Yucca

Yucca is a genus of perennial shrubs and trees in the agave family, Agavaceae. Its 40-50 species are notable for their rosettes of evergreen, tough, sword-shaped leaves and large terminal panicles of white or whitish flowers. They are native to the hot and dry (arid) parts of North America, Central America, South America, and the Caribbean. Early reports of the species were confused with the cassava (Manihot esculenta). Consequently, Linnaeus mistakenly derived the generic name from the Carib word for the latter, yuca. It is also colloquially known in the midwest United States as "Ghosts in the graveyard", as it is commonly found growing in rural graveyards and when in bloom the flowers appear as an apparition floating.
==Distribution==
The natural distribution range of the genus Yucca (49 species and 24 subspecies) covers a vast area of North and Central America. From Baja California in the west, northwards into the southwestern United States, through the drier central states as far north as Alberta in Canada (Yucca glauca ssp. albertana), and moving east along the Gulf of Mexico, and then north again, through the Atlantic coastal and inland neighbouring states.
To the south, the genus is represented throughout Mexico and extends into Guatemala (Yucca guatemalensis). Yuccas have adapted to an equally vast range of climatic and ecological conditions. They are to be found in rocky deserts and badlands, in prairies and grassland, in mountainous regions, in light woodland, in coastal sands (Yucca filamentosa), and even in subtropical and semi-temperate zones, although these are generally arid to semi-arid.
==Ecology==
Yuccas have a very specialized, mutualistic pollination system, being pollinated by yucca moths (family Prodoxidae); the insect purposefully transfers the pollen from the stamens of one plant to the stigma of another, and at the same time lays an egg in the flower; the moth larva then feeds on some of the developing seeds, always leaving enough seed to perpetuate the species. Yucca species are the host plants for the caterpillars of the Yucca Giant-Skipper (Megathymus yuccae), Ursine Giant-Skipper (Megathymus ursus), and Strecker's Giant-Skipper (Megathymus streckeri).
==Uses==
Yuccas are widely grown as ornamental plants in gardens. Many species of yucca also bear edible parts, including fruits, seeds, flowers, flowering stems, and more rarely roots. References to yucca root as food often stem from confusion with the similarly spelled but botanically unrelated yuca, also called cassava (Manihot esculenta). Roots of soaptree yucca (Yucca elata) are high in saponins and are used as a shampoo in Native American rituals. Dried yucca leaves and trunk fibers have a low ignition temperature, making the plant desirable for use in starting fires via friction.
==Cultivation==
Yucca are widely planted in the western US as a landscape plant. Most species are generally heat and cold tolerant, requiring little care and low water. They offer a dramatic accent to a landscape design.
Joshua trees (Yucca brevifolia) are protected by law in some states and should not be wild collected without permit. As a landscape plant, they can be killed by excessive water during their summer dormant phase. For these two reasons they are avoided by landscape contractors.
==Symbolism==
The "yucca flower" is the state flower of New Mexico. No species name is given in the citation.
== Species ==
 		Yucca aloifolia 	Aloe yucca, Spanish Bayonet
 		Yucca angustissima 	Narrowleaf yucca, Spanish Bayonet
 		Yucca brevifolia 	Joshua tree
 		Yucca constricta 	Buckley's yucca
 		Yucca baccata 	Banana yucca, datil
 		Yucca decipiens 	Palma China
 		Yucca elata 	Soaptree yucca
 		Yucca filamentosa 	Spoonleaf yucca, Filament yucca, or Adam's Needle
 		Yucca filifera 	Palma Chuna yucca
 		Yucca flaccida 	Flaccid leaf yucca
120px		Yucca glauca 	Great Plains yucca
 		Yucca gloriosa 	Moundlily yucca, Adam's needle, Spanish Dagger
 		Yucca grandiflora 	Sahuiliqui yucca
120px		Yucca guatemalensis	Spineless yucca
 		Yucca harrimaniae 	Harriman's yucca
 		Yucca intermedia 	Intermediate Yucca
 		Yucca jaliscensis 	Izote
 		Yucca kanabensis 	Kanab yucca
 		Yucca lacandonica 	Tropical yucca
 		Yucca madrensis 	Soco yucca
 		Yucca nana 	Dwarf yucca
 		Yucca pallida 	Pale yucca
 		Yucca periculosa 	Izote
 		Yucca recurvifolia 	Curve-leaf yucca
 		Yucca rigida 	Blue yucca
 		Yucca rostrata 	Beaked yucca, Big Bend yucca
 		Yucca rupicola 	Texas yucca, or Twist-leaf yucca
 		Yucca schidigera 	Mojave yucca
 		Yucca schottii 	Hoary yucca or Mountain yucca
 		Yucca standleyi 	
 		Yucca thompsoniana 	Thompson's Yucca
 		Yucca thornberi 	
 		Yucca torreyi 	Torrey yucca
 		Yucca treculiana 	Texas bayonette, Trecul's yucca
 		Yucca valida 	Datilillo
 		Yucca yucatana 	Yucatan yucca
A number of other species previously classified in Yucca are now classified in the genera Dasylirion, Furcraea, Hesperaloe, Hesperoyucca and Nolina.
==Taxonomic arrangement==
*Section Yucca formerly Sarcocarpa Engelm.
