Flora of North America species comparison

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Yucca rostrata

Yucca necopina

beak yucca, izote kikapú

Brazos River 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 cespitose, forming small colonies of rosettes, acaulescent or caulescent; rosettes usually small, each with ca. 50–85 leaves.
Stems

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

erect, to 0.4 m. Leaf blade erect, proximal becoming reflexed, slightly twisted, plano-convex, widest near middle, 50–80 × (1.5–)2–4 cm, rigid, margins entire, filiferous, white, apex acicular.
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, racemose distally or entirely, beginning mostly beyond rosettes, ovoid, 50–120 cm, glabrous;

proximal branches to 15 cm;

bracts erect, distal reduced;

peduncle 0.8–1.6 m, less than 2.5 cm diam.
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.

pendent;

perianth globose;

tepals greenish white, 4–4.5  1.5–3 cm;

filaments 12–15 mm, shorter than pistil;

pistil 1.5–3.8 cm;

stigmas lobed.
Fruits

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

erect, capsular, dehiscent, not conspicuously constricted, dehiscence septicidal.

Yucca rostrata

Yucca necopina
Phenology Flowering spring. Flowering spring.
Habitat Rocky mountain slopes, canyon bottoms River terraces, deep sand
Elevation 700 m (2300 ft) 200–300 m (700–1000 ft)
Distribution
from FNA
TX; n Mexico (Coahuila)
[WildflowerSearch map]
from FNA
TX
[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.)

Yucca necopina was originally described based only on plants from a single locality in Somervell County. Shinners’ sketchy description compared it with Y. arkansana, and he suggested that it might be a hybrid between Y. pallida and Y. arkansana. More recently, G. M. Diggs et al. (1999) reported new locations of Y. necopina from Hood, Parker, and Tarrant counties, and noted that molecular evidence provided to them by K. H. Clary supports its separate recognition.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 26, p. 430. FNA vol. 26, p. 438.
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. gloriosa, Y. harrimaniae, Y. intermedia, Y. madrensis, Y. neomexicana, Y. pallida, Y. reverchonii, Y. rostrata, Y. rupicola, Y. schidigera, Y. tenuistyla, Y. thompsoniana, Y. treculeana, Y. utahensis
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) Shinners: Spring Fl. Dallas-Fort Worth, 91, 408. (1958)
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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