1	"Plant parasite on stem of woody host"	2
1	"Plant free-living and rooted in ground or root-parasite"	3
2	"Flowers of parasite emerging directly from stem of host, parasite otherwise growing within tissues of host; leaves 0; on _Psorothamnus_"	"Apodanthaceae {Pilostyles thurberi}"
2	"Flowers of parasite borne in inflorescences on branches of parasite; leaves scale-like or with expanded blades; on various woody hosts [not _Psorothamnus_]"	Viscaceae
3	"Leaf blade 1--2+ m, covered with prickles --- perianth actually of 2 whorls but petals very small, easily overlooked"	"Gunneraceae {Gunnera tinctoria}"
3	"Leaf blade << 1 m, not prickly"	4
4	"Leaves [at least proximal] whorled, all cauline"	5
4	"Leaves alternate or opposite (or sometimes some or all basal)"	8
5	"Plant terrestrial"	Rubiaceae
5	"Plant +- aquatic"	6
6	"Leaves entire"	"Plantaginaceae {Hippuris}"
6	"Leaves toothed to deeply divided"	7
7	"Leaves repeatedly forked"	"Ceratophyllaceae {Ceratophyllum demersum}"
7	"Leaves [at least submersed] pinnately divided"	"Haloragaceae {Myriophyllum}"
8	"Inflorescence bracts large, petal-like; perianth 0 --- inflorescence a flower-like spike"	"Saururaceae {Anemopsis californica}"
8	"Inflorescence bracts not at all petal-like; perianth present"	9
9	"Perianth parts free or nearly so"	10
9	"Perianth parts fused"	18
10	"Leaves glabrous, round-peltate or -reniform; plant aquatic with stolons or rhizomes floating in shallow water or rooted in wet soil"	"Araliaceae {Hydrocotyle}"
10	"Leaves glabrous or hairy, leaf shape various; plant terrestrial if leaves round-reniform"	11
11	"Inflorescence a simple or compound umbel"	Apiaceae
11	"Inflorescence various or flowers solitary"	12
12	"Plant aquatic, floating, stranded on mud, or rooted in bottom sediments"	13
12	"Plant terrestrial or sometimes growing in damp soil"	14
13	"Sepals, stamens 5; pedicel 1--4(8) mm; leaves alternate (sometimes +- opposite or whorled), blade linear"	"Campanulaceae {Howellia}"
13	"Sepals, stamens 4; pedicel 0--0.5 mm; leaves opposite, blade narrowly elliptic to +- ovate"	"Onagraceae {Ludwigia palustris}"
14	"Leaves all basal"	"Saxifragaceae {Heuchera cylindrica}"
14	"Leaves cauline, at least in part"	15
15	"Fruit an achene; sepals 3--5; leaves alternate, +- entire, petiole +- = blade"	"Chenopodiaceae {Beta}"
15	"Fruit a capsule or +- nut-like [hard, indehiscent, 3--9-seeded with 2--5-horns]; sepals 3--9; leaves alternate or opposite, entire to pinnately lobed, petiole often < blade"	16
16	"Perennial herb; stems erect; leaves generally unequally pinnately lobed; styles long, forked"	"Datiscaceae {Datisca glomerata}"
16	"Annual; stems prostrate to erect; leaves entire or toothed; styles short, not forked"	17
17	"Styles 2--9; leaves +- fleshy, often +- papillate"	Aizoaceae
17	"Style 1; leaves not fleshy, not papillate"	Campanulaceae
18	"Inflorescence of involucred heads or umbels"	19
18	"Inflorescence not of involucred heads or umbels, flowers solitary or variously clustered"	20
19	"Ovary truly inferior; anthers fused around style or, if free, the flowers unisexual; stigma lobes 2"	Asteraceae
19	"Ovary actually superior, but appearing inferior [tightly enclosed by perianth base]; anthers free; stigma unlobed"	Nyctaginaceae
20	"Flowers large, solitary, red to maroon or brown; perianth lobes 3 --- leaves cordate to reniform, long-petioled"	"Aristolochiaceae {Asarum}"
20	"Flowers generally +- small, generally clustered, not red to maroon or brown; perianth lobes (3)4--5(7)"	21
21	"Leaves alternate"	22
21	"Leaves opposite"	23
22	"Tendrils 0; leaves entire; flowers bisexual"	"Comandraceae {Comandra umbellata subsp. californica}"
22	"Tendrils present; leaves palmately lobed; flowers unisexual"	Cucurbitaceae
23	"Flowers bilateral"	Valerianaceae
23	"Flowers +- radial"	24
24	"Perianth lobes 5; ovary actually superior [tightly enwrapped by hardened or winged calyx base]; leaves of a pair equal or unequal"	25
24	"Perianth lobes 3--4; ovary truly inferior; leaves of a pair equal"	26
25	"Calyx green, not at all corolla-like, very inconspicuous; sepals erect, free or nearly so above the level of the ovary, thickened and linear, erect; leaves narrowly linear, needle-like, generally 1--2 cm or shorter, generally those of a pair equal"	"Caryophyllaceae {Scleranthus}"
25	"Calyx corolla-like in color and texture, often very showy; sepals fused well above level of ovary, calyx lobes wide and thin, +- spreading; leaves linear to ovate, often > 2 cm, those of a pair often unequal"	Nyctaginaceae
26	"Stamens 3--4; leaves entire or teeth minute, prickle-like"	Rubiaceae
26	"Stamens 8; leaves with rounded teeth"	"Saxifragaceae {Chrysosplenium}"