**Series Faxonianae Hochstätter
***Yucca carnerosana (Trel.) McKelvey
***Yucca faxoniana (Trel.) Sarg.
**Series Baccatae Hochstätter
***Yucca baccata Torr.
****Yucca baccata Torr. ssp. baccata
****Yucca baccata Torr. ssp. vespertina (McKelvey) Hochstätter
****Yucca baccata Torr. ssp. thornberi (McKelvey) Hochstätter
***Yucca confinis McKelvey
***Yucca endlichiana Trel.
***Yucca arizonica McKelvey
**Series Treculianae Hochstätter
***Yucca grandiflora Gentry
***Yucca declinata Laferr.
***Yucca treculiana Carriere
***Yucca torreyi Shafer
***Yucca schidgera Roezl ex Ortgies
***Yucca schotti Engelm.
***Yucca capensis Lenz
***Yucca jaliscensis Trel.
***Yucca periculosa Baker
***Yucca mixtecana Garcia-Mend.
***Yucca decipiens Trel.
***Yucca valida Brandegee
***Yucca potosina Rzed.
***Yucca filifera Chabaud
**Series Gloriosae Hochstätter
***Yucca gloriosa L.
***Yucca recurvifolia Salisb.
**Series Yucca
***Yucca madrensis Gentry
***Yucca linearifolia Clary
***Yucca elephantipes Regel
***Yucca lacandonica Gomez-Pompa & Valdes
***Yucca aloifolia L.
***Yucca yucatana Engelm.
*Section Clistocarpa Engelm.
***Yucca brevifolia Engelm.)
****Yucca brevifolia Engelm. ssp. brevifolia
****Yucca brevifolia Engelm. ssp. jaegeriana (McKelvey) Hochstätter
****Yucca brevifolia Engelm. ssp. herbertii (Webber) Hochstätter
*Section Chaenocarpa Engelm.
**Series Filamentosae Hochstätter
***Yucca filamentosa L.
****Yucca filamentosa L. ssp. filamentosa
****Yucca filamentosa L. ssp. smalliana (Fernald) Hochstätter
****Yucca filamentosa L. ssp. concava (Haw.) Hochstätter
***Yucca flaccida Haw.
**Series Rupicolae Hochstätter
***Yucca cernua Keith
***Yucca pallida McKelvey
***Yucca queretaroensis Pina Lujan
***Yucca reverchonii Trel.
***Yucca rigida (Engelm.) Trel.
***Yucca rostrata Engelm. ex Trel.
***Yucca rupicola Scheele
***Yucca thompsoniana Trel.
**Series Harrimaniae Hochstätter
***Yucca harrimaniae Trel.
****Yucca harrimaniae Trel. ssp. harrimaniae
****Yucca harrimaniae Trel. ssp. neomexicana (Wooton & Standl.) Hochstätter
****Yucca harrimaniae Trel. ssp. sterilis (Neese & Welsh) Hochstätter
****Yucca harrimaniae Trel. ssp. gilbertiana (Trel.) Hochstätter
***Yucca nana Hochstätter
**Series Glaucae (McKelvey) Hochstätter
***Yucca angustissima Engelm. ex Trel.
****Yucca angustissima Engelm. ex Trel. ssp. angustissima
****Yucca angustissima Engelm. ex Trel. ssp. toftiae (Welsh) Hochstätter
****Yucca angustissima Engelm. ex Trel. ssp. kanabensis (McKelvey) Hochstätter
****Yucca angustissima Engelm. ex Trel. ssp. avia (Reveal) Hochstätter
***Yucca baileyi Wooton & Standl.
****Yucca baileyi Wooton & Standl. ssp. baileyi
****Yucca baileyi Wooton & Standl. ssp. intermedia (McKelvey) Hochstätter
***Yucca coahuilensis Matuda & Pinja Lujan
***Yucca elata Engelm.
****Yucca elata Engelm. ssp. elata
****Yucca elata Engelm. ssp. utahensis (McKelvey) Hochstätter
****Yucca elata Engelm. ssp. verdiensis (McKelvey) Hochstätter
***Yucca glauca Nutt.
****Yucca glauca Nutt. ssp. glauca
****Yucca glauca Nutt. ssp. stricta (Sims) Hochstätter
****Yucca glauca Nutt. ssp. albertana Hochstätter
***Yucca campestris McKelvey
***Yucca constricta Buckley
***Yucca arkansana Trel.
****Yucca arkansana Trel. ssp. arkansana
****Yucca arkansana Trel. ssp. louisianensis (Trel.) Hochstätter
****Yucca arkansana Trel. ssp. freemanni (Shinners) Hochstätter
*Section Hesperoyucca Engelm.
***Yucca whipplei Torr.
****Yucca whipplei Torr. ssp. whipplei
****Yucca whipplei Torr. ssp. caespitosa (Jones) Haines
****Yucca whipplei Torr. ssp. intermedia Haines
****Yucca whipplei Torr. ssp. percursa Haines
****Yucca whipplei Torr. ssp. newberryi (McKelvey) Hochstätter
****Yucca whipplei Torr. ssp. eremica Epling & Haines
==Cultivars==
In the years from 1897 to 1907, Carl Ludwig Sprenger created and named 122 Yucca hybrids.
== References ==
Category:Yucca