Agave americana |
Agave univittata |
|||||
---|---|---|---|---|---|---|
American agave, American century plant, centuryplant, maguey americano |
Mckelvey's century plant, thorn-crested agave |
|||||
Habit | Plants acaulescent or short-stemmed, commonly suckering, trunks less than 2 m; rosettes not cespitose, 10–20 × 20–37 dm. | Plants acaulescent, usually suckering; rosettes densely cespitose, 3–6 × 5–10 dm. | ||||
Leaves | erect, spreading to ascending, occasionally reflexed, 80–200 × 15–25 cm; blade light green to green or glaucous-gray, sometimes variegated or cross-zoned, narrowly to broadly lanceolate, smooth, rigid; margins nearly straight or undulate to crenate, armed, teeth single, 5–10 mm, 1–4 cm apart; apical spine dark brown to grayish, conical or subulate, 2–6 cm. |
mostly erect, 30–40(–70) × 3–4.5(–5) cm; blade light green to yellowish green, without bud-prints, linear-lanceolate, stiff, adaxially plane to concave toward apex, abaxially convex toward base; margins undulate to crenate, nonfiliferous, not easily detached, conspicuously armed, teeth single or occasionally double, 4–6(–8) mm, 1–2 cm apart; apical spine reddish to grayish, subulate, 1–1.5(–2) cm. |
||||
Scape | 5–9 m. |
3–4.5(–5) m. |
||||
Inflorescences | paniculate, not bulbiferous; bracts persistent, triangular, 5–15 cm; lateral branches 15–35, horizontal to slightly ascending, comprising distal 1/3–1/2 of inflorescence, longer than 10 cm. |
spicate, densely flowered on distal 1/2; bracts caducous, acicular, 3–5 cm; peduncle 4 cm or shorter. |
||||
Flowers | erect, 7–10.5 cm; perianth yellow, tube funnelform to cylindric, 8–20 × 12–20 mm, limb lobes erect, subequal, 20–35 mm; stamens long-exserted; filaments inserted above mid perianth tube, erect, yellow, 6–9 cm; anthers yellow, 25–35 mm; ovary 3–4.5 cm, neck constricted, 3–6(–8) mm. |
1 on short pedicel, or 2–7 per cluster, erect, 3.5–4(–4.5) cm; perianth greenish white to yellowish green, tube campanulate, 2–4 × 8–10 mm, limb lobes erect to slightly spreading, subequal, 14–20 mm; stamens long-exserted; filaments inserted on rim of perianth tube, spreading, greenish or lavender, 3–4.5 cm; anthers pale yellow, 15–20 mm; ovary 1.8–2.2 cm, neck constricted 5–7 mm. |
||||
Capsules | short-pedicellate, oblong, 3.5–8 cm, apex beaked. |
sessile or short-pedicellate, oblong and 1.8–2.5 cm or globose and 1.5–2 cm, apex beaked. |
||||
Seeds | 6–8 mm. |
5–6 mm. |
||||
2n | = 60. |
|||||
Agave americana |
Agave univittata |
|||||
Phenology | Flowering spring. | |||||
Habitat | Sandy flats | |||||
Elevation | 0–100 m (0–300 ft) | |||||
Distribution |
sw United States; Mexico
|
TX; Mexico |
||||
Discussion | Subspecies 2 (2 in the flora). Various chromosome numbers have been reported for Agave americana under a variety of names, typically without regard to the plant’s origin or its precise taxonomic disposition. Nonetheless, the species is most certainly a polyploid complex based on x = 30, with reports of n = 30 and 2n = 60, 120, and 180 documented by S. D. McKelvey and K. Sax (1933), H. Matsuura and T. Sutô (1935), E. B. Granick (1944), A. K. Sharma and U. C. Bhattacharyya (1962), M. S. Cave (1964), S. Banerjee and A. K. Sharma (1987), Huang S. F. et al. (1989) and B. Vijayavalli and P. M. Mathew (1990). Various dysploids have also been reported (A. F. Dyer et al. 1970; J. L. Strother and G. L. Nesom 1997). See H. S. Gentry (1982) for details. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
The name Agave lophantha was mentioned by C. J. W. Schiede (Linnaea 4: 582. 1829) without a description. C. S. Kunth (Enum. Pl. 5: 838. 1850) validated the name, but not before A. univittata was proposed. Neither name is typified nor is any authentic material known. H. S. Gentry (1982) incorrectly retained A. lophantha and it is now widely used. A. J. Breitung (1959) was the first to adopt A. univittata, and that name is taken up here. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
||||
Key |
|
|||||
Source | FNA vol. 26, p. 452. | FNA vol. 26, p. 449. | ||||
Parent taxa | Agavaceae > Agave | Agavaceae > Agave | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | A. heteracantha, A. lophantha | |||||
Name authority | Linnaeus: Sp. Pl. 1: 323. (1753) | Haworth: Philos. Mag. Ann. Chem. 10: 415. (1831) | ||||
Web links |