Yucca gloriosa

Yucca gloriosa is a species of flowering plant in the family Asparagaceae, native to the southeastern United States. Growing to , it is an evergreen shrub. It is widely cultivated as an ornamental for its architectural qualities, and has reportedly become established in warmer climates in the wild in various parts of the world. 
Names.
Common names include:-
Description.
"Yucca gloriosa" is , usually with several stems arising from the base, the base thickening in adult specimens. The long narrow leaves are straight and very stiff, growing to long and wide. They are dark green with entire margins, smooth, rarely finely denticulate, acuminate, with a sharp brown terminal spine. The inflorescence is a panicle up to long, of bell-shaped white flowers, sometimes tinged purple or red. The fruit is a leathery, elongate berry up to long.
Habitat.
"Yucca gloriosa" grows on exposed sand dunes along the coast and barrier islands of the subtropical southeastern USA, often together with "Yucca aloifolia" and a variety formerly called "Yucca recurvifolia" or "Y. gloriosa" var. "recurvifolia", now "Y. gloriosa" var. "tristis". In contrast to "Y. gloriosa" var. "tristis", the leaves of "Y. gloriosa" var. "gloriosa" are hard stiff, erect and narrower. On the other hand, "Y. aloifolia" has leaves with denticulate margins and a sharp-pointed, terminal spine.
Distribution.
"Yucca gloriosa" is native to the coast and barrier islands of southeastern North America, growing on sand dunes. It ranges from extreme southeastern Virginia south to northern Florida in the United States. It is associated with "Yucca filamentosa", "Yucca aloifolia", and "Opuntia" species.
Cultivation.
The plant is widely cultivated in warm temperate and subtropical climates, and valued as an architectural focal point. It has reportedly escaped from cultivation and naturalised in Italy, Turkey, Mauritius, Réunion, Guam, the Northern Mariana Islands, Puerto Rico, Argentina, Chile and Uruguay.
In a domestic environment, the plant has average water requirements, and little maintenance is needed other than the removal of dead leaves when the shrub nears its ultimate height. The plant is very hardy, without leaf damage at , and can handle occasional snow and freezing temperatures.
"Yucca gloriosa", and the cultivars 'Variegata' and = ‘Walbristar’ have gained the Royal Horticultural Society's Award of Garden Merit.
Properties.
"Yucca gloriosa" has been known to cause skin irritation and even allergic reactions upon contact. The leaf points are even sharp enough to break the skin.
Forms and varieties.
In collections in Europe and overseas, there are many forms and hybrids (Sprenger, Förster) from the 18th and 19th centuries. The following names have been used for material of uncertain origin in the European garden flora.