Yucca, Adam's needle, bear grass, spanish bayonet.
Yucca filamentosa, commonly called yucca, is native to southeastern North America, ranging from Florida to North Carolina and as far over as the Texas (Christman, 2003; Hanelt, 2001). Yucca grows natively in dry soils and sand dunes in coastal regions. It is drought tolerant and thrives in sandy or rocky habitats (Christman, 2003; Hanelt , 2001). Today this species is planted as an ornamental, and horticultural varieties exist. Additionally, many areas Y. filamontosa has become naturalized (Christman, 2003; Hanelt , 2001). Naturalization might have begun prior to the arrival of Europeans, as Native Americans grew this plant near settlements for fiber and soap (Jensen, 2005).
The leaves of Yucca filimentosa are long, narrow, and strap-like. This species has a greatly reduced stalk, so much so, that the plant forms a rosette, appearing to arise from one point. Leaves are spine tipped with numerous long, curly, fibrous threads peeling back along the margins (See photo). Fibers of this species can be used to make rope, rough textiles, and paint brushes (Hanelt , 2001; Jensen, 2005). The thickened root, a rhizome, can be beaten into a lathery pulp which can be used for soap and shampoo (Jensen, 2005).
Showy bell-shaped flowers hang in loose clusters from a central stalk (See photo). This stalk can grow as tall as 3.7 m (12 ft). Flowers have six white tepals and male and female reproductive organs (Hess & Robbins, 2005; OBS, 1999), but cross pollination is required for fruit production. If flowers are pollinated, seed-filled capsules develop. The yucca dies after flowering and fruiting, but produces offshoots that develop into new plants at the base of the plant (Christman, 2003).
Yuccas only known pollinator is the yucca moth. The female yucca moth has specialized mouthparts for collecting pollen. She lays her eggs in an ovary of the yucca flower and then packs the hole with a ball of pollen. This pollen fertilizes the ovary and seeds begin to develop. The moth's larvae require these nutritional seeds for growth and development. This relationship is a mutualism, both species benefit from the exchange. This plant does regulates percentage of seeds eaten by the moth. If seed consumption is high, yucca will selectively drop severely affected fruit, ending seed and larval development. In this highly specialized system, each species has evolved adapting to the other, back and forth in a see-saw fashion. (Riley, 1892; Ramsay & Schrock, 1995;) Each species relies on the other for successful maturation of offspring.
There is some confusion in the number of yucca species; some botanists lump species together as one species; others separate species (Christman, 2003). If speciation occurs following separation of reproductive pools, distinctions, which some botanists consider species delineations, may truly reflect evolution at the population level. Scientists who investigate genetic diversity in Yucca filamentosa and its pollinator are now using genes to answer questions concerning reproductive isolation and evolution among populations (Leebens-Mack & Pellmyr, 2004; Massey & Hamerick, 1998).
Author: Heather Fara, University of Florida. Edited by Olle Pellmyr, University of Idaho
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Map: Red area indicates the native range of Y. filimentosa. There is a much wider population range, if naturalized regions are included. Map created by Heather Fara, University of Florida.
Photos: (a) Flowers by Will Cook, Duke University. (b) Fiberous leaves detail by Linda Lee, University of South Carolina Herbarium. (c) Fruits byJohn Seiler, Virginia Tech. (d) Seed detail bySteve Hurst, USDA-NRCS PLANTS Database. (e) Whole plant by Steve Baskauf, Vanderbilt University.
Christman (2003) Yucca filamentosa.
Nov 10, 2005. www.floridata.com
Cook (2005) Trees, Shrubs, and Woody Vines of North Carolina. Nov 5, 2005. www.duke.edu/~cwcook/trees/yufi.html
Hanelt (2001) Mansfeld's Encyclopedia of Agricultural and Horticultural Crops. Nov 10, 2005. mansfeld.ipk-gatersleben.de/Mansfeld/Taxonomy
Hess & Robbins (2005) Flora of North America Vol. 26, Yucca filmentosa. Nov 10, 2005. www.efloras.org.
Jensen (2005) Yucca filamentosa. Nov 5, 2005. www.bennyskaktus.dk
Kartesz (2006) PLANTS Database: Adam's needle. National Plant Data Center, Baton Rouge. plants.usda.gov
Leebens-Mack & Pellmyr (2004) Patterns of genetic structure among populations of an oligophagous pollinating yucca moth (Tegeticula yuccasella). Journal of Herdity. 95(2):127-35
Massey & Hamerick (1998) Genetic Diversity and Population Structure of Yucca filamentosa (Agavaceae) American Journal of Botany, 85(3):340-345.
OBS (1999) Oklahoma Biological Survey: Yucca filamentosa. Nov 5, 2005. www.biosurvey.ou.edu/shrub/yufi.htm
Ramsay & Schrock (1995) The yucca plant and the yucca moth. The Kansas School Naturalist, 41(2).
Riley (1892) The Yucca Moth and Yucca Pollination
Missouri Botanical Garden Annual Report. 1892(1892):99-158.
Seiler (2005) Virginia Tech Forestry Department: Yucca filmentosa. Version: 5 Nov 2005. www.cnr.vt.edu/dendro/wwwmain.html