1	Stems pilose, hirsute, tomentose, or villous and sometimes also hirtellous or villosulous, with pubescence sparsely to densely distributed and with some trichomes 1 mm or more		(2)
+	Stems glabrous to puberulent, strigillose, hispidulous, strigose, hirtellous, or pilosulous and sometimes hirsute or pilose in small scattered patches or lines, with trichomes generally all less than 1 mm		(9)
2 (1)	Plants scandent, climbing, or clambering; inflorescences terminal and in uppermost leaf axils, sometimes on very short lateral stems		(3)
+	Plants prostrate on ground, erect, or climbing; inflorescences terminal and/or axillary along middle or lower stem nodes		(5)
3 (2)	Inflorescences cymose, corymbiform-rounded; flowers all pedicellate, pedicels 1.5-3 mm.		42 H. obliquinervis
+	Inflorescences capitate, subcapitate, glomerulate, subglobose, or hemispherical; flowers sessile or subsessile		(4)
4 (3)	Heads solitary on peduncles or glomerulate along stem and/or along peduncles.		24 H. dianxiensis
+	Heads several in paniculate groups on each or at least most peduncles.		13 H. capitellata
5 (2)	Stipules entire; inflorescences and flowers sessile; Hainan, Taiwan		(6)
+	Stipules erose or 2-5-lobed or -setose; inflorescences and flowers sessile to pedicellate and/or pedunculate; mainland and Hainan		(7)
6 (5)	Annual herbs to 30 cm tall; calyx lobes ca. 1.5 mm; Taiwan.		11 H. butensis
+	Perennial subshrubs or shrubs to 1 m tall; calyx lobes 2.5-3 mm; Hainan.		64 H. wuzhishanensis
7 (5)	Low annual herbs, prostrate to weakly erect; leaves 6-10 mm wide; flowers few or solitary, subsessile to pedicellate; Hainan.		58 H. trinervia
+	Annual or perennial herbs or subshrubs, generally erect and robust; leaves 5-45 mm wide; flowers several to numerous, sessile to pedicellate in pedunculate heads or cymes		(8)
8 (7)	Flowers subsessile to pedicellate; glomerules or cymes subsessile to pedunculate; calyx lobes 1-1.2 mm.		34 H. lineata
+	Flowers sessile or subsessile; cymes or heads pedunculate; calyx lobes 0.3-1 mm.		62 H. vestita
9 (1)	Inflorescences mostly or all axillary or pseudoaxillary; stem apices generally vegetative		(10)
+	Inflorescences terminal, or terminal and in uppermost leaf axils		(34)
10 (9)	Inflorescences capitate, cymose, paniculate, fasciculate, or glomerulate, subsessile or on developed peduncles		(11)
+	Inflorescences sessile or subsessile, unbranched, i.e., glomerulate, capitate, congested-cymose, subcapitate, shortly fasciculate, or 1-flowered		(21)
11 (10)	Bracts lanceolate, ovate, elliptic, or broadly triangular, 1-12 mm, partly to fully enclosing flowers; flowers sessile to shortly pedicellate in heads or congested or somewhat lax cymes, or on pedicels to 1.5 mm; stipules triangular, 4-13 mm		(12)
+	Bracts reduced, absent, or narrow to triangular, 1-5 mm, not enclosing flowers; flowers separately pedicellate and/or pedunculate, solitary or in lax cymes; pedicels 1-30 mm; stipules reduced or triangular to truncate, 0.3-3 mm		(15)
12 (11)	Inflorescences congested-cymose to shortly paniculate or subglomerulate, sessile to pedunculate, peduncle to 2 cm; leaves 15-25 × 3-6 cm.		15 H. cathayana
+	Inflorescences capitate or glomerulate to laxly cymose, subsessile to pedunculate, peduncle to 8 cm; leaves 12-17 × 0.5-4 cm		(13)
13 (12)	Inflorescences capitate or glomerulate, on well-developed peduncles 2.5-7 cm.		9 H. bracteosa
+	Inflorescences cymose, branched, on peduncles 0.5-8 cm		(14)
14 (13)	Stipules 1.5-5 mm; calyx lobes 0.8-1.2 mm; corolla tube 2.2-3.5 mm.		1 H. acutangula
+	Stipules 8-13 mm; calyx lobes 2-3 mm; corolla tube 4.5-5 mm.		20 H. communis
15 (11)	Flowers several (i.e., ca. 5) to many in terminal and axillary lax cymes or panicles, separately pedicellate with pedicels 1-15 mm; leaves 7-35 mm wide		(16)
