Flora of North America species comparison

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Yucca pallida

Yucca harrimaniae

pale yucca, twistleaf yucca

Harriman's yucca, Spanish bayonet
Habit Plants forming loose colonies of rosettes, acaulescent, with branching subterranean caudices; rosettes 10–30 per colony, each rosette with fewer than 100 leaves. Plants cespitose, forming dense to open colonies, acaulescent or short-caulescent; rosettes usually small, asymmetrical or symmetrical.
Stems

to 0.3 m. Leaf blade pale green, linear- or spatulate-lanceolate, concavo-convex, widest near middle, 30–50 × 1.8–4.3 cm, rigid, margins entire, filiferous, white or brown, apex pungent.
Leaf

blade lanceolate, straight, flat except becoming concave near apex, widest above middle, 20–50 × 1–4.5 cm, flexible, glaucous, margins denticulate or sometimes wavy, yellow.

Inflorescences

paniculate, often distally racemose, arising beyond rosettes, 7–12 dm, with wide-spreading branchlets 1.5–2.3 dm;

bracts erect;

peduncle scapelike, 0.6–1.3 m, less than 2.5 cm diam., glaucous.

racemose, rarely paniculate proximally, arising within or just beyond rosettes, 3.5–7 dm;

branches, when present, few, short;

bracts erect, proximal to 20 cm, distal 5–8 cm;

peduncle scapelike, 0.1–0.2 m, less than 2.5 cm diam.
Flowers

pendent;

perianth campanulate;

tepals distinct, greenish white, elliptic to ovate, 5–6.5 × 2–3.2 cm;

filaments 1.8–3.2 cm;

pistil 3.2–4 cm;

style white, 13–20 mm;

stigmas lobed.

pendent;

perianth broadly campanulate;

tepals distinct, yellow or greenish yellow, usually tinged purple, broadly lanceolate, 4–5(–5.3) × 1.6–3.4 cm;

filaments 1.6–2.8 cm;

pistil pale green, 2.7–3.8 × 0.4–0.8 cm;

style pale to bright green, 9–13 mm;

stigmas lobed.
Fruits

erect, capsular, dehiscent, oblong-cylindric, 4.5–5.5 × 1.3–2 cm, dehiscence septicidal.

erect, capsular, dehiscent, cylindrical, usually deeply constricted toward center, 3–5(–5.5) × 2–3 cm, dehiscence septicidal.
Seeds

dull black, thin, 5–7 mm diam.

dull black, thin, 5–8 × (3.5–)4–8 mm.

Yucca pallida

Yucca harrimaniae
Phenology Flowering spring. Flowering spring–early summer.
Habitat Rocky prairies and uplands, rarely limestone hills Desert slopes, foothills, and plateaus in limestone and volcanic outcrops
Elevation 100–400 m (300–1300 ft) 1000–2500 m (3300–8200 ft)
Distribution
from FNA
TX
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; CO; NM; NV; UT
[WildflowerSearch map]
[BONAP county map]
Discussion

Yucca pallida is endemic to the blackland prairies of Texas and was originally included in Y. rupicola. J. M. Webber (1953) indicated that he found plants of Y. rupicola with key features similar to those of Y. pallida. Occasionally, plants with entire margins are found; these have been called Y. pallida var. edentata, which S. D. McKelvey (1938–1947) suggested might be a hybrid between Y. pallida and Y. arkansana. K. H. Clary (1997) indicated that DNA evidence confirms the close relationship of Y. pallida and Y. rupicola.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

S. D. McKelvey (1938–1947) included Yucca neomexicana in Y. harrimaniae, as did J. L. Reveal (1977c), who gave it varietal status. K. H. Clary’s (1997) DNA studies contributed to a consensus tree in which Y. harrimaniae and Y. neomexicana are discrete and widely separated. These taxa are allopatric, separated by the San Juan Mountains of Colorado, and this along with Clary’s evidence supports their recognition as separate species.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 26, p. 431. FNA vol. 26, p. 436.
Parent taxa Agavaceae > Yucca Agavaceae > Yucca
Sibling taxa
Y. aloifolia, Y. angustissima, Y. arkansana, Y. baccata, Y. baileyi, Y. brevifolia, Y. campestris, Y. constricta, Y. elata, Y. faxoniana, Y. filamentosa, Y. flaccida, Y. glauca, Y. gloriosa, Y. harrimaniae, Y. intermedia, Y. madrensis, Y. necopina, Y. neomexicana, Y. reverchonii, Y. rostrata, Y. rupicola, Y. schidigera, Y. tenuistyla, Y. thompsoniana, Y. treculeana, Y. utahensis
Y. aloifolia, Y. angustissima, Y. arkansana, Y. baccata, Y. baileyi, Y. brevifolia, Y. campestris, Y. constricta, Y. elata, Y. faxoniana, Y. filamentosa, Y. flaccida, Y. glauca, Y. gloriosa, Y. intermedia, Y. madrensis, Y. necopina, Y. neomexicana, Y. pallida, Y. reverchonii, Y. rostrata, Y. rupicola, Y. schidigera, Y. tenuistyla, Y. thompsoniana, Y. treculeana, Y. utahensis
Synonyms Y. pallida var. edentata, Y. rupicola var. edentata Y. gilbertiana, Y. harrimaniae var. gilbertiana, Y. harrimaniae var. sterilis
Name authority McKelvey: Yuccas Southw. U.S. 2: 57, plates 13, 14. (1947) Trelease: Rep. (Annual) Missouri Bot. Gard. 13: 59, plates 28, 29, plate 83, fig. 10, plate 93, fig. 1. (1902)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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