Chelone obliqua

Stems 25–180 cm. Leaves: petiole 3–20 mm; blade broadly elliptic to narrowly elliptic, 45–197 × 8–35(–50) mm, base cuneate, margins once- or twice-serrate, teeth 1–7 per cm, abaxial surface glabrous or pilose, rarely villous, adaxial usually glabrous. Cymes 38–86 mm; bracts 4–10(–17) × 3–8 mm, ape× obtuse to acute or acuminate. Flowers: caly× lobes 7–10 × 3–7 mm, margins not or sparsely to densely ciliate; corolla dark pink to red to purple, sometimes paler to white abaxially, tube 14–22 mm, abaxial lobes (10–)12–19 × 5–15 mm, adaxial slightly keeled; palate yellow-bearded, rarely white-bearded; adaxial filaments (13–)16–27 mm; staminode 4–12(–14) mm, ape× white, rarely green or purple; style 16–34 mm.

Distribution

c, e United States.

Discussion

Varieties 3 (3 in the flora).

Chelone obliqua can be identified by its completely dark pink, red, or purple corollas with abaxial surfaces sometimes paler to white, yellow beards, and white staminodes. The species may be difficult to distinguish from other species of Chelone when rarely its beards are white or staminodes green- or purple-tipped. This may be due to rare intra- and interspecific hybridization (A. D. Nelson and W. J. Elisens 1999).

Chelone obliqua is allopolyploid (A. D. Nelson 1995; Nelson and W. J. Elisens 1999) and has a recombinant phenotype representing all three extant diploid species. Variation within C. obliqua reflects multiple independent origins (Nelson; Nelson and Elisens); some of the rare color variants could be due to this rather than hybridization (Nelson).

Chelone obliqua comprises two known chromosome races, 2n = 4x = 56 and 2n = 6x = 84. Tetraploids are found in the Blue Ridge Province; hexaploids are found in the Interior Low and Ozark plateaus as well as Central Lowland provinces and the Coastal Plain Province. Within each of these three physiographic provinces, distinct genotypes occur (A. D. Nelson 1995; Nelson and W. J. Elisens 1999; NatureServe, www.natureserve.org/explorer). Seven populations of C. obliqua were examined for this treatment, and it appears from this limited sample that the cytotypes might have regional ranges and minor morphological variation that support the varieties of C. obliqua as proposed initially by Pennell and Wherry and later treated as subspecies by Pennell. With the exception of caly× lobe margin indument, new characters are used to distinguish varieties because those used by Pennell had wide quantitative ranges or were highly variable qualitative characters.

Selected References

None.

Lower Taxa

Chelone obliqua var. erwiniae, Chelone obliqua var. obliqua, Chelone obliqua var. speciosa

Key

1	Staminodes 4–8(–12) mm; caly× lobe margins densely ciliate; Interior Low and Ozark plateaus, Central Lowland provinces.	Chelone obliqua var. speciosa
1	Staminodes (6–)8–12(–14) mm; caly× lobe margins not or sparsely ciliate; Coastal Plain and Blue Ridge provinces.	> 2
2	Abaxial corolla lobes (12–)15–19 mm; mid-cauline leaf blades 53–80(–117) mm; Coastal Plain Province.	Chelone obliqua var. obliqua
2	Abaxial corolla lobes 12–15(–16) mm; mid-cauline leaf blades (60–)80–197 mm; Blue Ridge Province.	Chelone obliqua var. erwiniae