An odd variant of Coreopsis grandiflora proved to be a characteristic summer wildflower of all but the more geographically peripheral Ketona Glades. Aside from the comparatively late anthesis (typical C. grandiflora enters anthesis in late spring), their remarkable leaning habit was the first attribute that impressed us about these plants, which otherwise seemed clearly assignable to C. grandiflora. Given the severity of the habitat, one might attribute the peculiar habit to environmental factors. However, plants of C. grandiflora growing in the drought-prone, nutrient-poor soil of other outcrop-types grow stiffly erect. Like many plants of harsh habitats, it is only when the latter are brought into the more hospitable conditions of the garden that they become "leggy." Upon further study, another distinctive characteristic of the Ketona Glade Coreopsis became clear, a marked tendency for the leaves to have fewer divisions.
Coreopsis grandiflora Hogg ex Sweet var. inclinata J. Allison, var. nov. TYPE: Alabama: Bibb County, ca. 12.0 km. NNE of Centreville, ca. 1.0 km WSW of the mouth of Pratt Creek. "Pratt Glade West," Ketona Dolomite outcrop ca. 0.08 km N of Pratt Creek, 15 Jul 1999, James R. Allison 12086 (holotype, US; isotypes: AUA, BRIT, DUKE, FLAS, FSU, GA, GH, IBE, JSU, MICH, MO, NCU, NY, TAMU, TENN, UARK, UNA, USCH, VDB). Figure 4.
Inter varietates C. grandiflorae Hogg ex Sweet, foliis inferioribus caulis plerumque simplicibus aut tripartitis, segmentis eorum linearibus vel linearibus-oblongis, et sub anthesi caulibus procumbentibus vel leniter ascendentibus differt.
Perennial herb, from short rhizomes, glabrous except for marginal cilia. Stems usually several, (2.4) 3.3-5.7 (6.6) dm long, finely striate-sulcate, ascending to reclining at maturity, green or maroon, or brown with age, at anthesis usually with at least 6 nodes with persistent leaves. Leaves normally opposite, very gradually reduced above, mostly 4.2-15 cm long (including the proximally ciliate petiole), ciliate or eciliate, lowest leaves usually simple, mostly 4-11 mm wide, withered by anthesis; within a few nodes upward from the base leaves remaining simple or becoming 3-lobed, the lateral lobes narrower than and less than the length of the central lobe, mid and upper cauline leaves remaining simple or more often pinnately divided into mostly 3 or 5 linear to linear-lanceolate segments (0.7) 1.0-6.0 mm wide, some of these occasionally with one or more small additional lobes, margins otherwise entire. Inflorescence a solitary, terminal head or more often several (-9) heads in a terminal corymb, its branches with leaflike basal bracts, peduncles 11.5-17 (19) cm long, sometimes with 1 or a pair of variably positioned, linear bracteoles, often 1 or a few heads pedunculate from medial leaf axils. Heads mostly 2.2-5.8 cm wide; involucre campanulate, biseriate and dimorphic, phyllaries conspicuously pale-margined, the outer usually 8, green, linear-lanceolate, (5.5) 6.5-8.0 (9.5) mm long, 1.4-2 mm wide at the base, erect in early bud, ascending and often with recurved apices at anthesis, often reflexed in fruit, the inner phyllaries appressed, golden yellow, lance-ovate, acute, (7.1) 8.7-11 (12.1) mm long, 1.9-3.7 mm wide; rays neutral, 7 or 8, sunflower yellow, mostly 1.5-2.2 cm long, mostly 4-toothed, sometimes these with 1 or 2 smaller, secondary teeth; disk yellow, 0.9-1.4 cm across, the narrowly campanulate florets numerous, (4) 5-lobed, (2.8) 3.1-4.5 (5) mm long, lobes (0.5) 0.7-0.8 mm long; chaff linear-subulate, scarious-margined proximally, 6-7 mm long, 0.5 mm wide. Pappus a pair of deciduous, ovate, erose scales, 0.3-0.5 mm long, as wide as long or nearly so. Fruit an incurved, flattened achene, the larger, inner ones mostly broader than high (including a pair of well developed, lateral wings), body dark brown, papillose, 1.4-1.8 mm across, the inner face with a callus at base and apex, the wings tan to reddish brown, usually entire, each 0.6-0.9 mm wide. Chromosome number unknown.
Flowering late June and July, sporadically until frost, fruiting July-frost.
English Name: Ketona Tickseed.
Paratypes. Alabama: Bibb Co., 12.5 km NNE of Centreville, "Eastside Glade," 26 Sep 1992, A. and S. 7223 (UNA); 14.0 km NE of Centreville, "Starblaze Glade Southwest," 24 Jun 1998, J. Allison and T. McQuilkin 11013 (AUA, DUKE, JSU, UNA); 14.3 km NE of Centreville, "Starblaze Glade Northeast," 6 Sep 1992, A. and S. 7121 (JSU); 14.9 km NE of Centreville, "Brown's Dam North Glade West," 15 Aug 1998, A. 11331 (GA, MO, NY, UARK, UNA, US, VDB); 15.3 km NE of Centreville, "Desmond's Glade," 17 Jul 1999, A. 12092 (AUA, BRIT, DUKE, FLAS, FSU, GA, GH, JSU, MICH, MO, NY, UARK, UNA, USCH, VDB); 17.3 km NE of Centreville, "Enchanted Glade," 15 Aug 1998, J. Allison and M. Moffett 11320 (AUA, GA, UNA); 17.8 km NE of Centreville, "Alligator Glade," 19 Aug 2000, A. 12502 (AUA, GH, JSU, MO, NCU, NY, TAMU, UARK, UNA, US, VDB).
