keys to the vascular plants of east texas - Botanical Research ...

408 AGAVACEAE/HESPERALOE
them as a separate family. A number of species of Agavaceae (e.g., Agave and Yucca species)
have been used as a source of food and drink both by native peoples and commercially (e.g., tequila
production). Species of Agave, Hesperaloe, and Yucca are used as ornamentals. Agave,
Furcraea, and Yucca are sources of fiber for cordage and other purposes, and steroidal sapogenins
from Agave and Yucca have been used as soap, in folk medicine, and in making oral contraceptives
(Gentry 1982; Judd et al. 1999; Verhoek & Hess 2002). Family name from Agave,
AGAVE, MAGUEY, or CENTURY-PLANT, a genus of ca. 200 species (Reveal & Hodgson 2002) native
from the s United States to tropical South America. Agave species are the source of fiber (sisal
hemp and henequen), pulque (a Mexican “beer”), and the distilled liquors mescal and tequila.
Based on archaeological records, it is known that Agave species have been used for food and fiber
for at least 9,000 years (Callen 1965; Gentry 1982; Irish & Irish 2000). The common name,
CENTURY PLANT, results from the monocarpic (= flowering only once and then dying) habit of
some species. Such a plant may grow vegetatively for many years or even decades (but probably
not a century) before putting all its energy into a massive burst of flowering—the parent plant
then dies as its seeds mature (Burrows & Tyrl 2001). Agave americana L., (of America), the CEN-
TURY-PLANT or AMERICAN CENTURY-PLANT, native to the sw U.S. and Mexico, is cultivated in East
TX and can long persist (but apparently does not escape); it has large glaucous-gray leaves with
a long (2.5–5 cm) terminal spine and a paniculate inflorescence 5–7 m tall. (Greek: agave, noble
or admirable, in reference to the handsome appearance when in flower) (subclass Liliidae—
Cronquist; order Asparagales—APG II)
FAMILY RECOGNITION IN THE FIELD: usually xerophytic, typically robust perennials, often with
leaves basal or crowded near base of stem (or at stem apex in large tree-like yuccas) and sometimes
sharp-pointed; inflorescence a raceme or panicle; fruit a capsule or fleshy and berry-like.
REFERENCES: Dahlgren et al. 1985; Eguiarte et al. 1994, 2000; Bogler & Simpson 1995, 1996; Eguiarte
1995; García-Mendoza & Galván 1995; Sandoval 1995; Irish & Irish 2000; Verhoek & Hess 2002.
1. Flowers rosy red or salmon-colored (yellow-flowered forms known in cultivation); leaves conspicuously
involute (= with margins rolled inward or toward the upper surface) upon drying,
with the marginsnearly touching ____________________________________________________ Hesperaloe
1. Flowers white to greenish or yellowish (can be reddish brown toward tips); leaves not involute
(can be v-shaped in Manfreda).
2. Ovary inferior; leaves 10–39 cm long, without a hard spiny tip, succulent or semisucculent _____ Manfreda
2. Ovary superior; leaves usually 40 cm long or more OR if shorter, then with a hard spiny tip, not
succulent (but can be thick).
3. Flowers 13–70 mm long or broad; leaves 8–80 mm wide; capsules large (much � 1 cm
long), the seeds numerous in each cell _______________________________________________ Yucca
3. Flowers small, 2.5–7 mm long or broad; leaves 2–12 mm wide; capsules small (� 1 cm
long), the seeds solitary in each cell _________________________ Nolina & Dasylirion (see Nolinaceae)
HESPERALOE Engelm. FALSE YUCCA
Xerophytic, � scapose, rhizomatous perennials; leaves numerous, crowded at base of plant, linear,
to 1.3 m long, succulent, conspicuously involute upon drying; flowering stem usually fewbranched;
pedicels to 35 mm long; flowers tubular to oblong-campanulate, rosy red or salmoncolored
(yellow-flowered forms are known in cultivation); stamens shorter than the tepals; style
varying from much shorter than tepals to slightly exserted; ovary superior; capsules to 3 cm or
more long; seeds black.
AA genus of 5–7 species native to sw North America from c TX to n Mexico (Starr 1997;
Verhoek 1998; Robbins 2002; Turner & Turner 2002). It is most closely related to Hesperoyucca
(AZ, CA, and nw Mexico) and Yucca, the other members of the family with superior ovaries. The
following treatment is based heavily on Turner and Turner (2002). Some are widely cultivated