1 Flowers doubled, the corona divided into numerous segments resembling tepals; stamens usually petaloid.

  2 Corona segments shorter than the tepal lobes; flowers bicolored, corona segments usually bright orange and tepals pale yellow to creamy-yellow (petaloid stamens cream to yellow in color)

1 Flowers not doubled, the corona undivided (like a drinking glass or cup) and distinct from the tepals; stamens not petaloid.

    3 Tepal lobes 10-15 mm long; corona 3-5 mm long; leaves dark green, either cylindrical and hollow or somewhat flattened and grooved; umbel (or stem) with 3-10 flowers.

      4 Leaves somewhat flattened, grooved, 3-10 mm wide; tepal lobes light lemon-yellow; corona yellow-orange, distinctly darker than the tepal lobes

      4 Leaves cylindrical (terete), 2-4 mm wide; tepal lobes golden-yellow; corona golden-yellow, the same as the tepal lobes or only slightly darker

    3 Tepal lobes 10-50 mm long; corona 5-50 mm long; leaves green to glaucous, flattened, solid; umbel (or stem) with 1-20 flowers.

        5 Tepal lobes distinctly reflexed back, ca. 180 degrees

        5 Tepal lobes borne at close to a 90 degree angle to the flower axis.

          6 Hypanthial tube (below the tepal lobes) parallel-sided (though sometimes suddenly expanded at its apex); corona < 10 mm long, usually wider than high; corona < 0.5× as long as the perianth lobes; corona rarely undulate; umbel (or stem) with 1-10 flowers; stamens of 2 distinct lengths.

             7 Corona rim red, contrasting with the white or yellow corona (though sometimes fading when dried); umbel (or stem) with 1 flower

             7 Corona of a single color, all white or yellow; umbel (or stem) with (1-) 2-8 (-20) flowers.

               8 Umbel (or stem) with (1-) 2 (-3) flowers; pollen grains malformed (sterile)

               8 Umbel (or stem) with (2-) 3-8 (-20) flowers; pollen grains normal, turgid (fertile).

                 9 Corona white; umbel (or stem) with < 20 flowers

                 9 Corona yellow; umbel (or stem) with (2-) 3-8 (-15) flowers

          6 Hypanthial tube (below the tepals) distinctly widening toward its apex; corona usually > 10 mm long, usually as long as wide or longer than wide; corona usually > 0.5× as long as the perianth lobes; corona margin undulate; umbel (or stem) with 1(-3) flowers; stamens of the same length or nearly so.

                   10 Tepal lobes linear to lanceolate, < 5 mm wide

                   10 Tepal lobes ovate, triangular-ovate, or suborbicular, > 10 mm wide.

                     11 Corona 10-25 mm long, nearly as long as or distinctly shorter than the tepal lobes.

                       12 Umbel (or stem) with (1-) 2-4 flowers; corona and tepal lobes the same color; leaves green, < 8 mm wide; stem nearly terete

                       12 Umbel (or stem) with 1 (-3) flowers; corona usually conspicuously darker in color than the tepal lobes; leaves green or glaucous, > 8 mm wide; stem distinctly 2-edged

                          13 Umbel (or stem) with 1 (-3) flowers; corona > 0.75× as long as the tepal lobes; leaves green; flowering stems usually < 30 cm tall

                          13 Umbel (or stem) with 1 flower; corona < 0.75× as long as the tepal lobes; leaves somewhat glaucous; flowering stems often > 30 cm tall