Yucca arkansana

Trelease

Rep. (Annual) Missouri Bot. Gard. 13: 63. 1902.

Common names: Arkansas yucca
Endemic
Synonyms: Yucca angustifolia var. mollis Engelmann Yucca arkansana var. paniculata McKelvey Yucca glauca var. mollis Engelmann ex Branner & Coville
Treatment appears in FNA Volume 26. Treatment on page 436. Mentioned on page 426, 431, 437, 438.

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.


Phenology: Flowering spring.
Habitat: Gravelly soil, limestone outcrops, rocky hillsides, prairies
Elevation: 100–400 m

Distribution

V26 902-distribution-map.jpg

Ark., Kans., Mo., Okla., Tex.

Discussion

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.

Selected References

None.

Lower Taxa

None.

"thick" is not a number. "thin" is not a number."dm" is not declared as a valid unit of measurement for this property."dm" is not declared as a valid unit of measurement for this property. "dm" is not declared as a valid unit of measurement for this property."thin" is not a number.

... more about "Yucca arkansana"
longitudinal +
3.2 cm32 mm <br />0.032 m <br /> (?) +
glandular-pubescent +  and glandular +
tapering +
William J. Hess +  and R. Laurie Robbins +
Trelease +
elliptic +, ovate +, oblanceolate +, lanceolate +  and linear +
expanded +
fleshy +  and rigid +
scale-like +
Arkansas yucca +
Ark. +, Kans. +, Mo. +, Okla. +  and Tex. +
100–400 m +
elongated +
pubescent +  and glabrous +
flattened +
1.3 cm13 mm <br />0.013 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
broadened +
septicidal +, 2cm +  and 3cm +
oblong-cylindric +  and obovoid +
constricted +
fleshy +  and dry +
Gravelly soil, limestone outcrops, rocky hillsides, prairies +
paniculate +  and racemose +
60 cm600 mm <br />0.6 m <br /> (70 cm700 mm <br />0.7 m <br />) +
2 cm20 mm <br />0.02 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
yellowish green +
20 cm200 mm <br />0.2 m <br /> (60 cm600 mm <br />0.6 m <br />) +
concavo-convex +  and flattened +
long-lived +  and annual +
0.7cm;2cm +
6-lobed +
not +  and articulate +
50 cm500 mm <br />0.5 m <br /> (60 cm600 mm <br />0.6 m <br />) +
0.3 cm3 mm <br />0.003 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +
20 cm200 mm <br />0.2 m <br /> (50 cm500 mm <br />0.5 m <br />) +
semisucculent +
Flowering spring. +
2.8 cm28 mm <br />0.028 m <br /> (3.2 cm32 mm <br />0.032 m <br />) +
oblong-cylindrical +  and obovoid +
2.5 cm25 mm <br />0.025 m <br /> (2.8 cm28 mm <br />0.028 m <br />) +
Rep. (Annual) Missouri Bot. Gard. +
0 cm0 mm <br />0 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
ovate +, obovate +, round +  and flattened +
0.16 cm1.6 mm <br />0.0016 m <br /> (0.32 cm3.2 mm <br />0.0032 m <br />) +
exserted +  and included +
aboveground +  and subterranean +
0 cm0 mm <br />0 m <br /> (20 cm200 mm <br />0.2 m <br />) +
white;pale green +
1 +  and 3 +
0.1 cm1 mm <br />0.001 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
exserted +  and included +
0.7 cm7 mm <br />0.007 m <br /> (1.3 cm13 mm <br />0.013 m <br />) +
Yucca angustifolia var. mollis +, Yucca arkansana var. paniculata +  and Yucca glauca var. mollis +
Yucca arkansana +
species +
greenish white +
distinct +
3.2cm +  and 6.5cm +
elliptic +  and orbicular or oblong +
2cm;5cm +
caulescent +  and acaulescent +
aboveground +  and subterranean +
polygamodioecious +, dioecious +, monoecious +, polycarpic +  and monocarpic +
small;gigantic +
petal-like +