1	Petals and stamens deciduous after anthesis (rarely tardily); shrubs or rarely subshrubs; plant always without dark glands		(2)
+	Petals and stamens persistent after anthesis; herbs; plant very often with dark glands		(39)
2 (1)	Styles completely united; anthers ± basifixed		(3)
+	Styles free or partly united; anthers markedly dorsifixed		(6)
3 (2)	Sepals 1-3 mm, mostly broadly ovate to oblong, usually obtuse to rounded, without distinct midvein.		33 H. geminiflorum
+	Sepals 3.5-10 mm, mostly lanceolate or narrowly elliptic to linear, acute to subacute (or rarely rounded), often with distinct midvein		(4)
4 (3)	Stems 4-angled or 4-winged when mature; leaves usually narrowly elliptic to lanceolate, acute to subacute.		34 H. subalatum
+	Stems terete when mature; leaves ovate to elliptic or obovate, subacute to rounded		(5)
5 (4)	Sepals obovate to lanceolate, 7-10 mm, ascending in fruit; petals 10-20 mm; leaves ovate to elliptic.		31 H. formosanum
+	Sepals linear-lanceolate, 3.5-8 mm, reflexed in fruit; petals 20-28 mm; leaves elliptic to obovate.		32 H. nakamurae
6 (2)	Leaves (at least upper) sessile, thickly leathery, without visible reticulate venation abaxially; styles free		1 H. augustinii
+	Leaves all subsessile or short petiolate or, if sessile, then visibly ± densely reticulate-veined abaxially and/or with styles ± united		(7)
7 (6)	Stem prostrate to ascending or pendent, forming low mats or clumps; styles ca. as long as ovary.		2 H. reptans
+	Stem erect to straggling, not mat-forming		(8)
8 (7)	Styles partly coherent or ± united, at least 1.4 × as long as ovary; leaves usually densely reticulate-veined abaxially (except in		8 H. longistylum).
+	Styles free, usually less than 1.4 × as long as ovary; leaves usually laxly or not visibly reticulate-veined abaxially		(14)
9	Styles coherent in lower half at first		(10)
+	Styles united nearly to apex; petiole absent or to 1.5 mm (except in		4 H. monogynum).
10 (9)	Leaves sessile, blade ovate-oblong to ovate, venation densely reticulate.		3 H. griffithii
+	Leaf petiole 1.5-2 mm, blade oblong to elliptic, venation laxly reticulate.		5 H. cohaerens
11	Suffrutex; petals and stamens tardily deciduous.		7 H. elatoides
+	Shrub; petals and stamens soon deciduous		(12)
12 (11)	Leaves without visible reticulate venation abaxially, 1-3.3 cm; inflorescence always 1-flowered.		8 H. longistylum
+	Leaves densely reticulate-veined abaxially, (2-)3-11 cm; inflorescence 1-30-flowered, terminal on long shoots		(13)
13 (12)	Leaves with base cuneate to rounded, or if cordate then apex rounded; leaf blade usually broadest at or above middle.		4 H. monogynum
+	Leaves with base cordate-amplexicaul, apex acute to acuminate; leaf blade elliptic-ovate to broadly ovate.		6 H. prattii
14 (8)	Leaves sessile, densely reticulate-veined.		3 H. griffithii
+	Leaves subsessile or petiolate, laxly or not visibly reticulate-veined		(15)
15 (14)	Petals waxy, golden yellow; stamens 0.25-0.35 × as long as petals, densely crowded		(16)
+	Petals not waxy, golden to pale yellow; stamens longer than 0.35 × as long as petals or, if equal or shorter, then not densely crowded		(18)
16 (15)	Sepals spreading-incurved in bud and in fruit, often becoming markedly ribbed; capsule ovoid to ovoid-conic.		11 H. hookerianum
+	Sepals erect to spreading in bud, spreading to recurved in fruit, not ribbed; capsule narrowly ovoid-cylindric to narrowly ellipsoid-cylindric		(17)
17 (16)	Leaves narrowly ovate to lanceolate, base rounded, with dense abaxial glands and short laminar glandular streaks; sepals spreading in bud, reflexed in fruit.		9 H. fosteri
+	Leaves narrowly lanceolate, base cuneate, without abaxial glands, with long laminar glandular streaks; sepals erect in bud, spreading in fruit.		10 H. wardianum
18 (15)	Sepals spreading to recurved at anthesis and in fruit; leaf venation often markedly reticulate or at least conspicuous abaxially (except in		13 H. acmosepalum).
