Key 2

1	Plants parasitic, leafless, with haustoria; flowers 2-9 mm, in dense clusters or short racemes; corolla inside usually with 5 fimbriate scales opposite sepals		20 Cuscuta
+	Plants not parasitic, with well-developed leaves; inflorescences and corolla not as above (scales present in Lepistemon but entire, ± fused to filaments, flowers 10-22 mm (less than 8 mm in Poranopsis), in ± umbellate cymes).		(2)
2 (1)	Styles 2, free or joined partway.		(3)
+	Style 1 or absent.		(5)
3 (2)	Robust lianas; 1 bract greatly enlarged in fruit, winglike, decurrent along peduncle so fruit is inserted at center		3 Neuropeltis
+	Creeping herbs; bracts always inconspicuous.		(4)
4 (3)	Ovary and fruit deeply 2-lobed; styles gynobasic, joined at base, unbranched		1 Dichondra
+	Ovary entire, not 2-lobed; styles terminal, free, each 2-branched		2 Evolvulus
5 (2)	Style absent; stigma ± conical, 5-10-ridged; fruit a slightly fleshy berry, much longer than inconspicuous sepals		4 Erycibe
+	Style present, longer than stigma (usually much longer); stigma 2-lobed; fruit dry or if ± fleshy then sepals conspicuous, often brightly colored.		(6)
6 (5)	Specimen in flower (fruit needed at couplets 15, 18).		(7)
+	Specimen in fruit (flowers needed at couplets 25, 32-36).		(21)
7 (6)	Stigmas 2, clearly longer than wide, ovate-oblong, elliptic, oblong, clavate, cylindric, to linear.		(8)
+	Stigma 1, ca. as thick as wide, ± capitate or shallowly 2-globose (ellipsoid in Dinetus).		(11)
8 (7)	Bracts or bracteoles prominent, sepal-like or leaflike, persistent in fruit.		(9)
+	Bracts and bracteoles inconspicuous, scalelike, linear or subulate, often deciduous.		(10)
9 (8)	Corolla pale yellow or whitish, center purple; bracts oblong-lanceolate, attached visibly below calyx; capsule pilose		8 Hewittia
+	Corolla pinkish, lavender, or white, center often paler; bracteoles broadly ovate, sometimes saccate, closely enclosing calyx; capsule glabrous		10 Calystegia
10 (8)	Stigmas linear, cylindric, or clavate; hairs 2-armed or simple, always present; pollen ellipsoid, 3-colpate		11 Convolvulus
+	Stigmas elliptic or oblong; hairs stellate (3- or more rayed), sometimes absent; pollen globose, usually 5-zonocolpate		9 Jacquemontia
11 (7)	Ovary 1-locular; flowers in bracteate racemes or panicles, lower bracts often cordate.		(12)
+	Ovary 2(-4)-locular; flowers in relatively few-branched cymes, umbel-like or capitulate; bracts not cordate (except some Argyreia), often minute and/or soon falling.		(14)
12 (11)	Herbaceous twiners; corolla glabrous outside or lobes with a minute apical tuft of hairs		7 Dinetus
+	Woody climbers; corolla pubescent outside on midpetaline bands.		(13)
13 (12)	Flowers less than 8 mm, white, in ± crowded panicles; sepals ± equal; bracteoles minute, scalelike		5 Poranopsis
+	Flowers 10-35(-50) mm, blue, violet, or white, in racemes or few-branched panicles; sepals unequal; bracteoles sepal-like, forming a secondary calyx (calycle) immediately below calyx		6 Tridynamia
14 (11)	Corolla urceolate; filaments dilated basally into a concave scale, scales arched over ovary		16 Lepistemon
+	Corolla campanulate, funnelform, or salverform; filaments basally pubescent or glandular, not forming scales.		(15)
15 (14)	Leaves (and often sepals and corolla lobes) with small dark glandular dots; fruiting sepals leathery, apex rounded		19 Stictocardia
+	Leaves (sepals, corolla lobes) without glandular dots; fruiting sepals not leathery, apex often acute.		(16)
16 (15)	Flowers solitary, nodding; corolla waxy, limb erect, subentire or shallowly 5-dentate; slender ± woody twiners (in China)		17 Blinkworthia
+	Flowers few to many in cymes or capitula; corolla mostly membranous or transparent, limb spreading or recurved, subentire, 5-lobed to deeply 5-parted; twining or trailing herbs, scandent shrubs, or lianas.		(17)
17 (16)	Pollen spiny.		(18)
+	Pollen smooth.		(19)
18 (17)	Fruit a fleshy, mealy, or leathery berry, indehiscent or breaking up irregularly; adaxially sepals and berry often brightly colored		18 Argyreia
+	Fruit a capsule, usually 4- (or 6)-valved, woody and seemingly indehiscent in I.aquatica; adaxially sepals and fruit green or brown		15 Ipomoea
19 (17)	Inner 3 sepals tapering into slender points apically; leaves linear, oblong-linear, lanceolate-elliptic, or oblanceolate to spatulate, base hastate, ± clasping stem; pollen pantoporate; herbaceous, stems prostrate or tips twining		13 Xenostegia
