1	"Specimens available for examination without flowers, these either not present on the specimen or not produced at all"	2
1	"Specimens available for examination with flowers, often also producing seeds within fruits [ANGIOSPERMS]"	7
2	"Bulblets [small bulbs or corms that are dispersed in place of seeds or fruits] formed in place of flowers in inflorescence or inflorescence-like cluster"	"Family Group 1"
2	"Bulblets 0"	3
3	"Sporangia, sporangium cases, seeds, cones, or cone-like structures 0 or not readily apparent [plants in strictly vegetative condition]"	4
3	"Sporangia, sporangium cases, seeds, cones, or cone-like structures present"	5
4	"Plant aquatic"	"Family Group 2"
4	"Plant terrestrial [Note: terrestrial plants in strictly vegetative condition cannot be identified with this key]"	"Cannot be identified"
5	"Herbs reproducing by spores released directly from sporangia, the sporangia variously located [on abaxial leaf face, in stalked cluster arising from petiole or blade base, in hardened case at petiole base, in axils of linear or scale-like leaves, or in terminal cone-like structure], seeds and pollen never formed [LYCOPHYTES and FERNS]"	"Family Group 3"
5	"Herbs to trees reproducing by seeds"	6
6	"Ovules exposed to air at time of pollination, not enclosed in ovary; pollen grains deposited directly on ovule, stigma 0; seeds, if present, borne between scales of cone or naked on branches, fruit not produced; shrubs or trees [GYMNOSPERMS]"	"Family Group 4"
6	"Ovules enclosed in ovaries that on available specimens have matured as dehiscent or indehiscent fruits; seeds enclosed within ripened pericarp of fruit [if dry remains of flowers are present it may be possible to determine the family of a fruiting specimen under  couplet 7 in this key, but not all fruiting specimens may be identifiable here]"	"Cannot be identified"
7	"Specimens with only cleistogamous flowers — fruits developing without flowers opening"	"Family Group 5"
7	"Specimens with open flowers"	8
8	"Specimens with unisexual flowers of only 1 kind [staminate or pistillate, but not both]; plants dioecious or monoecious"	9
8	"Specimens with bisexual flowers or with both staminate and pistillate flowers [on same or different individuals]; plants bisexual, dioecious, or monoecious (occasionally with mixture of bisexual and unisexual flowers)"	12
9	"Specimen with only staminate flowers"	10
9	"Specimen with only pistillate flowers"	11
10	"Herb or subshrub, woody only at base"	"Family Group 6"
10	"Tree or shrub, conspicuously woody"	"Family Group 7"
11	"Herb or subshrub, woody only at base"	"Family Group 8"
11	"Tree or shrub, conspicuously woody"	"Family Group 9"
12	"Pistils 2 or more per flower [carpels > 1, free to the base]"	"Family Group 10"
12	"Pistil 1 per flower [carpel 1 or carpels > 1 fused at least proximally]"	13
13	"Perianth 0 or in a single whorl [appearing to be either sepals or petals but not both], sometimes reduced to scale-like or bristle-like structures"	14
13	"Perianth in 2 or more whorls (generally both sepals and petals) or perianth parts spiraled 2 or more times around floral axis"	18
14	"Tree or shrub, conspicuously woody"	15
14	"Herb or subshrub, woody proximally if at all"	16
15	"Inflorescence, at least the staminate, a catkin or catkin-like spike; flowers unisexual"	"Family Group 11"
15	"Inflorescence various but not catkin-like; flowers bisexual or unisexual"	"Family Group 12"
16	"Leaf venation parallel or leaves and stem not differentiated"	"Family Group 13"
16	"Leaf venation generally pinnate or palmate (sometimes only midvein evident) or leaves reduced to bladeless scales"	17
17	"Ovary inferior"	"Family Group 14"
17	"Ovary superior"	"Family Group 15"
18	"Perianth parts 2 or 3 per whorl"	"Family Group 16"
18	"Perianth parts generally 4 or 5 per whorl (rarely some other number or whorls differing in number of parts) or in a spiral with the number of parts indefinite"	19
19	"Petals fused into a ring or a tube, the corolla generally falling as a unit [corolla of free petals fused to a hypanthium should be keyed under 19']"	20
19	"Petals free, at least at base, attached and generally falling singly (sometimes individually joined to a hypanthium; in a few families ± joined and falling in groups, but not forming a ring or a tube, or petal 1)"	22
20	"Ovary inferior or partly so"	"Family Group 17"
20	"Ovary superior"	21
21	"Corolla bilateral"	"Family Group 18"
21	"Corolla radial"	"Family Group 19"
22	"Leaf compound or so deeply divided as to appear compound"	"Family Group 20"
22	"Leaf simple, sometimes much reduced"	23
23	"Ovary inferior or partly so"	"Family Group 21"
23	"Ovary superior"	24
24	"Stamens > 2 × as many as petals"	"Family Group 22"
24	"Stamens <= 2 &times; as many as petals"	25
25	"Tree or shrub, conspicuously woody"	"Family Group 23"
25	"Herb or subshrub, woody only at base"	"Family Group 24"