Spigelia gentianoides Chapman in A. DC. var. alabamensis K. Gould

During our initial exploration of the Ketona Glades, on May 30, 1992, Jim Rogers noticed a rather peculiar "gentian," with pink rather than the usual blue flowers. Upon returning home, Allison determined his collection, A. et al. 6670 (UNA), to be not a species of Gentiana L. at all, but a plant named for its striking resemblance to one, Spigelia gentianoides.

Prior to 1992, Spigelia gentianoides had been collected from three counties in Florida (Calhoun, Jackson, Washington), all in the Panhandle (USFWS 1990). However, the majority of collections of this species date from the 19th century, mostly Chapman's own specimens. Only two, possibly three, Florida localities are known today to support it, and it was designated a federal Endangered species in 1990 (USFWS 1990).

 During surveys in 1992 and 1993 we found Spigelia gentianoides at about 17 Ketona Glades, all close to the Little Cahaba River, populations totaling in aggregate several thousand individuals. After observations of populations in Calhoun and Jackson Counties, Florida, Allison recognized that the Florida plants (Figure 13) looked "different" in several respects, but reached no conclusion as to how many of the phenotypic differences seen would likely have a genetic basis (arguing in favor of taxonomic recognition) and how many might be attributed to the very considerable differences in habitat (arguing against separate taxonomic status).

The habitat of Spigelia gentianoides in the Florida Panhandle and where recently found in adjacent Alabama (by John MacDonald, Mississippi State Univ., pers. comm. 1999) is quite different, none of the sites there being at all rocky. Based on 1992 observations at extant sites in Calhoun and Jackson Counties, Florida, the original habitat of this species in Florida appeared to have been dominated by Pinus palustris and Aristida stricta Michx. A number of characteristic species of the longleaf pine-wiregrass community were persisting at the (Calhoun County) pine plantation site, due to periodic removal of the canopy and/or past episodes of fire. The visit to a Jackson County, Florida site, within Three Rivers State Park, revealed that many of these species appeared to have been lost there due to fire suppression, as a considerable hardwood component had developed.

A 1994 return visit by Allison to Three Rivers State Park resulted in the discovery of at least 100 flowering individuals in a portion of the park where the plant had not previously been known (Angus Gholson, pers. comm. 1994). The vigorous response to a preceding controlled burn by these plants, which probably had been languishing in a vegetative state, suggests that many, if not most, Florida populations of Spigelia gentianoides have been lost or are in the  process of disappearing as a result of fire suppression. By contrast, the Ketona Glade habitat is probably maintained more by rockiness and edaphic conditions. However, occasional wildfire in the ecotones would have served to limit encroachment from the glade margins. Such a role in the past for wildfire in maintaining the Ketona Glade ecosystem is indicated by the persistence, in the forest matrix surrounding some of the glades, of longleaf pine and such wiregrass-country associates as Sericocarpus tortifolius (Michx.) Nees and, less commonly, Carphephorus odoratissimus (J. F. Gmel.) Herbert.

In 1995, Katherine Gould, then at the University of Texas and engaged in systematic studies of Spigelia, contacted Allison, who provided her with directions to some of the Ketona Glade populations of S. gentianoides. After study of these populations, she concluded that they were sufficiently distinct to merit taxonomic distinction and described them (Gould 1996) as S. gentianoides Chapman in A. DC. var. alabamensis K. Gould.

The primary morphological differences noted by Gould between vars. alabamensis and gentianoides can be summarized as follows (var. alabamensis character states given first): leaves with upwardly curved margins and a narrower shape, lanceolate to elliptic, ovate, or obovate, with cuneate or rounded bases, vs. leaves plane and with a broader shape, broadly ovate with rounded bases; cymes with mostly 2-4 flowers, vs. 3-8; larger flowers (sepals 8-11 mm long, vs. 4-6 mm; corollas 36-50 mm long vs. 25-30 mm; pistils 24-27 mm long, vs. 17-19 mm); and corollas that open fully at maturity, the lobes often becoming fully perpendicular to the tube, vs. corollas with lobes that barely separate at all in anthesis. According to James Affolter (State Botanical Garden of Georgia, pers. comm. 2000), all of these differences are maintained when both varieties are raised from seed to maturity in a common greenhouse. This demonstrates that these characters have a genetic basis, supporting recognition of the Ketona Glade populations as a distinct taxon.

Spigelia gentianoides var. alabamensis appears well adapted to areas of the Ketona Glades where exposed to full sun, with attendant extreme heat and drought, as well as to the partial shade of glade-forest ecotones. Although the plants may form extensive patches in deeper shade, S. gentianoides var. alabamensis flowers more prolifically at glade and forest-island margins where it is shaded for only part of the day. Its overall distribution over the glades is similar to that of Castilleja kraliana except that it does not reach the westernmost glade within the range of the latter.