Coreopsis grandiflora var. inclinata is a plant of full sun. In view of this fact, and given its time of flowering and root system lacking any apparent specialization for water storage, it is an amazingly drought-resistant herb. Although all of central Alabama had suffered near record-breaking drought and heat for the preceding several weeks, the Coreopsis was still flowering in late July 2000, though the glades seemed more parched than at any other time during the study.
The low, sprawling habit of Coreopsis grandiflora var. inclinata, so unlike that of the other varieties, appears to be an adaptation both to recurrent low soil moisture levels and to a difference in population density and community structure. It is a plant of open, somewhat shallow-soiled areas on the Ketona Glades, where it is normally found as scattered, reclining individuals facing little competition, either from others of its kind or from taller vegetation. Other varieties, by contrast, whether on outcrops or on roadsides, often grow in dense, showy patches where they face greater competition, both intraspecific and from diverse, many potentially shading, species. There the erect form has adaptive value in competing for light, both for photosynthesis and for enhanced visibility of flowers to pollinators. Even though the heads of var. inclinata are usually borne within 2 dm of the substrate, the sparseness of taller vegetation leaves the flowers well exposed and easily perceived by the visitor, whether human or insect. Given the severely drought-prone habitat where it is found, the adaptive value of var. inclinata's peculiar habit, at least to an entomophilous species, is clear: a plant that is able to grow low to the ground and yet still attract pollinators can subsist with less moisture than an erect form more exposed to the drying effect of winds.
Examination of herbarium specimens was of limited value in understanding the patterns of variation of outcrop populations of Coreopsis grandiflora, particularly in evaluating the differing taxonomies espoused by Edwin Smith (1976) and Arthur Cronquist (1980). According to Smith, Alabama and other states east of the Mississippi have three varieties: var. grandiflora, var. saxicola (Alexander) E. B. Sm., and var. harveyana (Gray) Sherff. Variety saxicola is distinguished primarily by possessing fimbriate achene-wings, and var. harveyana by having median and upper leaves with very narrow segments. Cronquist recognized only vars. grandiflora and saxicola. The normally entire achene-wings of the Ketona Glade plants indicate no close affinity to var. saxicola, and the latter is excluded from the following discussion.To arrive at a better understanding of patterns of variation in Coreopsis grandiflora, we made repeated visits, at different times during the growing season, to several populations each of vars. grandiflora, inclinata, and harveyana, including several Arkansas populations of the latter on Ozarkian glades, where var. harveyana is one of the dominant herbaceous plants. Had our studies been limited to the herbarium, we probably would have agreed with Cronquist's taxonomy, and might have remained uncertain about the distinctiveness of the Ketona Glade populations. Herbarium specimens of herbaceous plants like Coreopsis grandiflora are virtually always of flowering or fruiting material. This is entirely understandable, but in rare instances serves to obscure the differences among taxa, such as those in which the leaf morphology is most distinctive prior to anthesis. Such is the case with the plants under discussion. Varieties grandiflora, harveyana, and inclinata are strikingly different in leaf morphology a few weeks prior to flowering (see Figure 4), but the lower leaves are usually withered by the time of anthesis, and so the differences become less apparent. In variety harveyana there is an abrupt narrowing of leaf segments above the lower nodes, while vars. grandiflora and inclinata have the segments very gradually narrowed upward; leaves of var. inclinata differ from other varieties by having fewer divisions. The tendency for the lower leaves to be withered by anthesis is especially pronounced in var. inclinata, because it also differs from varieties grandiflora and harveyana by entering population-wide anthesis more than a month later than they do. This phenological difference, combined with the reduced degree of leaf dissection, reclining habit, and restricted distribution, is sufficient to justify recognition of the Ketona Glade populations at the infraspecific level, at the very least. The senior author is not convinced of the utility of distinguishing more than one infraspecific level, and is predisposed to use the subspecies to represent that rank. However, the varietal rank is employed here, and later in Erigeron strigosus, to conform best with the currently prevailing infraspecific taxonomy of these groups (e.g., Smith 1976, Cronquist 1980, USDA 2000).
A further difficulty in interpreting variation in Coreopsis, both in the herbarium and in the
field, is frequent hybridization. The crossing experiments of Smith (1976) have shown that varying,
often high degrees of interfertility exist among the various taxa, and it would seem that in many cases
the chief isolating mechanisms are either spatial (allopatry or differences in habitat preference) or
phenological (e.g., in the Piedmont of Alabama and Georgia we have observed C. auriculata L., C.
lanceolata L., and C. grandiflora to be sympatric but with staggered peak anthesis, in the sequence
given). The disruption of natural community boundaries by logging and other land-disturbing
activities has apparently brought into close contact many species of Coreopsis (as well as Helianthus
L., Silphium, etc.) that were formerly effectively isolated by differing ecological preferences, and
apparent hybrids and hybrid swarms are the result. In Coreopsis, many of the species seem pre-adapted to conditions now found along highway and other rights-of-way. Such places often support
populations of plants that seem to combine characters of different taxa.
In the case of Coreopsis grandiflora var. inclinata, we found putative hybrids with
C. pubescens Ell. at two sites (A. and S. 7633, AUA, UNA, VDB; A. 11933, JSU, UARK, UNA),
one where a road was built across a glade, the other a glade disturbed in the past by logging. The
narrow, pubescent, little-divided leaves caused Allison to key the earlier collection originally to
C. pubescens Ell. var. debilis (Sherff) E. B. Sm., and to report, in error, that taxon to the Alabama
Natural Heritage Program as present in Bibb County.