Plants usually perennial, occasionally epiphytic, sometimes monocarpic or polycarpic, monoecious, dioecious, or polygamodioecious, small to gigantic, sometimes arborescent, usually scapose. Stems subterranean or aboveground, sometimes branched. Leaves simple, annual or long-lived, in terminal rosettes or occasionally cauline, sessile or occasionally pseudo-petiolate; blade linear, lanceolate, oblanceolate, ovate, or elliptic, fibrous, thin and flexible, thick and rigid or succulent, or fibrous, often glaucous, margins entire, serrulate, dentate, denticulate, corneous, or filiferous, apex rigid or flexible, sometimes pungent, often with short or long spine. Inflorescences terminal or axillary spikes, racemose or paniculate, sometimes umbellate, bracteate, often huge; bracts ascending or erect, occasionally reflexed, leaflike proximally, scalelike distally. Flowers 6-merous, bisexual or functionally unisexual; perianth of 2 similar petallike whorls, semisucculent; tepals distinct or connate into tube, apex glandular or glandular-pubescent; stamens included or exserted; filaments often broadened and succulent, glabrous, pubescent, or papillose; anthers versatile, dehiscence longitudinal; ovary superior or inferior, 3-locular or occasionally 1-locular, 3-angled, ovoid, or cylindrical, with axillary or rarely parietal placentation; style included or exserted; stigmas 1 or 3, 3-lobed or capitate; pedicel usually distinct, articulate or not, rarely absent. Fruits occasionally baccate, usually capsular and sometimes winged or lobed, or indehiscent and dry or fleshy. Seeds 1-3(-many) per locule, flattened, 3-angled, hemispheric, ovoid, obovoid, or globose.
There is little agreement on the treatment of Agavaceae. The group containing Agave, Yucca, Furcraea, Hesperaloe, and Manfreda generally has been accepted as the core of Agavaceae, or as subfamilies Agavoideae and Yuccoideae, but treatment of Dracaena, Sansevieria, Cordyline, Nolina, and Dasylirion has been varied. A. L. Takhtajan (1987) and R. F. Thorne (1992b) placed these genera in Dracaenaceae but treated them at different levels. Takhtajan located them in the subfamily Dracaenoideae within sections Nolineae (Nolina and Dasylirion), Sansevierieae (Sansevieria), and Dracaeneae (Cordyline and Dracaena). Thorne, on the other hand, placed these same groupings at the subfamily level. R. M. T. Dahlgren et al. (1985) recognized them as separate families, Nolinaceae (Nolina and Dasylirion), Dracaenaceae (Sansevieria and Dracaena), and Asteliaceae (Cordyline), in addition to the Agavaceae (Yucca, Hesperaloe, Agave, Manfreda, and Furcraea).
A. Cronquist (1981) based his broadly circumscribed Agavaceae on a common xerophytic habit. However, the karyotype of 5 long and 25 short chromosomes for the Agavoideae and Yuccoideae is distinct from the karyotypes of the other subfamilies that Cronquist included in the Agavaceae. Current research on the phylogenetics of moncotyledons, using DNA sequences of rbcL, support the separation of Dracaena, Nolina, and Dasylirion from Agavaceae (M. R. Duvall et al. 1993b). We believe that a broad interpretation of the Agavaceae unites groups that should be recognized as separate.
Many genera in Agavaceae are economically important. All genera in the Agavoideae and Yuccoideae contain steroidal sapogenins; some have been used in folk medicine, and locally and commercially as soap (G. Blunden et al. 1978; S. E. Verhoek 1978; M. Wall et al. 1957). They provide fibers for cordage, baskets, and hats, as well as food and drink for many indigenous peoples of the southwestern United States (H. S. Gentry 1982). They are also used as commercial fiber and beverage crops in Latin America and the Old World (H. Brucher 1989). In the southern United States, some species in each genus are cultivated and represented in the flora, and at least one species of Yucca is now grown as far north as Canada. Collectors should record the uses of these plants in their notes along with the critical information on plant habit and morphology. Photographs are often important tools for the identification of these plants, and, with the advent of digital cameras, are now much easier to obtain and process.
PLANT: Trees, shrubs, or perennial herbs, monocarpic (flowering once and then dying) or polycarpic (flowering more than once). LEAVES: alternate, simple, sessile, tending to be crowded in dense rosettes at end of a caudex or at ends of branches, the margins entire or toothed or filiferous. INFLORESCENCE: axillary or terminal, open, racemose, paniculate or spicate. FLOWERS: usually perfect, actinomorphic to slightly zygomorphic; tepals 6 in 2 whorls, petaloid, often thick and fleshy, distinct or fused below into a floral tube; stamens 6, distinct, adnate to tepal bases or floral tube, the anthers usually dorsifixed, introrse; pistil 3-carpeled, 3-loculed; ovary superior or inferior, usually with basal nectaries; style 1, usually terminal; stigma capitate, 3-lobed; ovules axile, 1-many per locule. FRUITS: loculicidal or septicidal capsules or indehiscent, dry and spongy or baccate. SEEDS: flattened, with endosperm. x = 30 (characteristic size pattern of 5 large and 25 small to medium). NOTES: 8 genera, ca 360 spp., chiefly subtropical, semi-arid and arid regions. Agavaceae are of considerable economic importance, providing cordage, food, alcoholic beverages, detergents, insect repellants, perfumes, and ornamentals. REFERENCES: Hodgson, Wendy. 1999. Agavaceae. Ariz. - Nev. Acad. Sci. 32(1).
Asparagaceae s.l. (sensu lato) is a broadly distinguished family that includes the former families of Asparagaceae, Agavaceae, Hycinthaceae, and Ruscaceae. There is a difficulty in distinguishing many synapomorphies for the clade, with only some seed characters holding them together morphologically. The phylogenetic studies justify the entire clade as this larger circumscription, but it is difficult to distinguish among the subfamilies because of the lack of morphological characters. Pay attention to some of the regional representatives of Agavoideae, and Nolinoideae and what characters hold them together (i.e. basal rosettes, generally fleshy, 6 tepals and stamens).
Mostly shrubs or large rosettes with alternate or all basal leaves fibrous to succulent, alternate or spiral in rosettes or along stem, simple, sheathing. Stem usually a caudex, bulb, or arborescent, often with anomalous secondary growth. Inflorescences racemes, spikes or panicles, 3 sepals, often petaloid (6 tepals), 3 distinct or connate petals, Indeterminate to determinate inflorescence, terminal or axillary, often massive, many monocarpic, some with pups (Agave spp.). Perianth a fused hypanthium, bisexual or perfect, radial to bilateral and usually small, tepals 6, distinct to connate, petaloid, stamens 6, can be epipetalous. Gyonecium of 3 connate carpels, superior to inferior ovary with 3 locules and 1-many ovules per locule, axile placentation and septal nectaries. Fruit a loculicidal capsule to berry, some with phytomelan, some without.
This project was made possible in part by the Institute of Museum and Library Services [MG-70-19-0057-19].