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FNA | Family List | FNA Vol. 26 | Agavaceae | Yucca

22. Yucca arkansana Trelease, Rep. (Annual) Missouri Bot. Gard. 13: 63. 1902.

Arkansas yucca

Yucca angustifolia Pursh var. mollis Engelmann; Y. arkansana var. paniculata McKelvey; Y. glauca Nuttall var. mollis Engelmann ex Branner & Coville

Plants forming small colonies, acaulescent or caulescent; rosettes usually small. Stems decumbent, short, to 0.2 m. Leaf blade mostly yellowish green, flattened, grasslike, concavo-convex, widest near middle, 20–60(–70) × 0.7–2(–2.5) cm, flexible, margins entire, curled, filiferous, apex long, tapering to short spines 1.6–3.2 mm. Inflorescences racemose, occasionally paniculate proximally, arising within rosettes or at rosette level, 3–6(–8) dm, glabrous; bracts erect; peduncle scapelike, 0.2–0.5(–0.6) m, 0.3–0.7(–1.3) cm diam. Flowers pendent; perianth globose; tepals distinct, greenish white, elliptic to orbicular or oblong, 3.2–6.5 × 2–5 cm; filaments 1.3–2.5 cm; anthers 3.2 mm; pistil 2.5–2.8(–3.2) cm; style dark green, 7–13 mm, tumid; stigmas lobed. Fruits erect, capsular, dehiscent, oblong-cylindric to obovoid, constricted near middle, stout, 4–6.5(–7) × 2–3 cm, dehiscence septicidal. Seeds dull black, thin, ca. 1 cm diam.

Flowering spring. Gravelly soil, limestone outcrops, rocky hillsides, prairies; 100--400 m; Ark., Kans., Mo., Okla., Tex.

Yucca arkansana shows considerable variation, particularly in the eastern part of its range. S. D. McKelvey (1938–1947) described var. paniculata and suggested that it is an eastern extension of the species with a taller, paniculate, and pubescent inflorescence. Yucca arkansana approaches Y. louisianensis, which we have reduced to synonymy under Y. flaccida. K. H. Clary’s (1997) DNA consensus tree places Y. arkansana and Y. louisianensis adjacent to one another.


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