Yucca or Adam's Needle

(Agavaceae - Agave Family)

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• Form
  • short- to medium-sized evergreen ornamental "shrub"
  • evergreen foliage forms a clump maturing at 2.5' tall by 2.5' wide, but the annual woody inflorescences bolt up to 8' tall
  • radiating clump growth habit
  • slow growth rate of spread, but a rapid growth rate for the annual upright inflorescences

• Culture
  • full sun to full shade
  • performs best in full sun in moist, well-drained, deep soils, but it is extremely urban tolerant, including tolerance to poor soils, various soil pHs, soil compaction, heat, high light reflextion, extended drought, pollution, and Winter salt spray; however, it does not tolerate poor drainage or wet sites, and does not bloom in full shade
  • propagated primarily by root segments and clump division, but also by seeds
  • Agave Family, with few disease or pest problems
  • abundantly available in container form
  • the flowering stalk should be dead-headed (pruned away, all the way to the ground) after flowering is finished, as the fruiting stalk is unsightly and will persist for two or three years as "dead wood" unless it is removed
  • Yuccas have many deep tap roots, and are extremely difficult to completely remove by digging out; in fact, this serves as a method of propagation, as many miniature Yuccas will return in a couple of months or the next year from the remaining or broken root segments; in this case, repeated applications of herbicide are needed for control

• Foliage
  • medium green, glaucous, evergreen, sword-like, radiating from ground-level fibrous stems, and bending downwards with age
  • lanceolate and slightly concave leaves are each to 2.5' long, with veins that are parallel along the length of the blade
  • margins have exfoliating white threads (hence the specific epithet)

• Flowers
  • creamy-white conical inflorescences range from 3' to 8' tall, blooming during July and August, and are quite showy when in flower
  • individual flowers hang downwards, with petals that resemble huge teeth emerging from the corolla, and bloom from the bottom to the top of the semi-woody inflorescences

• Fruits
  • the chartreuse fruit capsules occur along the persistent upright stalks, maturing to brown in early Autumn if left alone, but best pruned away for neatness and to promote the superior evergreen foliage effect

• Twigs
  • the very short, fibrous, semi-woody to pulpy stems occur at ground level and are hidden by the dense evergreen foliage

• Trunk
  • not applicable

• ID Summary
  • sword-like foliage with thready margins radiates from the hidden ground-level stems on this evergreen clump of "shrub", with very tall inflorescences having creamy-white mid-Summer flowers on thick, many-branched spires of semi-woody stems

• Function
  • a bold evergreen focal point in the landscape, either in group plantings or solitary, used at entranceways, borders, rock gardens, island beds, or as a specimen accent

• Texture
  • bold texture in foliage, flower, and fruit
  • thick density for the evergreen foliage, and open density for the large inflorescences

• Assets
  • evergreen foliage
  • extremely urban tolerant (especially to heat, drought, and blazing sun exposure)
  • Winter salt spray tolerant

• Liabilities
  • dead basal foliage needs to be carefully removed with a sharp knife in early Spring (wear gloves; the tough foliage can be sharp on its edges, in addition to the knife), and immature fruiting stalks are best pruned away just after flowering has finished in mid-Summer, to keep the plant tidy
  • removal by digging entails follow-up with several applications of weed killer, as the remaining root segments will sprout within weeks or in the following year

• Habitat
  • zones 4 to 9
  • native to the Southeastern United States (although it is often planted for a "Southwestern" xeriscape look)

• Alternates
  • striking bold-textured perennials (Acanthus spinosus, Hibiscus moscheutos, Opuntia humifusa, Peltiphyllum peltatum, Petasites japonicus, Rheum palmatum, Rudbeckia laciniata, etc.), biennials (Angelica archangelica, Heracleum mantegazzianum, etc.), or annuals (Caladium, Canna, Coleus, Dahlia, Datura inoxia, Helianthus annuus, Ricinus communis, etc.)
  • shrubs of unusual character, to complement ultra-modern interior decor (Abies koreana 'Horstmann's Silberlocke', Aralia spinosa, Corylus avellana 'Contorta', Cytisus, Picea pungens glauca 'Blue Totem', Pinus strobus 'Pendula', Salix matsudana 'Tortuosa', Tsuga canadensis 'Sargentii', etc.)
  • true southwestern accent plants (basically members of the Cactus Family and similar families)

• Variants
  • there are several species of Yucca, and some of the cultivars below may acutally belong to other species, although commonly associated with Yucca filamentosa
  • Yucca filamentosa 'Bright Edge' - green foliage with a clearly demarcated thin yellow margin, less prone to reversion to the green foliaged-form
  • Yucca filamentosa 'Color Guard' - a better substitute for "Golden Sword', having a more crisply defined yellow stripe running down the center of the blade
  • Yucca filamentosa 'Golden Sword' - green-margined foliage has broad and ill-defined yellow streaks in the center of the leaf blade, but subsequent lateral shoots are prone to reversion to the natural green-foliaged form
  • Yucca filamentosa 'Hofer Blue' - foliage is distinctly glaucous and blue-silver to blue-green in Spring, fading to green-blue in Winter

NOTES

• Translation
  • Yucca is the Caribbean name for Cassava, originally misidentified as another species of Yucca.
  • filamentosa translates as "with filaments," referring to the thready leaf margins.

• Purpose
  • Yucca is a representative of the xeric "Southwestern-accent" landscape plants (even though it is native to the southeastern United States).

• Summary
  • Yucca filamentosa is an evergreen, drought-hardy, bold focal point foliage plant with a radiating "Southwestern Look", also having prominent flowering stalks in mid-Summer.