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Key to Agavaceae

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1 Plants with erect stems; leaves cauline.
  2 Plant an herb, the arching stems producing a whorl of leaves at the tip, which can root down and form a new plant
  2 Plant woody, a shrub or small tree.
    3 Ovary inferior; leaves to 25 cm wide, the margin with stout spinose teeth or entire
    3 Ovary superior; leaves to 6 cm wide, the margin fibrous, entire (cartilaginous), or serrulate
1 Plants acaulescent; leaves in basal rosettes or crowded very low on a short stem.
      4 Margins of leaves fraying into coarse, white or grayish curly fibers or with small serrulate yellowish, orangish, or reddish edges, leaves evergreen; tepals to about 4 cm long.
        5 Flowers narrowly tubular or broadly campanulate, rosy red or salmon-colored (rarely yellow); capsules ovoid; leaves conspicuously involute
        5 Flowers globose or campanulate, white to greenish or yellowish; capsules mostly oblong, rarely ovoid; leaves not or slightly involute
      4 Margins of leaves entire, not fraying or with stout spinose teeth, leaves herbaceous or evergreen (in Agave and Furcraea); tepals < 2 cm long.
          6 Leaves oblong-acute, 2-25 cm wide, 2-20× as long as wide, fleshy or leathery.
             7 Tepals separate, not forming a tube; filaments dilated near their bases; [FL peninsula]
             7 Tepals fused below, forming a tubular perianth; filaments linear, not dilated; [widespread]
               8 Leaves 3-25 cm wide; inflorescence a panicle (or a spike in A. lophantha); leaf tip spinose and often with stout marginal spines; scale 25-130 dm tall; [exotics planted and rarely persistent or spreading usually on barrier islands, or natives of s. peninsular FL or s. TX].
               8 Leaves 0.6-6 (-9.3) cm wide; inflorescence a spike or raceme; leaf tip soft; leaf margins entire, papillose, or weakly toothed; scape 2-22 dm tall; [collectively widespread in dry habitats in our region]
          6 Leaves linear, 0.3-2.5 cm wide, 20-100× as long as wide, herbaceous or wiry.
                 9 Perianth yellow to yellow-orange, (7.5-) 9-20 mm long; plants from corms; [rare in c. and s. TX]
                 9 Perianth white, greenish white, light blue, blue-violet, or yellow, but if yellow only 4.5-7 mm long; plants from bulbs.
                   10 Leaves with an expanded ovate blade; perianth segments 40-130 mm long; [cultivated plants occasionally escaping]
                   10 Leaves linear; perianth segments 5-18 mm long; [native species].
                     11 Perianth segments 13-18 mm long, blue or nearly white
                     11 Perianth segments 5-7 mm long, white, cream, or yellow