By Robert Dunlap
In March 2022, I was lucky enough to find a new population of Turk’s cap lilies (Lilium superbum) containing about 500 stems in two colonies in McCracken County while searching for spring ephemerals. Additional searches yielded five more colonies containing another 1,700 individuals, all within about 75 yards of each other.
Due to my unfamiliarity with this plant and the lack of blooms, it took a little research to verify they were Turk’s cap lilies and not their close relative, Michigan lily (L. michiganense). Dichotomous keys usually differentiate between these plants using flower characteristics i.e., tepal curvature and anther length, which is not very helpful if you don’t have a flower to examine. Several online sources mentioned two vegetative characteristics to check: L. superbum has smooth leaf margins (not finely serrate), and the bulbs are white (not yellow). The plants I found exhibited both of these features so I’m going with the Turks cap lily. This plant was found by Mr. Raymond Athey less than 10 miles from this site in 1978, so there is historical evidence supporting the L. superbum identification, as well.
That being said, some botanists are reluctant to rely on the vegetative characteristics described above and feel that positive identification requires examination of flower structures. After being moved to more suitable sites in the future, my hope is that some of these bulbs will produce flowers allowing their identity to be determined beyond any doubt.
The species name is pronounced “superb – um” as opposed to “super – bum” and refers to the flowers, which can be translated from Latin as proud, superb, excellent, splendid, or magnificent. Mr. Linnaeus did a good job naming this plant back in 1762!
Ecology
Turk’s cap lilies are classified as threatened in Kentucky by the Office of Kentucky Nature Preserves and probably occur in less than a dozen counties. They are scattered across the state from Black Mountain in Harlan County in the east to Carlisle County in the west. Threatened plants are defined by the OKNP as “… likely to become endangered within the foreseeable future throughout all or a significant part of its range in Kentucky.” So, the assumption is that their numbers are declining and will continue to do so in the future.
The BONAP map (Biota of North America Project) to the right displays the counties where Lilium superbum occurs in the U.S. Light green counties have stable populations while those highlighted in yellow have populations that are small and possibly declining.
It is generally more common in upland areas along the Appalachian Mountain chain, which includes Black Mountain. So how did they end up in McCracken County and across the Ohio River in southern Illinois? Some botanists have theorized that many southern plant species migrated north and west following the Cumberland River and the Tennessee River, which join up with the Ohio River near Paducah. Perhaps the lilies travelled from the mountains of North Carolina and Tennessee along these waterways over the last several thousand years or so.
Culture
Lilium superbum prefers to have its head in the sun and feet in rich, moist, well-drained soil. They are often found growing along creeks and small streams where sand and gravel were deposited in the past.
Unfortunately, the 2,200 bulbs at this site are growing in moderate to complete shade. In low light conditions, Turk’s cap lilies will often go into survival mode and mimic the life cycle of our spring ephemerals by producing stems and leaves that survive 2-3 months before dying back (senescing). This behavior is exhibited by several of our other native lilies. Despite this short growing season, many bulbs manage to reproduce vegetatively by means of rhizomes. A bulb will produce one or two underground stems and a new “daughter” bulb will appear 2-3 inches from the “mother” resulting in dense colonies. The small colony shown (5 sq ft) contains stems and leaves from about 200 underground bulbs. I don’t know if all these plants descended from a single parent that got shaded out many years ago, but I suppose it is possible.
Shown above is left) a mother bulb with two daughters growing at the tips of two rhizomes and right) stems and leaves in late May 2022 in the process of senescence. The above ground plant parts die back but the underground bulbs are able to survive for many years, perhaps decades.
Management plan
By mid-summer 2022 I knew where 2,000+ bulbs of one of Kentucky’s most spectacular native plants were growing and that none of them would likely never produce a flower. To rectify this situation, I consulted with the property owner who agreed with a plan to relocate bulbs to sunnier locations. Reducing shade by removing trees or trimming branches is not practical at the site. Bulbs were excavated in the fall and planted at two sunny locations nearby. These plants are currently doing well (mid-July), which supports the theory that relocating bulbs to favorable sites should allow them to achieve maturity. They will probably require several more growing seasons before producing flowers.
About 50 daughter bulbs were removed from mother bulbs and planted separately with mixed results, probably due to the various levels of maturity involved. I intend to leave the daughters connected to the mothers in future transplants.
It would seem that the prospect of getting plants from these bulbs to produce flowers is quite good. Coaxing those flowers to produce viable seeds is another matter. L. superbum is self-incompatible and cross-pollination with the help of butterflies, bees and hummingbirds is required for seed set. It is not known whether the bulbs from the different colonies are sufficiently diverse from a genetic standpoint to allow sexual reproduction to occur. Bulbs from multiple colonies will be combined at future planting sites and any seed pods that are produced will be examined. Cross your fingers!
In the wild, Turk’s cap lily bulbs are eaten by rodents and the leaves and flowers are consumed by rabbits and deer. OKNP has been involved for many years in a project to restore populations of wood lilies (Lilium philadelphicum) in the Cumberland Plateau. To provide seed for propagating new plants, specimens had to have cages built around them to prevent losing flowers and seed due to deer herbivory. I expect similar precautions will need to be taken to protect transplanted Turk’s Cap Lilies. No signs of herbivory have been noticed at the McCracken County site, but the plants are only present for 8–10 weeks in the spring when other, more desirable food sources may be available. I suspect our deer have found that the flowers taste much better than the leaves!
Moving forward
With so many bulbs to work with, I feel confident that transplanting them to sunnier sites on the same property will result in mature plants that will produce the “proud, superb, excellent, splendid, and magnificent” flowers that Turks cap lilies are named for. The only limiting factor to this rosy outlook is the number of bulbs I’m able to transplant in the fall!
As a final note, remember that our rare plants are still out there ready and waiting to be found –- you just have to get out there and look!
Robert Dunlap is an amateur naturalist living near Paducah who owns every Peterson Field Guide that has ever published.