Flora of North America species comparison

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Yucca rostrata

Yucca gloriosa

beak yucca, izote kikapú

moundlily yucca
Habit Plants solitary or forming colonies of rosettes, caulescent, arborescent, 2.5–3.6 m, not including inflorescence, 1.8–3.2 dm diam; rosettes each with more than 100 leaves. Plants forming colonies of rosettes, caulescent, arborescent, simple or more often branching.
Stems

1–several, erect, mostly simple, occasionally 1–3-branched.

erect, to 5 m. Leaf blade erect or recurving, green or blue-green, lanceolate or sword-shaped, flattened, concave distally, thin, 40–100 × 3.5–6 cm, rigid or flexible, glaucous at least when young, margins entire or roughly and minutely denticulate, often becoming filiferous with straight fibers, yellow or brown, opaque.
Leaf

blade linear, often twisted, flat to concavo-convex, widest considerably beyond middle, 25–60 × 1.2–1.7 cm, glaucous, smooth, margins minutely denticulate, lemon yellow, hyaline, apex spinose, spine tipped.

Inflorescences

paniculate, arising just within or beyond rosettes, ovoid, 3–10 dm;

branches up to 3.8 dm;

bracts erect;

peduncle sometimes scapelike, 0.3–1 m, less than 2.5 cm diam., glabrous or glabrescent.

paniculate, arising partly within to well beyond rosettes, ovoid to ellipsoid, 5–12 × 4.5 dm, glabrous or pubescent;

peduncle scapelike, 0.9–1.5 m. Flowers pendent;

perianth globose to campanulate;

tepals distinct, white to creamy white or greenish white, sometimes tinged with purple, elliptic to narrowly ovate, 4–5 × 2–2.5 cm;

filaments ca. 2.6 cm, hispid or slightly papillose;

anthers ca. 3.5 mm;

pistil light green, ca. 3.6 cm;

ovary sessile, ca. 2.8 cm;

style ca. 9 mm;

stigmas separate;

pedicel to 2 cm, often arching.
Flowers

pendent;

perianth globose to campanulate;

tepals distinct, white, narrowly ovate, 4.2–5.2 × 1.1–2 cm, apex sharply acuminate;

filaments 1.7–2 cm;

pistil 2.5–3.5 cm;

style white, 6–14 mm;

stigmas lobed.

Fruits

erect, capsular, dehiscent, ovoid to ellipsoid, rarely constricted, 4–7 × 1.8–2.5 cm, dehiscence septicidal.

erect or pendent, baccate, with core, indehiscent, 6-winged or 6-ribbed, elongate, 2.5–8 cm, leathery.
Seeds

black, lustrous, ovate, thin, 5–8 mm diam. 2n = 50.

Yucca rostrata

Yucca gloriosa
Phenology Flowering spring.
Habitat Rocky mountain slopes, canyon bottoms
Elevation 700 m (2300 ft)
Distribution
from FNA
TX; n Mexico (Coahuila)
[WildflowerSearch map]
from USDA
se United States
[WildflowerSearch map]
[BONAP county map]
Discussion

In the United States, Yucca rostrata is restricted to Brewster County, Texas. It is closely related to Y. thompsoniana (K. H. Clary 1997), which is perhaps just a northern variant of this species.

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

Varieties 2 (2 in the flora).

Yucca gloriosa has a growth habit similar to that of Y. aloifolia, except that the former appears more moundlike due to the terminal branching mode, whereas the latter appears more open because the branching is more median on the trunk.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Key
1. Leaf blade mostly erect, rigid; inflorescences extending well beyond rosettes; berries pendent, 5.5–8 cm.
var. gloriosa
1. Leaf blade mostly recurving, flexible; inflorescences barely extending beyond rosettes; berries mostly erect, 2.5–4.5 cm.
var. recurvifolia
Source FNA vol. 26, p. 430. FNA vol. 26, p. 429.
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. pallida, Y. reverchonii, 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. harrimaniae, 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
Subordinate taxa
Y. gloriosa var. gloriosa, Y. gloriosa var. recurvifolia
Synonyms Y. rostrata var. linearis
Name authority Engelmann ex Trelease: Rep. (Annual) Missouri Bot. Gard. 13: 68, plates 40–42, plate 84, fig. 3, plate 93, fig. 2. (1902) Linnaeus: Sp. Pl. 1: 319. (1753)
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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