+	Flowers 1-5 per axil, all axillary on separate peduncles or in pedunculate cymes, pedicels and peduncles 1-30 mm; leaves 1-5 mm wide		(18)
16 (15)	Pedicels 4-15 mm; stipules triangular, ovate, or subtruncate, entire or glandular-serrulate or glandular-erose.		55 H. tenuipes
+	Pedicels 1-3 mm; stipules entire, 4-6-lobed, -setose, and/or ciliolate		(17)
17 (16)	Stipules 4-6-lobed or -setose.		3 H. assimilis
+	Stipules entire or ciliolate.		35 H. loganioides
18 (15)	Capsule with developed beak 1-1.5 mm, conical, longer than calyx lobes; stipules reduced, sheath portion reduced to a line or up to 0.3 mm; corolla tube 2-3 mm and lobes 0.5-1 mm.		30 H. herbacea
+	Capsule flat on top or with beak rounded to broadly angled, up to 0.5 mm, shorter than or equal to calyx lobes; stipules with sheath tubular to triangular, 0.5-2 mm; corolla tube 0.8-2.5 mm and lobes 0.8-1.5 mm		(19)
19 (18)	Stems quadrate to flattened with angles thickened to winged and usually pubescent to scaberulous; flowers 1-5 per peduncle, all pedicellate; stigmas and anthers included.		22 H. corymbosa
+	Stems terete to flattened or 4-angled when young, glabrous to rather evenly scaberulous or pubescent; flowers 1 or 2 in each stem axil, subsessile to pedicellate; stigmas and anthers exserted		(20)
20 (19)	Stems glabrous; peduncles and/or pedicels to 3 mm in flower, to 8 mm in fruit.		8 H. brachypoda
+	Stems puberulent and/or scaberulous; peduncles 4-20 mm.		25 H. diffusa
21 (10)	Stipules at flowering nodes with sheath 3-30 mm and these and/or leaf bases partially to fully enclosing and mostly hiding inflorescences		(22)
+	Stipules with sheath 4 mm or shorter (measured from line between bases of petioles), neither these nor leaf bases enclosing inflorescence		(25)
22 (21)	Leaves 15-30 × 5-10 cm; stipules narrowly triangular, 8-30 mm; calyx lobes 6-8 mm; corolla tube 14-16 mm; Hainan.		23 H. cryptantha
+	Leaves 2.5-12 × 1-4 cm; stipules broadly triangular to obovate, 3-10 mm; calyx lobes 1.5-6 mm; corolla tube 1.8-12 mm; mainland and Hainan		(23)
23 (22)	Calyx lobes 1.5-3 mm; corolla tube 1.8-2 mm.		33 H. lianshanensis
+	Calyx lobes 2-6 mm; corolla tube 6-12 mm		(24)
24 (23)	Leaves rounded to obtuse at base and sessile or subsessile; inflorescence terminal and pseudoaxillary; calyx lobes widest above middle.		40 H. merguensis
+	Leaves rounded to acute at base and petiolate, petioles 3-18 mm; inflorescences axillary; calyx lobes widest at or below middle.		47 H. platystipula
25 (21)	Leaves linear, narrowly elliptic, narrowly spatulate, linear-lanceolate, or narrowly elliptic-oblong, 0.8-13 mm wide, with margins mostly straight, with secondary veins not visible		(26)
+	Leaves narrowly to broadly elliptic, lanceolate, ovate, or elliptic-oblong, 4-45 mm wide, with margins curved, with secondary veins visible or not		(29)
26 (25)	Fruit compressed globose or subglobose; calyx lobes 1-1.5 mm; flowers solitary or 2 per node, pseudoaxillary.		8 H. brachypoda
+	Fruit ovoid to lanceoloid; calyx lobes 1-2.5 mm; flowers 1 to several per node, axillary, pseudoaxillary, and/or sometimes terminal		(27)
27 (26)	Inflorescences terminal and pseudoaxillary on short axillary stems; leaves linear to narrowly spatulate, 0.8-2 mm wide.		46 H. pinifolia
+	Inflorescences all axillary; leaves narrowly elliptic to linear, 1.5-13 mm wide		(28)
28 (27)	Calyx glabrous; flowers 1-3 per node; leaves 1.5-4 mm wide.		54 H. tenelliflora
+	Calyx densely hispidulous; flowers several per node; leaves 3-13 mm wide.		61 H. verticillata
29 (25)	Plants prostrate, regularly rooting at nodes; leaves 0.8-3.2 × 0.5-1.4 cm; flowers few, subsessile to pedicellate.		19 H. chrysotricha