+	Sepals erect and outcurving or appressed in flower and fruit; leaf venation neither visibly reticulate nor conspicuous		(25)
19	Leaves elliptic to oblong or (lower) oblanceolate (broadest at or above middle), never triangular; sepals deciduous or outcurving		(20)
+	Leaves ovate or lanceolate to oblong-lanceolate (broadest below middle), sometimes triangular; sepals persistent, spreading to recurved		(21)
20 (19)	Leaves subsessile, narrowly elliptic, markedly reticulate-veined; sepals deciduous, spreading, ovate to elliptic, often leaflike; capsule 16-21 mm, purplish red when maturing.		12 H. subsessile
+	Leaves petiolate (0.5-1.5 mm), narrowly elliptic to oblong, not reticulate-veined but with conspicuous intramarginal vein; sepals persistent, ovate to narrowly lanceolate, not leaflike; capsule 9-15 mm, bright red at first when maturing.		13 H. acmosepalum
21 (19)	Sepals elliptic to oblong or foliose; leaves lanceolate to ovate-lanceolate, ± triangular, with venation (secondary and sometimes tertiary) conspicuous		(22)
+	Sepals lanceolate-elliptic to lanceolate (or rarely leaflike); leaves lanceolate to oblong or ovate, not triangular, usually without conspicuous venation		(23)
22 (21)	Petals obovate-oblanceolate, flowers stellate; stamens ca. 3/5 as long as petals; styles 0.85-1 × as long as ovary; leaves densely glaucous abaxially, petiole 0.5-2 mm.		14 H. maclarenii
+	Petals broadly obovate to obovate-suborbicular, flowers shallowly to deeply cupped; stamens 0.35-0.4 × as long as petals; styles 0.35-0.7 × as long as ovary; leaves thinly or not glaucous abaxially, petiole 2-4 mm.		15 H. choisyanum
23 (21)	Styles shorter than ovary; inflorescence 1(-3)-flowered; leaves triangular-lanceolate to triangular-ovate.		18 H. curvisepalum
+	Styles ca. as long as ovary or more; inflorescence (1-)3-14-flowered; leaves oblong-lanceolate or lanceolate to narrowly ovate		(24)
24 (23)	Styles outcurved distally; inflorescence branches usually relatively stout; leaf abaxial glands usually few or none.		16 H. lancasteri
+	Styles straight or flexuous; inflorescence branches relatively slender; leaf abaxial glands dense.		17 H. stellatum
25 (18)	Sepals with broad hyaline margin; stems erect to arching with ± numerous lateral branches, often frondose, markedly ancipitous (2-edged) when young		(26)
+	Sepals without or with a very narrow hyaline margin; stems erect to spreading but not frondose, not or scarcely ancipitous (2-edged) when young		(30)
26 (25)	Sepals entire, at least outer broadly elliptic or broadly oblong to circular, obtuse to rounded; stems erect, not frondose.		19 H. henryi
+	Sepals eroded-denticulate or, if entire, then elliptic or narrowly oblong to oblanceolate, rounded to acute; stems erect or spreading, sometimes frondose		(27)
27 (26)	Sepals eroded-denticulate to subentire, usually apiculate, broadly elliptic to broadly ovate; leaf apex usually apiculate-obtuse to rounded		(28)
+	Sepals entire, rarely apiculate, elliptic to narrowly oblong or obovate-spatulate; leaf apex acute to rounded-apiculate		(29)
28 (27)	Stems erect to arching or rarely divaricate, not frondose, ± persistently 4-lined; leaf-apex acute to rounded but rarely apiculate; capsule 10-14 mm.		19 H. henryi
+	Stems spreading, sometimes frondose, soon 2-lined; leaf-apex obtuse to rounded, always apiculate; capsule 9-11 mm.		20 H. patulum
29 (27)	Flower buds acute to obtuse; sepals subacute to rounded; stems erect or arching, not or only distally frondose.		19 H. henryi
+	Flower buds obtuse to rounded; sepals rounded; stems arching, often frondose.		21 H. uralum
30 (25)	Stems slender, spreading especially when young; capsules lobed or grooved		(31)
+	Stems stout, erect to arching but not spreading; capsules not lobed or grooved		(32)
31 (30)	Styles 0.5-0.85 × as long as ovary; sepals with inconspicuous midvein, outcurving in fruit; flower buds ovoid to ovoid-pyramidal, obtuse to acute.		22 H. lagarocladum
