two species. R. chapmanii blooms a little earlier.
From my findings I would say the larger groups of R. minus are found on the Chattahoochee River, including it's tributaries in both Georgia and Alabama. The name "minus" is misleading. If you find on the hillside a bed or one plant in bloom you will see a beautiful sight. R. carolinianum blooms over quite a season.
From plants collected from many stations I would think that in North Georgia, where the two species R. minus and R. carolinianum merge, you can select plants that have been mixing over the years. In these plants the corolla tube would be longer than the regular type a little further north.
Although I have some R. carolinianum from the higher mountains, also, from the valleys, I find that they all do well here, and it is strange that some of these plants did not come south on some of the streams. In my travels in search of material for the Trail, I have not seen the first R. carolinianum in this section of Georgia or Alabama. Where so many R. minus grow, I do not see any advantage in crossing the two.
I don't know just how far north R. minus will grow, but I have heard from Pennsylvania and it grows well in the more Eastern part. R. chapmanii, also, will grow in the same area. This plant from Florida is the earliest to bloom. It is a very pretty blooming plant, but does not grow quite so fast as R. minus and seems to grow bushier. The corolla tube seems to have a deeper color than the lobes. The plants have become so scarce in the wild, that I did not see a pure white.
The R. carolinianum has the advantage in pure white types. For hybridizing, R. minus has its advantage in having more flowers to the truss and in being a plant for lower elevations. It can be used for bringing various lepidote combinations to the southland and other milder climates. R. chapmanii has many good features. It will grow and bloom as far north as Massachusetts, as I have just heard from a friend.
These Species Breed True
My version of a species is a plant in nature that will reproduce a likeness of itself from seed. Now with seed from R. carolinianum you will get R. carolinianum; seed from R. minus produce R. minus; and from seed of R. chapmanii you get R. chapmanii.
I have only studied the living plants transplanted from many stations on the trail. All are growing beautifully. All of the plants from the mountains continue to be R. carolinianum. They were collected from several stations, most of them blooming at different times. All of R. minus were from this section on hillsides and on tributaries of the Chattahoochee River. Some were already growing on the Trail. Seeing both plants in bloom on the Trail, one can tell the difference. R. carolinianum has the widest variations in color. Even R. minus has a pretty near white and varies to deep pink.
All in this small leaf series make nice plants for the north side of the lower type buildings or other partially shaded locations. These plants can be cut to suit each individual, or can be cut for flower arrangements, being careful to cut here and there in order to give flowers each season, instead of shaping the plant all at one time. Plants in partial shade have prettier foliage, and the flowers hold up better and last longer. Fresh cut flowers last well in arrangements.
'Dora Amateis', a new hybrid of R. carolinianum crossed with R. ciliatum should be good in all sections, in the landscape as well as individual plants. All that these plants need is a well prepared bed with plenty of humus. Keep well mulched unless in a wooded area around branch heads or on hillsides of running streams as along the Trail. All we have to do is try to keep vines from taking over. We have beautiful flowers each year, unless one or two of our R. carolinianum bloom too late and catch the dry spell. When this happens, mulch well and it is taken care of. If in a park or around a home, these plants should be watered and mulched. Large or small oak leaves could be used and are not unsightly. If the R. minus blooms too heavily, it is best to take out most of the seed trusses, just as the flowers fade. This insures good blooms the next year. I believe this is true with most Rhododendrons. I have also had this happen in some species of azaleas. As I have observed all three species in nature, and about the same age plants on the Trail, in the same growing conditions, I would say R. minus was the larger growing plant.
We, Dan, Jr., my son-in-law Frank Gilreath, and myself, found R. chapmanii growing on sand dunes, containing lots of humus. Dan, Jr., made the lucky find. The plants were easily dug with the sand humus clinging to the root system, and were planted as they were on the Trail. All grow nicely in their new home.
The little plant I found in the high Smoky Mountains, possibly on the Tennessee side, and named "R. gilreathi" will have to be evaluated by Dr. Henry T. Skinner. I lost my plant and gave him the type location. It is the little rhododendron which has small, saucer-like flowers of a violet color, and in time will grow to three or four feet. The plants I saw were about two to two and one-half feet.
Some Cultural Hints
With too heavy blooms and too many seed pods, there are few flowers the next season. If the plants grow too spindly, take a sharp knife or razor blade and remove the center growth bud before the new growth begins. Too much low shade causes this. With a little sunlight the plants will nearly shape themselves and you get more blooms. Plant in a well drained, sandy, heavy humus soil, or top with a few inches of forest humus, a little peat moss, or "perlite." I have used both or all three for better results.
I am not a taxonomist, but have studied the living plants and have separated our native species of the eastern rhododendrons and azaleas. There is still much to be done, and there are yet some to be separated. Each species has many variations, and I think Linnaeus gave us the best system yet worked out, and a beautiful conversation subject. I still think Michaux, Gray, and Rehder were right in separating into three separate species, these three lepidote rhododendrons.