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Yucca rigida

(Silver Leaf Yucca)

Common Names

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Common Names in English:

Blue Yucca, Palmilla, Silver Leaf Yucca

Description

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Family Agavaceae

Plants usually perennial , occasionally epiphytic, sometimes monocarpic or polycarpic, monoecious, dioecious, or polygamodioecious, small to gigantic, sometimes arborescent , usually scapose . Stems subterranean or aboveground, sometimes branched. Leaves simple , annual or long-lived, in terminal rosettes or occasionally cauline, sessile or occasionally pseudo-petiolate; blade linear , lanceolate, oblanceolate , ovate , or elliptic , fibrous , thin and flexible , thick and rigid or succulent, or fibrous, often glaucous, margins entire, serrulate , dentate , denticulate , corneous , or filiferous , apex rigid or flexible, sometimes pungent , often with short or long spine. Inflorescences terminal or axillary spikes, racemose or paniculate , sometimes umbellate , bracteate , often huge; bracts ascending or erect , occasionally reflexed , leaflike proximally, scalelike distally. Flowers 6-merous, bisexual or functionally unisexual ; perianth of 2 similar petallike whorls, semisucculent; tepals distinct or connate into tube , apex glandular or glandular-pubescent ; stamens included or exserted; filaments often broadened and succulent, glabrous , pubescent , or papillose ; anthers versatile, dehiscence longitudinal ; ovary superior or inferior, 3-locular or occasionally 1-locular, 3-angled, ovoid , or cylindrical, with axillary or rarely parietal placentation ; style included or exserted; stigmas 1 or 3, 3-lobed or capitate; pedicel usually distinct, articulate or not, rarely absent. Fruits occasionally baccate , usually capsular and sometimes winged or lobed , or indehiscent and dry or fleshy . Seeds 1€“3(€“many) per locule, flattened, 3-angled, hemispheric , ovoid, obovoid , or globose .

Genera 17 or 18, species ca. 550 (9 genera, 84 species in the flora ; 2 genera, 6 species introduced) : worldwide, primarily arid , semitropical, subtropical , and tropical regions .

There is little agreement on the treatment of Agavaceae. The group containing Agave, Yucca, Furcraea, Hesperaloe, and Manfreda generally has been accepted as the core of Agavaceae, or as subfamilies Agavoideae and Yuccoideae, but treatment of Dracaena, Sansevieria, Cordyline, Nolina, and Dasylirion has been varied. A. L. Takhtajan (1987) and R. F. Thorne (1992b) placed these genera in Dracaenaceae but treated them at different levels. Takhtajan located them in the subfamily Dracaenoideae within sections Nolineae (Nolina and Dasylirion), Sansevierieae (Sansevieria), and Dracaeneae (Cordyline and Dracaena) . Thorne, on the other hand, placed these same groupings at the subfamily level. R. M. T. Dahlgren et al. (1985) recognized them as separate families, Nolinaceae (Nolina and Dasylirion), Dracaenaceae (Sansevieria and Dracaena), and Asteliaceae (Cordyline), in addition to the Agavaceae (Yucca, Hesperaloe, Agave, Manfreda, and Furcraea) .

A. Cronquist (1981) based his broadly circumscribed Agavaceae on a common xerophytic habit. However, the karyotype of 5 long and 25 short chromosomes for the Agavoideae and Yuccoideae is distinct from the karyotypes of the other subfamilies that Cronquist included in the Agavaceae. Current research on the phylogenetics of moncotyledons, using DNA sequences of rbcL , support the separation of Dracaena, Nolina, and Dasylirion from Agavaceae (M. R. Duvall et al. 1993b) . We believe that a broad interpretation of the Agavaceae unites groups that should be recognized as separate.

