Peculiar Plants of our Area: The Chaparral Yucca

Chaparral Yuccas (Hesperoyucca whipplei)

If you have been hitting the trails recently, it is likely you have come across a plant with a towering white stalk of flowers, reaching twice your height or more. These impressive inflorescences belong to the Chaparral Yucca, more nobly known as “Our Lord’s Candle”, or Hesperoyucca whipplei in the scientific sense. Classified as an agave in the asparagus family, this sharp-leaved, unusual looking plant hardly resembles something that you would steam and eat with your dinner. Although the asparagus family contains thousands of species, many of which are not edible, the Chaparral yucca does in fact have edible parts. Although it is rarely eaten in the present day, several Native American tribes consumed the rosettes, immature pods, flowering stalks, and flowers. The roots are hardly if not ever consumed, but often mistaken for the “yuca”, or cassava root, a completely unrelated plant that serves as a staple in the diet of many tropical nations.

Chaparral Yucca can be found as far North as Monterey and Fresno Counties, south into Mexico, and east into Arizona. It favors habitats on the warmer side, and is one of the most common species in coastal sage scrub and Chaparral. Additionally it can be found in lower densities in deserts, creosote bush scrub, dry woodlands, and yellow pine forest. This hardy plant is highly tolerant of dry, rocky soils, and can even be spotted springing out of some very craggy, inhospitable looking rock formations. The way in which it juts out from the surrounding vegetation creates a striking contrast that can make for some intriguing hiking scenery. A similar species, the Century Plant, is often confused with the Chaparral Yucca. This relative of the Chaparral Yucca does not live nearly as long as its name suggests, rather only a meager 10-30 years. It can be distinguished from the Chaparral Yucca most easily by its height, as it grows to be much taller: up to twenty-six feet high.

Although the Chaparral Yucca can establish itself on very dry soils, its bloom is dependent upon the amount of rainfall received that season. In particularly dry years, no Chaparral Yuccas may flower at all. Most Chaparral Yuccas are “monocarpic”, meaning that they flower for one season and then die. However, there are a handful of subspecies of Chaparral Yucca recognized, and some of these subspecies appear to be “polycarpic”, or flowering many seasons before dying. It takes a Chaparral Yucca at least four years to reach maturity and flower. Flowering occurs most often from April through June, although it may occur as early as February and as late as July. This season, although dryer than average, has provided enough precipitation for a modest display of Chaparral Yucca flowers. For those nature-inclined individuals and outdoor enthusiasts, now is the time to see these impressive plants in the height of their bloom.

Curiously, there has only been one animal reported to pollinate Chaparral Yuccas: the California Yucca Moth (Tegeticula maculata). This tiny moth has a mutualistic relationship with these plants, in which the moth facilitates the reproduction of the plant, and in return the plant provides a source of food for the moth’s young. At nighttime, an adult female Yucca Moth will collect pollen from the flower of one Chaparral Yucca, fly to a flower of another, and lay a handful of eggs in the flower’s ovary. After carefully depositing her eggs, she deposits pollen on the stigma of the same flower in which she laid her eggs, ensuring fertilization. Her eggs will soon hatch and the voracious larvae will now have a plentiful food source to sustain them until pupation: the seeds produced by the pollinated yucca flower. The moth takes care to lay just enough eggs so as to not deplete the plant’s seed supply. In a few short weeks, the larvae will drop to the ground, bury themselves, and form cocoons. They will remain underground in the pupal stage until the following spring, when they will emerge in their fully-grown moth form and start the cycle all over again. In some years with inadequate rainfall and no flowering yuccas, the moths will not emerge from underground and remain dormant until a following season.

Mule Deer (Odocoileus hemionus)

In addition to sustaining the California Yucca Moth, Chaparral Yuccas provide a source of food to various birds and mammals of Southern California. The Dusky-Footed Woodrat, a nocturnal “packrat” known for making large, domed nests out of sticks, twigs, and leaves, often feeds on the fruit of Chaparral Yuccas. Mule deer may feast upon the flowers and flower stalks in some areas. If you are feeling particularly adventurous and have an urge to taste the flowers on this plant, be warned; they are quite bitter. The Native Americans boiled the flowers to remove the bitterness and make them more palatable.

Works Cited:

Agave Americana. Calflora Taxon Report. http://www.calflora.org/cgi- bin/species_query.cgi?where-calrecnum=9006. Accessed 5/14/12.

Gucker, Corey L. 2012. Hesperoyucca whipplei, H. newberyyi. Fire Effects Information System. http://www.fs.fed.us/database/feis/plants/forb/hesspp/all.html

Hesperoyucca whipplei. Calflora Taxon Report. http://www. calflora.org/cgi-bin/species_query.cgi?where-calrecnum=9995. Accessed 5/9/12.

Moisset, Beatriz. 2010. Yucca Moths (Tegeticula Sp.) U.S. Forest Service: Celebrating Wildflowers. http://www.fs.fed.us/wildflowers/pollinators/pollinator-of- the-month/yucca_moths.shtml

Plant Guide: Chaparral Yucca. United States Department of Agriculture Natural Resources Conservation Service and UC Davis Arboretum. http://plants.usda.gov/plantguide/pdf/cs_yuwh.pdf. Accessed 5/9/12

Tirmenstein, D. A. 1989. Yucca Whipplei. All Refer. http://reference.allrefer.com/wildlife-plants- animals/plants/shrub/yucwhi/all.html

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