1 Leaves connate at the base, opposite; flowers solitary in the axils of leaves; flowers 3-4-merous; [subfamily Crassuloideae]

1 Leaves distinct, whorled or alternate; flowers in terminal cymose inflorescences; flowers 4-5 (-8)-merous.

..2 Petals connate as a tube; leaves serrate, bearing plantlets in the serrations; [subfamily Kalanchoideae]

..2 Petals distinct or at most basally connate; leaves entire, crenate, or serrate, but not bearing plantlets along the margin; [subfamily Sempervivoideae].

....3 Plants with spheroidal basal rosettes consisting of dozens or more spirally arranged leaves; flowers 8-16-merous

....3 Plants with or without basal rosettes (if rosettes present, these not as above); flowers 4-6-merous

......4 Flowers (5-) 7 (-9)-merous

......4 Flowers 4-5-merous.

........5 Perennials without rosettes, the stems 0.5-10 dm tall (dying back in winter to the rootstock); leaves large, relatively thin in texture, usually 5-25 times as wide as thick, often crenate; flowers pink, purple, white, or greenish.

..........6 Flowers 5-merous, bisexual; flowering stems 2-10 dm tall, from an underground, tuberous base; average leaves 3-11 cm long, 1-5 cm wide; ovaries attenuate at the base; [tribe Telephieae]

..........6 Flowers 4 -(5)-merous, usually unisexual and then the plants dioecious; flowering stems 0.5-4 dm tall, from axils of brown scale-leaves clothing a stout rootstock at least in part exposed aboveground; average leaves 1-5 cm long, 0.4-1.5 cm wide; ovaries not attenuate at the base; [tribe Umbiliceae]

........5 Perennials or annuals with or without rosettes, the stems < 2 dm tall (the perennials with stems persistent through the winter); leaves smaller, flat or terete, relatively thicker, entire; flowers white or yellow; [tribe Sedeae].

............ 7 Leaves flat; leaf margins toothed or crenate.

............ ..8 Leaves alternate; petals yellow

............ ..8 Leaves opposite; petals white to pink

............ 7 Leaves flat, subterete, or terete; leaf margins entire.

............ ....9 Carpels united basally (to about 1/3 their length); petals cucullate, initially partly enclosing 4 of the 8 stamens; follicles dehiscing by a tear-shaped valve on the lower surface; stem and leaves normally red; [of granitic flatrocks of the Piedmont of GA, NC, SC, and VA, and sandstone glades in TN, nw. GA, and AL]

............ ....9 Carpels free; petals flat, never enclosing any of the 8 anthers; follicle dehiscing by a longitudinal slit along the adaxial (upper) suture; stem and leaves normally green, sometimes somewhat pink or reddish; [collectively of various habitats, including similar habitats as Diamorpha]