Many genera in Agavaceae are economically important. All genera in the Agavoideae and Yuccoideae contain steroidal sapogenins ; some have been used in folk medicine, and locally and commercially as soap (G. Blunden et al. 1978; S. E. Verhoek 1978; M. Wall et al. 1957) . They provide fibers for cordage, baskets, and hats, as well as food and drink for many indigenous peoples of the southwestern United States (H. S. Gentry 1982) . They are also used as commercial fiber and beverage crops in Latin America and the Old World (H. Brucher 1989) . In the southern United States, some species in each genus are cultivated and represented in the flora, and at least one species of Yucca is now grown as far north as Canada. Collectors should record the uses of these plants in their notes along with the critical information on plant habit and morphology. Photographs are often important tools for the identification of these plants, and, with the advent of digital cameras , are now much easier to obtain and process .[1]

Genus Yucca

Plants perennial , acaulescent or caulescent , sometimes subscapose , sometimes arborescent , usually branching extensively, from woody, subterranean or aboveground caudices, or single stems. Leaves sessile, in rosettes on caudices or at branch ends; blade linear-lanceolate, expanded basally, usually rigid , occasionally fleshy , margins entire or denticulate , often filiferous and separating into elongated fibers, corneous , apex mostly sharp-pointed. Scape, when present, usually less than 2.5 cm diam. Inflorescences erect or rarely pendent, paniculate or racemose, sometimes paniculate proximally and racemose distally, bracteate , occasionally pubescent ; bracts ascending , erect, or rarely reflexed ; peduncle sometimes scapelike, sometimes extending beyond leaves, sometimes pubescent. Flowers bisexual ; perianth campanulate or globose ; tepals 6, similar, fleshy, distinct to or connate at base , whitish to cream or tinged slightly with green or purple, occasionally pubescent; stamens 6; filaments flattened, as wide as anthers , smooth , papillose , or granular , fleshy; pistil obovoid or oblong-cylindrical; ovary superior, usually green, 3-locular or 6-locular with false septa, 6-lobed; style white to dark green, often thick; stigmas usually 3, sometimes 1 and subcapitate , white to pale green, 1-2 mm. Fruits erect or pendent, capsular or baccate . Seeds many per locule, usually black, occasionally gray, flattened, round, rarely obovate or ovate . x = 25, 30.

Species ca. 35-40: e coastal plain , se, sc, w United States, n, c, w Mexico, n Central America.

W. Trelease (1902) recognized Hesperoyucca, Clistoyucca, and Samuela as segregates from, but closely related to, Yucca. S. D. McKelvey (19381947) returned them to Yucca, recognizing sections Hesperoyucca and Clistoyucca, and placing Samuela in section Sarcocarpa. However, McKelvey indicated that there is ample justification for recognizing Hesperoyucca at genus level, since a number of flower and fruit characters differ from those in all other sections. Recent DNA evidence provides strong support for separate recognition of Hesperoyucca (M. A. Hanson 1993; D. J. Bogler 1994; D. J. Bogler and B . B. Simpson 1995, 1996; K . H. Clary 1997). Clarys data indicate that it is more closely related to Hesperaloe than to Yucca, and that Clistoyucca and Samuela should be retained in Yucca.

Yuccas are often cultivated in many places in the United States, particularly in the south. They are not easily identified, particularly in herbarium specimens, and collectors should be certain to record information about the habits and sizes of plants, and the colors of ovaries, styles, and stigmas. If possible, field photographs of the pistil and stamens should accompany the specimens.[2]

Physical Description

Habit: Evergreen .

Flowers: Bloom Period: March. • Flower Color: cream, tan

Size/Age/Growth

Size: 12-15' tall.

Biology

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Growth

Culture: Space 36-48" apart.

Sunlight: Sun Exposure: Full Sun .

Moisture: Drought Tolerance: High

Temperature: Cold Hardiness: 7b, 8a, 8b, 9a, 9b, 10a, 10b. (map)

Taxonomy

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Unambiguous Synonyms

  1. Yucca Rupicola Rigida

Notes

Publishing author : Trel. Publication : Rep. (Annual ) Missouri Bot. Gard. 1902, 65.An accepted name in the RHS Horticultural Database.