+	Plants erect to procumbent, clambering, or prostrate, rooting only at or near base; leaves 1.2-12 × 0.3-4.5 cm; flowers few to numerous, sessile to pedicellate		(30)
30 (29)	Calyx lobes 1.5-4 mm		(31)
+	Calyx lobes 0.8-1.5 mm		(32)
31 (30)	Fruit indehiscent; inflorescences all produced at nodes below apex; corolla 3-4.5 mm.		33 H. lianshanensis
+	Fruit dehiscent septicidally then loculicidally; inflorescences terminal and axillary at uppermost stem nodes; corolla 4.5-5.5 mm.		59 H. uncinella
32 (30)	Leaves 1.2-4.5 cm wide, with secondary veins hardly or not visible; inflorescences axillary at upper nodes and often also terminal; corolla 3-4.2 mm.		48 H. prostrata
+	Leaves 0.3-3 cm wide, with secondary veins clearly evident; inflorescences at apex and/or nodes below apex; corolla 1-2.5 mm		(33)
33 (32)	Leaves subsessile to petiolate, 0.4-3 cm wide; stipules densely setose; inflorescences at nodes well below stem apex; corolla lobes 0.5-1 mm; widespread.		4 H. auricularia
+	Leaves sessile, 0.3-1 cm wide; stipules entire; inflorescences terminal and at uppermost nodes; corolla lobes ca. 0.2 mm; N Taiwan.		11 H. butensis
34 (9)	Flowers 5-merous; calyx lobes 3-3.5 mm.		28 H. hainanensis
+	Flowers 4-merous; calyx lobes 0.1-35 mm		(35)
35 (34)	Leaves linear, linear-lanceolate, narrowly elliptic, narrowly lanceolate, narrowly spatulate, or narrowly elliptic-oblong, consistently 0.8-5.5 mm wide		(36)
+	Leaves variously shaped, linear to elliptic, lanceolate, elliptic-oblong, or ovate, 3-120 mm wide with at least some leaves more than 5 mm wide		(39)
36 (35)	Flowers 2-12 in lax cymes; pedicels 3-20 mm.		32 H. koana
+	Flowers 3 to numerous in heads, fascicles, or congested to lax cymes; flowers sessile or on pedicels to 3 mm		(37)
37 (36)	Inflorescences with axes regularly dichotomous, 4-13 cm, with numerous flowers.		57 H. tetrangularis
+	Inflorescences up to 3 cm, capitate to cymose, with several flowers		(38)
38 (37)	Flowers on pedicels 0.5-1.2 mm; corolla tube 1.5-2.2 mm.		10 H. brevicalyx
+	Flowers sessile or on pedicels to 1 mm; corolla tube 3-4.2 mm.		46 H. pinifolia
39 (35)	Inflorescences 1-flowered or capitate, subcapitate, fascicled, or congested-cymose, with flowers few to numerous and sessile to subsessile or shortly pedicellate, in heads or congested to lax cymes		(40)
+	Inflorescences branched, cymose to paniculate, with flowers few to numerous, at least some of them regularly pedicellate (or separated on well-developed inflorescence axes)		(57)
40 (39)	Flowers solitary or 2-5 and fasciculate to very shortly cymose, sessile to shortly pedicellate; leaves 0.8-7 × 0.5-3.5 cm		(41)
+	Flowers 4 to numerous, sessile to shortly pedicellate in heads, congested cymes, or umbelliform cymes; leaves 1-12 × 0.6-4.5 cm		(42)
41 (40)	Calyx lobes ca. 4 mm, longer than or ± as long as corolla tube.		43 H. ovata
+	Calyx lobes 3-3.5 mm, much shorter than corolla tube.		50 H. pulcherrima
42 (40)	Inflorescences with peduncles, with 1 to several heads, with subtending bracts developed to leaflike or reduced		(43)
+	Inflorescences sessile or subsessile, in 1 head subtended by leaves or well developed to leaflike bracts		(48)
43 (42)	Calyx lobes 3-6 mm		(44)
+	Calyx lobes 0.3-4 mm		(45)
44 (43)	Leaves 4-5.5 × 0.6-2.6 cm.		65 H. xanthochroa
+	Leaves (at least well-developed ones) 8-12 × 3-4.5 cm.		66 H. yangchunensis
45 (43)	Corolla tube ca. 7 mm; inflorescence with 1 congested-cymose head (as far as known); flowers sessile.		63 H. wangii
+	Corolla tube 1-3 mm; inflorescence (at least usually) with 2-15 heads; flowers sessile or subsessile		(46)
46 (45)	Plants erect; corolla lobes shorter than tube, tube ca. 3 mm and lobes ca. 1.3 mm.		14 H. capituligera
+	Plants clambering to climbing; corolla lobes longer than tube, tube 1-2 mm and lobes 3-5 mm		(47)
