Stems

S. kentuckiense has from one to three or more glabrous (hairless) stems extending from the root base. These stems can be decumbent, growing horizontally along the ground and turned up at the ends,^{[lower-alpha 2]} to ascending. They are green to reddish-brown.^[5]

Leaves

The species has thin alternate^[7] leaves that are dark green to bluish-green^[5] with glabrous faces.^[8] Leaves occur at the base, on stems, and on inflorescence branches. Depending upon the locations of the leaves on the plant, the apices, or tips, can be noticeably pointed (acute^{[lower-alpha 3]} to acuminate^{[lower-alpha 4]}), obtuse,^{[lower-alpha 5]} mucronate,^{[lower-alpha 6]} or cuspidate.^{[lower-alpha 7][5]}

Basal leaves are either without leafstalks (called petioles), making them sessile, or they have very short petioles with sheathing wings that are fringed with hairs on their edges, making them ciliate. The basal leaves are oblanceolate^{[lower-alpha 8]} to obovate^{[lower-alpha 9]} with obtuse^{[lower-alpha 5]} apices, and their bases are cuneate^{[lower-alpha 10]} (wedge-shaped) to attenuate.^{[lower-alpha 11]} Their margins (edges) are entire, meaning they are smooth with no teeth or lobes. Rarely, they can be sparsely saw-toothed, also called serrate. Basal leaves range in lengths from 10 to 70 millimeters (0.4 to 2.8 inches) and widths from 3 to 5 mm (0.12 to 0.20 in). The basal leaves grow in a rosette that develops prior to flowering. These leaves wither or die during plant growth, and at the time of flowering, another rosette of basal leaves forms.^[5]

Lower and middle stem leaves are sessile or may have petioles with narrow wings. They usually wither by the time the plant flowers. The leaves are oblanceolate^{[lower-alpha 8]} to linear-oblanceolate and range in lengths of 70 to 105 mm (2.8 to 4.1 in) and widths of 2 to 4 mm (0.08 to 0.16 in). They have attenuate^{[lower-alpha 11]} to cuneate^{[lower-alpha 10]} bases that can be auriculate^{[lower-alpha 12]} (shaped like earlobes) or clasp the stem.^[5]

The linear-lanceolate^{[lower-alpha 13][lower-alpha 14]} to narrowly subulate^{[lower-alpha 15]} distal^{[lower-alpha 16]} leaves are sessile and get progressively smaller as they approach the flower heads. Distal leaf bases are subauriculate^{[lower-alpha 12]} (somewhat earlobe-shaped) and can clasp the stem. Their margins are entire but have cilia closer to the branches. These leaves are glabrous on both sides and range in lengths of 5 to 65 mm (0.2 to 2.6 in) and widths of 1 to 4 mm (0.04 to 0.16 in). The small, 3-nerved inflorescence leaves are often formed in clusters called fascicles.^[5]

Flowers

Symphyotrichum kentuckiense is a late-summer and fall blooming perennial,^[5] with flower heads that are about 25 mm (1 in) wide^[8] and have blue,^[9] blue-violet,^[5] pink, or purple ray florets^[8] opening August through October. The flower heads grow in leafy paniculiform to racemiform arrays on inflorescences that are straight and ascending or can have wide angles between the branches. Divaricate branching^[5] can cause the plant to appear as a small shrub.^[10] At times, the flower heads can be secund, appearing on one side of the branch.^[5]

Each flower head is on a glabrous peduncle that ranges from 4 to 20 mm (0.16 to 0.79 in) in length. There are 3 to 6 linear to subulate^{[lower-alpha 15]} and stiff, glabrous bracts on each peduncle. Bracts closest to the heads can be so long that their lengths exceed the heights of the involucres.^[5]

Fruit

The fruits (seeds) of Symphyotrichum kentuckiense are not true achenes but are cypselae, resembling an achene but surrounded by a calyx sheath. This is true for all members of the Asteraceae family.^[12] After pollination, they become tan to brown with an obovoid^{[lower-alpha 9]} shape, 1.5 to 2.1 mm (0.06 to 0.08 in) in length with 4 to 5 thin nerves, and with a few stiff, slender bristles on their surfaces (strigillose). They also have tufts of hairs (pappi) which are white and 3 to 5 mm (0.12 to 0.20 in) in length.^[5]

Chromosomes

The species has a monoploid number (also called base number) of eight chromosomes (x = 8). It has eight sets of its chromosomes, meaning it is octaploid, giving it a total chromosome count of 64.^[6]

Classification

Symphyotrichum kentuckiense is classified in subgenus Symphyotrichum section Symphyotrichum subsection Porteriani. This subsection contains four species in addition to S. kentuckiense: S. depauperatum, S. parviceps, S. pilosum, and S. porteri.^[13] It is the only octaploid within the subsection.^[6]

History

The basionym of Symphyotrichum kentuckiense is Aster kentuckiensis. Its name with author citations is Symphyotrichum kentuckiense (Britton) Medley. The plant was formally described as a unique species and named Aster kentuckiensis Britton by botanist Nathaniel Lord Britton in 1901 in his publication Manual of the Flora of the Northern States and Canada.^[14] The sample that was used by Britton as the holotype for A. kentuckiensis was collected in October 1898 by Sadie F. Price near Bowling Green, Kentucky.^[8]

Hybrid Symphyotrichum × priceae

At the same time that she collected what became the holotype for Aster kentuckiensis, Sadie F. Price collected a similar plant that Britton named Aster priceae Britton and included in its description that it is pubescent, or with soft hairs.^[8] In later floras by other authors, A. kentuckiensis was synonymized to A. priceae. In a 2021 journal article by botanist Max E. Medley, elements of the morphologies of A. kentuckiensis and A. priceae were confirmed to have been erroneously combined, and sometimes the former was ignored. Notably, this treatment resulted in floras written prior to Medley's paper applying the glabrous trait to A. priceae and S. priceae, which is incorrect, as this plant is puberulent.^[15]

In 1948, botanist Arthur Cronquist reduced Aster priceae to a variety of A. pilosus named A. pilosus var. priceae (Britton) Cronquist^[16] which Medley posited was a conclusion "based on misidentified specimens and [was] not appropriate."^[17] Subsequently, it was considered the non-hybrid species Symphyotrichum priceae (Britton) G.L.Nesom with S. kentuckiense and A. kentuckiensis as its taxonomic synonyms.^[5][9]

Medley suggested that the Aster priceae holotype and Britton's protologue were of the hybrid A. kentuckiensis × A. pilosus var. pilosus.^[15] He gave it the hybrid designation and acknowledged the name as Symphyotrichum × priceae (Britton) G.L.Nesom,^[3] with Aster priceae Britton as its basionym.^[18] Corrected synonyms of S. × priceae are A. priceae and A. pilosus var. priceae (Britton) Cronquist. As of October 2022^[update], this hybrid name was accepted by Plants of the World Online (POWO).^[3] The hybrid is a puberulent plant rather than a glabrous one, and its characteristics are intermediate between its parents.^[9]

Etymology

The specific epithet (second part of the scientific name) kentuckiense is a Latinization of the name of the state of Kentucky where the holotype was found. The hybrid's specific epithet priceae is a Latinization of the surname of the collector, Sadie F. Price.^[8] The species has the common names of Kentucky aster,^[6] Price's aster,^[9] Miss Price's aster, Sadie's aster,^[4] and lavender oldfield aster.^[5] "Old field asters" is a common name for subsect. Porteriani.^[13]