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Key to Yucca

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1 Plants caulescent when fully developed (an erect shrub or small tree), the lower parts of the stem readily visible because no longer clothed with leaves.
  2 Leaf margins regularly fraying from the leaf as stiff threads; leaves 3-5 cm wide; fruits pendent berries with soft flesh, 7-14 cm long; [e. TX westwards]
  2 Leaf margins not fraying from the leaf as stiff threads; leaves 2.5-8 cm wide; fruits pendent or erect berries with leathery or soft flesh, 2.5-11.5 cm long; [collectively widespread, from se. VA south to s. FL, west to s. AZ].
    3 Fruits with soft flesh, 5-11.5 cm long; leaves very stiff; leaf surface dull; leaves persistent only on upper trunk; [c. TX westwards]
    3 Fruits with leathery or soft flesh, 2.5-8 cm long; leaf surface waxy, shiny; leaves persistent all along frunk; [e. TX eastwards].
      4 Leaf margins minutely notched-serrulate, particularly toward the base; seeds 2.5 mm thick, marginless
      4 Leaf margins entire, smooth, hyaline-brown or hyaline-yellow; seeds ca. 1 mm thick, margined.
        5 Leaf blades rigid, straight; fruits pendent, 5.5-8 cm long; [of NC south to FL]
        5 Leaf blades recurved, flexible; fruits generally erect, 2.5-4.5 cm long; [of GA westward]
1 Plants acaulescent (with a cluster of basal leaves) or with a short stem < 3 dm tall above ground level and clothed with numerous leaves (no part of the aerial stem nonleafy and obviously visible).
          6 Leaf margins fraying from the leaf as stiff threads.
             7 Inflorescence branches glabrous; tepals 5-7 cm long; leaves 2-6 cm wide, stiff, the apex acute-acuminate to obtuse, often concave upward at the apex, the marginal fibrils usually elongate (to 20 cm long)
             7 Inflorescence branches scurfy-pubescent; tepals 3-5 cm long; leaves 1.5-4 cm wide, pliable, the apex attenuate-acuminate, not notably concave, the marginal fibrils usually short (to 4 cm long).
               8 Leaves 1.5-4 cm wide, abundantly thread-margined; [widespread]
               8 Leaves 1-3 cm wide, sparingly thread-margined; [mainly west of the Mississippi River, rarely in the Florida parishes of e. LA]
          6 Leaf margins not fraying from the leaf as stiff threads, minutely notched-serrulate or entire, and hyaline.
                 9 Mature leaves undulate-margined, twisted longitudinally; upper leaf surface strongly concave near its midpoint; [c. TX]
                 9 Mature leaves straight-margined, not twisted; upper leaf surface flat or slightly concave near its midpoint (becoming more concave near the tip); [c. and e. TX].
                   10 Plants solitary; leaves (3-) 3.5-6.5 cm wide; mature leaves blue-green and glaucous; inflorescence axes pubescent; inflorescence branches recurved or drooping; [e. TX]
                   10 Plants solitary or forming of up to 30 rosettes via branching subterranean caudices; leaves 1-3.2 (-4.5) cm wide; mature leaves green; inflorescence axes glabrous or pubescent; inflorescence branches spreading or ascending; [c. and nc. TX]
                     11 Plants solitary or forming colonies of 2-10 rosettes; leaves 1-2.5+ cm wide; mature leaves green, with margins reddish-brown; [coastal se. TX]
                     11 Plants forming colonies of 10-30 rosettes; leaves (1-) 2.5-3.2 (-4.5) cm wide; mature leaves olive or yellowish-green, the margins yellowish; [c. and nc. TX]
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