47 (46)	Stems and leaves glabrescent or hirtellous, pilosulous, hispidulous, or tomentulose; calyx limb lobed for 1/3-3/4.		13 H. capitellata
+	Stems and leaves densely tomentulose or villous to glabrous; calyx limb deeply lobed.		24 H. dianxiensis
48 (42)	Calyx lobes ca. 35 mm; leaves 4-12 cm wide.		67 H. yazhouensis
+	Calyx lobes 1-5.5 mm; leaves 0.4-6 cm wide		(49)
49 (48)	Leaves with petioles 10-15 mm.		5 H. baotingensis
+	Leaves sessile or with petioles to 10 mm, at least some shorter than 10 mm		(50)
50 (49)	Calyx lobes 1-1.2 mm; corolla tube 2-3 mm.		48 H. prostrata
+	Calyx lobes 2-5.5 mm; corolla tube 3-12 mm		(51)
51 (50)	Corolla tube 9-12 mm.		40 H. merguensis
+	Corolla tube 3-6.5 mm		(52)
52 (51)	Stipules acute or aristate		(53)
+	Stipules laciniate or with several lobes or bristles		(55)
53 (52)	Leaves 0.4-1.2 cm wide, with petioles to 3 mm.		37 H. longipetala
+	Leaves 1.4-4.5 cm wide, with petioles to 10 mm		(54)
54 (53)	Stems glabrous; leaves 7-12 cm; corolla tube 4-5 mm.		45 H. paridifolia
+	Stems densely villous to hirtellous; leaves 2.5-6.2 cm; corolla tube 5.5-6.5 mm.		64 H. wuzhishanensis
55 (52)	Leaves puberulent to glabrous adaxially; flowers sessile or subsessile; corolla lobes 1.5-2 mm; fruit 1.8-2 mm in diam.		59 H. uncinella
+	Leaves glabrous or glabrescent adaxially; flowers sessile or on pedicels to 2 mm; corolla lobes 2-2.5 mm; fruit 2-2.5 mm in diam		(56)
56 (55)	Corolla tube ca. 5 mm; fruit ca. 2 mm in diam.		17 H. cheniana
+	Corolla tube ca. 3.5 mm; fruit ca. 2.5 mm in diam.		56 H. terminaliflora
57 (39)	Plants low annuals or perennials, vegetative part (and usually entire plant) mostly up to 15 cm tall, sometimes to 40 cm tall, often weak or scapose, often quite succulent; flowers few to numerous in small to diffuse cymes		(58)
+	Plants small to large, apparently perennials, vegetative portion usually at least 20 cm tall, robust, erect to clambering or climbing, usually not scapose, not or sometimes slightly succulent; flowers several to numerous in congested to expanded cymes or panicles		(62)
58 (57)	Leaves usually clustered at top of stem (i.e., at base of inflorescence) due to reduced internodes and appearing verticillate; stems densely pilosulous, puberulent, or villosulous and often glandular on uppermost nodes.		44 H. ovatifolia
+	Leaves generally distributed along stem in pairs, or entire stem with reduced internodes; stems glabrous to variously pubescent, not glandular		(59)
59 (58)	Hypanthium and fruit 4-winged, wings usually extending downward along pedicel.		49 H. pterita
+	Hypanthium and fruit smooth or with low ridges, or hypanthium sometimes narrowly winged in flower but becoming smooth as fruit develops		(60)
60 (59)	Calyx lobes ovate, relatively broad, sometimes with evident venation.		31 H. hermanniana
+	Calyx lobes triangular to lanceolate, generally narrow, not veined		(61)
61 (60)	Calyx limb lobed essentially to base, with tubular portion reduced or just a line; fruit with beak mostly as long as or longer than calyx lobes; plants not or somewhat succulent, weedy in various habitats.		6 H. biflora
+	Calyx limb with tube developed, lobed for 1/2-2/3, remaining developed and connected to lobes in fruit; fruit with beak much shorter than calyx lobes; plants succulent, mostly on seashores and rocks at low elevations.		53 H. strigulosa
62 (57)	Plants clambering, scandent, lianescent, or climbing		(63)
+	Plants erect		(66)
63 (62)	Leaves with secondary veins plane and generally not evident abaxially.		51 H. scandens
+	Leaves with secondary veins plane to prominulous and evident abaxially		(64)
64 (63)	Flowers pedicellate in dichotomous cymules, with pedicels 1-3.5 mm; axes and pedicels of inflorescence generally spreading at 60°-90°.		2 H. ampliflora