Similar Species

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Members of the genus Yucca

ZipcodeZoo has pages for 343 species, subspecies, varieties, forms, and cultivars in this genus. Here are just 100 of them:

Y. acaulis · Y. acrotricha · Y. acuminata · Y. acutifolia · Y. agavoides · Y. albo-spica · Y. aletriformis · Y. aloifolia (Spanish Bayonet) · Y. aloifolia f. marginata · Y. aloifolia 'Marginata' · Y. aloifolia L. 'Marginata' (Variegated Spanish Bayonet) · Y. aloifolia 'Purpurea' · Y. aloifolia 'Spanish Bayonet' · Y. aloifolia 'Tricolor' · Y. aloifolia var. arcuata · Y. aloifolia var. draconis · Y. aloifolia var. yucatana · Y. aloifolia 'Variegata' · Y. aloifolia var. mediopicta · Y. gloriosa var. recurvifolia · Y. angustifolia var. elata · Y. angustifolia var. mollis · Y. angustifolia var. radiosa · Y. angustissima (Narrow-Leaved Yucca) · Y. angustissima Engelm. ex Trel. var. angustissima · Y. angustissima avia · Y. angustissima var. angustissima (Narrowleaf Yucca) · Y. angustissima var. avia · Y. angustissima var. kanabensis (Kanab Yucca) · Y. angustissima var. toftiae (Toft's Yucca) · Y. antwerpensis · Y. arborescens · Y. arcuata · Y. argospatha · Y. argyrophylla · Y. arizonica · Y. arkansana (Arkansas Yucca) · Y. armata · Y. aspera · Y. atkinsi · Y. australis · Y. australis var. valida · Y. baccata (Fleshy-Fruited Yucca) · Y. baccata Torr. var. baccata Torr. · Y. baccata macrocarpa · Y. baccata var. australis · Y. baccata var. baccata (Banana Yucca) · Y. baccata var. brevifolia (Spanish Dagger) · Y. baccata var. vespertina (Banana Yucca) · Y. baccata vespertina · Y. baileyi (Navajo Yucca) · Y. baileyi Wooton & Standl. var. baileyi · Y. baileyi var. navajoa (J.M.Webber) J.M.Webber · Y. baileyi var. baileyi (Bailey's Yucca) · Y. baileyi var. intermedia (Intermediate Yucca) · Y. baileyi var. navajoa (Navajo Yucca) · Y. barrancasecca · Y. boerhaavii · Y. boscii · Y. brevifolia (Joshua Tree) · Y. brevifolia f. herbertii (Joshua Tree) · Y. brevifolia herbertii (Joshua Tree) · Y. brevifolia jaegeriana · Y. brevifolia jaegeriana var. jaegeriana (Jaeger's Joshua Tree) · Y. brevifolia var. brevifolia (Joshua Tree) · Y. brevifolia var. jaegeriana (Jaeger's Joshua Tree) · Y. 'Bright Star' · Y. californica · Y. campestris (Plains Yucca) · Y. canaliculata · Y. capensis · Y. carnerosana (Giant Spanish Dagger) · Y. cernua (Nodding Yucca) · Y. circinata · Y. coahuilensis · Y. concava · Y. conspicua · Y. constricta (Buckley's Yucca) · Y. contorta · Y. cornuta · Y. crassifila · Y. crenulata · Y. crinifera · Y. de-smetiana · Y. decipiens (Palma China) · Y. declinata · Y. desmetiana (Yucca) · Y. draco · Y. draconis · Y. draconis var. arborescens · Y. ehrenbergii · Y. elata (Soap-Tree Yucca) · Y. elata utahensis (Utah Yucca) · Y. elata var. elata (Soaptree Yucca) · Y. elata var. utahensis (Utah Yucca) · Y. elata var. verdiensis (Soaptree Yucca) · Y. elata Engelm. var. verdiensis (McKelvey) Reveal (Soaptree Yucca) · Y. eleana · Y. elegans · Y. elephantipes

More Info

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Further Reading

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Notes

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Contributors

Data Sources

Accessed through GBIF Data Portal December 31, 2007:

Identifiers

Footnotes

  1. Susan Verhoek & William J. Hess "Agavaceae". in Flora of North America Vol. 26 Page 15, 17, 18, 19, 20, 21, 51, 303, 413, 414. Oxford University Press. Online at EFloras.org. [back]
  2. William J. Hess & R. Laurie Robbins "Yucca". in Flora of North America Vol. 26 Page 413, 414, 423, 424, 437, 440. Oxford University Press. Online at EFloras.org. [back]
Last Revised: 2009-07-03