+	Inner sepals not tapering into slender points apically; leaves variously shaped, usually wider, bases rarely clasping (except some M. hirta); pollen colpate or rugate; woody or herbaceous, often climbing, sometimes prostrate.		(20)
20 (19)	Stems terete or striate, not winged; corolla much longer than calyx, usually yellow, less often lilac, pink, reddish, white, or white with red center		12 Merremia
+	Stems (and often petioles, peduncles) winged; corolla ca. 2 as long as calyx, white with yellow center		14 Operculina
21 (6)	Stems (and often petioles, peduncles) winged; fruit with a thickened circumscissile lid that separates from ± papery and tardily shattering endocarp		14 Operculina
+	Stems terete or striate, not winged; fruit dehiscent or indehiscent but without a thickened circumscissile lid.		(22)
22 (21)	Fruit indehiscent.		(23)
+	Fruit a 4- or more-valved capsule.		(29)
23 (22)	Stems prostrate, fistulose, growing in water or in very wet situations		15 Ipomoea
+	Stems climbing or prostrate, not fistulose, growing on land.		(24)
24 (23)	Calyx enlarged, < length of fruit; adaxial surface of sepals often brightly colored (except Blinkworthia, some Argyreia); fruit fleshy, mealy, or leathery		18 Argyreia
+	Calyx greatly enlarged, clearly longer than fruit; adaxial surface of sepals greenish or brownish; fruit papery to thinly woody.		(26)
25	Flowers solitary, nodding; corolla waxy, limb erect, subentire or shallowly 5-dentate; fruiting sepals ± enclosing berry, adaxially brownish		17 Blinkworthia
+	Flowers few to many in cymes or capitula; corolla membranous or transparent, limb spreading to recurved, subentire, 5-lobed, to deeply 5-parted; fruiting sepals usually reflexed from berry, adaxially often colored		18 Argyreia
26 (24)	Leaves (and often sepals and corolla lobes) with minute blackish glandular dots abaxially; fruit with 4 or less seeds, wall at length eroding between septa, lantern-shaped		19 Stictocardia
+	Leaves (and sepals and corolla lobes) without blackish dots; fruit 1-seeded, wall not eroding and becoming lantern-shaped.		(27)
27 (26)	Herbaceous twiners; all 5 sepals ± equally elongated in fruit or inner sepals slightly less so		7 Dinetus
+	Woody climbers; outer 2 or 3 sepals greatly elongated in fruit, inner sepals much less so.		(28)
28 (27)	Bracteoles minute, scalelike; fruiting sepals with a single midvein and reticulate secondary veins		5 Poranopsis
+	Bracteoles sepal-like, forming a secondary calyx (calycle) immediately below calyx; fruiting sepals with 7, 9, or 11 parallel longitudinal veins		6 Tridynamia
29 (22)	Bracts or bracteoles enlarged, surrounding capsule and sepals.		(30)
+	Bracts and bracteoles not enlarged, not surrounding calyx and capsule, sometimes deciduous.		(31)
30 (29)	Inflorescences usually 1-flowered; each flower closely subtended by 2 leafy, often strongly convex bracteoles		10 Calystegia
+	Inflorescences with several flowers surrounded by an involucre of bracts		15 Ipomoea
31 (29)	Capsule 8-valved (in Chinese species); hairs stellate, 3- or more rayed, rarely absent		9 Jacquemontia
+	Capsule usually 4-valved (6-valved in some Ipomoea); hairs simple or 2-armed.		(32)
32 (31)	Stigmas linear, cylindric, clavate, or ovate-oblong and complanate.		(33)
+	Stigmas capitate, 2-globular (3-globular in some Ipomoea).		(34)
33 (32)	Pedicel with 2 persistent leafy bracts; outer 3 sepals enlarged in fruit; corolla pale yellow or whitish, center darker; stigmas ovate-oblong, complanate		8 Hewittia
+	Pedicel without bracts or bracts minute scales; sepals not enlarged in fruit, persistent; corolla red, rose, pink, or whitish, center paler; stigmas linear, cylindric, or clavate		11 Convolvulus
34 (32)	Pollen spiny, pantoporate.		(35)
+	Pollen smooth, 3-12-colpate, polyrugate, or pantoporate.		(36)
35 (34)	Corolla urceolate; filaments dilated basally into a concave scale, scales arched over ovary		16 Lepistemon
+	Corolla campanulate, funnelform, or salverform; filaments basally pubescent, glandular, or glabrous, not dilated into scales		15 Ipomoea
36 (34)	Herbs prostrate, tips often twining; inner 3 sepals tapering into slender points apically; leaf bases hastate, basal lobes dentate; pollen pantoporate		13 Xenostegia
+	Herbs twining or prostrate, or woody climbers; inner 3 sepals not tapering into points apically; leaf bases not as above; pollen 3-12-colpate or polyrugate		12 Merremia