+	Flowers sessile to subsessile or pedicellate in congested to subcapitate cymules, with pedicels to 2 mm; axes and pedicels of inflorescence generally ascending, at angles less than 60°		(65)
65 (64)	Stems densely villous and/or tomentulose; flowers in distinct, discrete heads; calyx lobes generally erect.		24 H. dianxiensis
+	Stems glabrous to papillose, pilosulous, or velutinous-strigillose; inflorescence at least partly cymose; calyx lobes spreading to usually reflexed.		29 H. hedyotidea
66 (62)	Flowers all pedicellate, pedicels 4-15 mm		(67)
+	Flowers sessile to subsessile, mixed sessile and pedicellate, or all pedicellate, pedicels to 5 mm but most less than 4 mm		(68)
67 (66)	Calyx lobes 0.1-0.3 mm; corolla 1-1.5 mm.		18 H. chereevensis
+	Calyx lobes 1-1.5 mm; corolla 4.5-7 mm.		55 H. tenuipes
68 (66)	Inflorescence axes and pedicels spreading at 90° or more; leaves usually borne at only 2 or 3 stem nodes.		26 H. effusa
+	Inflorescence axes and pedicels ascending to slightly spreading, generally at angles less than 60° (or frequently to 90° or more in H. vachellii in fruit); leaves borne at few to numerous stem nodes		(69)
69 (68)	Stipules setose, lobed, or laciniate, with 2 to several narrow lobes, awns, or bristles (at least on lower nodes)		(70)
+	Stipules entire or sometimes with a terminal awn and/or serrate to serrulate-denticulate		(73)
70 (69)	Corolla tube longer than corolla lobes; inflorescences with several subcapitate to congested-cymose heads or cymules		(71)
+	Corolla lobes longer than corolla tube; inflorescences with few- to many-flowered cymes; pedicels 1-5 mm		(72)
71 (70)	Flowers sessile to subsessile.		14 H. capituligera
+	Flowers sessile and pedicellate, pedicels to 4 mm.		38 H. matthewii
72 (70)	Stipules 4-6-lobed or -setose.		3 H. assimilis
+	Stipules glandular-serrulate to 3-lobed or -setose.		39 H. mellii
73 (69)	Leaves with secondary veins prominulous and evident on abaxial surface.		39 H. mellii
+	Leaves with secondary veins plane and generally not evident on abaxial surface		(74)
74 (73)	Stems sharply angled to winged, at least on lower internodes; leaves sessile, often clasping at base.		1 H. acutangula
+	Stems rounded to flattened or angled, angles generally not sharp; leaves petiolate to subsessile, at base narrow to rounded but usually not clasping		(75)
75 (74)	Calyx lobes ca. 4 mm.		43 H. ovata
+	Calyx lobes 0.3-2.5 mm		(76)
76 (75)	Plants scapose, with leaves clustered at base; leaves 5-9 cm wide.		52 H. shenzhenensis
+	Plants with leaves distributed along stem; leaves 0.4-3.5 cm wide		(77)
77 (76)	Corolla tube 1.5-2.5 mm; calyx lobes 0.5-1.2 mm; inflorescence axes often becoming spiciform and/or scorpioid		(78)
+	Corolla tube 2.5-10 mm; calyx lobes 1-2.5 mm; inflorescence axes generally dichasial		(79)
78 (77)	Calyx lobes 0.8-1.2 mm; leaves with secondary veins 4-6 pairs.		21 H. consanguinea
+	Calyx lobes ca. 0.5 mm; leaves with secondary veins ca. 3 pairs.		36 H. longiexserta
79 (77)	Corolla with tube 4-10 mm, lobes 1/2 as long as tube or shorter		(80)
+	Corolla with tube 2.5-4 mm, lobes shorter than tube but more than 1/2 as long as tube		(82)
80 (79)	Corolla white or pink, with tube markedly funnelform.		16 H. caudatifolia
+	Corolla pink to purple, with tube cylindrical to slightly funnelform		(81)
81 (80)	Corolla tube ca. 6 mm.		27 H. exserta
+	Corolla tube 7-10 mm.		41 H. minutopuberula
82 (79)	Pedicels to 4 mm; corolla tube 3.5-4 mm and lobes 2-3 mm.		38 H. matthewii
+	Pedicels to 1.5 mm; corolla tube 2.5-3.5 mm and lobes 2-2.2 mm		(83)
83 (82)	Inflorescences narrowly cylindrical to pyramidal, axes ascending; fruit 2-3 mm in diam.		12 H. cantoniensis
+	Inflorescences broadly pyramidal to rounded, axes ascending to spreading at 90° or more; fruit ca. 1.8 mm in diam.		60 H. vachellii