+	Styles 1.5-1.8 × as long as ovary; sepals with conspicuous midvein, erect in fruit; flower buds narrowly ovoid, acute to acuminate.		23 H. wilsonii
32 (30)	Styles 1.2-1.35 × as long as ovary; petals spreading to reflexed, apiculus acute; sepals acute, spreading in fruit.		28 H. kouytchense
+	Styles 0.6-1.1 × as long as ovary; petals incurved to spreading, apiculus obtuse to rounded; sepals acute to rounded, spreading to erect in fruit		(33)
33 (32)	Sepals ± spreading in bud and sometimes in fruit; ovary and capsule narrowly cylindric-ellipsoid to broadly pyramidal-ovoid; leaf apex acute to rounded-apiculate.		24 H. beanii
+	Sepals erect in bud and erect or incurved in fruit; ovary and capsule ovoid to subglobose or pyramidal-ovoid; leaf apex obtuse to rounded		(34)
34 (33)	Leaves broadly elliptic or very broadly elliptic-oblong to orbicular, margin plane		24 H. beanii
+	Leaves lanceolate to broadly ovate or, if circular, then margin undulate		(35)
35 (34)	Branches spreading; sepals acute to rounded-apiculate; stamens ca. 0.4 × as long as petals; leaves with lower 1 or 2 pairs of main lateral veins usually free.		25 H. addingtonii
+	Branches erect to arching; sepals acute to rounded; stamens ca. 0.5 × as long as petals or more, or, if relatively shorter, then sepals rounded; leaves with all main lateral veins incurved to join next upper vein		(36)
36 (35)	Ovary and capsule subglobose to broadly or narrowly ovoid; leaves lanceolate to ovate, rhombic, or subcircular; sepal margin not or scarcely hyaline		(37)
+	Ovary and capsule pyramidal-ovoid; leaves triangular-lanceolate or lanceolate-oblong to ± broadly triangular-ovate; sepal margin distinctly hyaline		(38)
37 (36)	Sepals ovate to broadly elliptic, obtuse or apiculate to rounded; capsule broadly ovoid; flowers 4-6 cm in diam.; stamens (0.5-)0.6-0.7 × as long as petals; leaf ratio (l:w) = 1.8-2.5, base cuneate to rounded, margin plane.		26 H. latisepalum
+	Sepals narrowly elliptic or oblong to obovate, usually rounded; capsule narrowly ovoid; flowers 2.5-3.5 cm in diam.; stamens 0.35-0.45(-0.6) × as long as petals; leaf ratio (l:w) = 1.1-1.6, base truncate to subcordate or, if cuneate, then margin undulate.		27 H. bellum
38 (36)	Sepals acute to obtuse, outcurved in fruit; stems ± persistently 4-lined; leaves usually lanceolate or lanceolate-oblong to ovate-oblong; petals spreading to reflexed; flower buds subacute to apiculate.		29 H. pseudohenryi
+	Sepals rounded or rarely apiculate, erect in fruit; stems soon terete; leaves triangular-ovate or, more rarely, lanceolate or ± broadly ovate; petals incurved; flower buds rounded.		30 H. forrestii
39 (1)	Styles (4 or)5; stamen fascicles 5, free; dark glands absent		(40)
+	Styles (2 or)3(or 4); stamen fascicles usually apparently 3 or stamens irregularly arranged; dark glands usually present		(41)
40 (39)	Leaf apex acute to obtuse, blade mostly lanceolate to elliptic-oblong or linear; mature stem internodes sharply 4-lined to narrowly 4-winged.		35 H. ascyron
+	Leaf apex rounded to shallowly retuse, blade oblong to oblong-lanceolate, oblong-ovate, or triangular-oblong; mature stem internodes partially 2- or 4-lined or terete.		36 H. przewalskii
41 (39)	Dark glands absent; stem internodes 4-lined or narrowly 4-winged; stamens irregularly arranged		(42)
+	Dark (black or reddish) glands present on at least sepals and/or anthers or leaves; stem internodes 2-lined or terete; stamens usually apparently 3(or 4)-fascicled		(43)
42 (41)	Stamens 30-40, styles 0.7-1.8 mm; stems branching strictly from base or unbranched, not rooting; leaves ovate-lanceolate to linear (l:w = 3-5).		63 H. gramineum
+	Stamens 5-30, styles 0.4-1 mm; stems usually branching ± widely along most of stem, rooting at base; leaves usually ovate or triangular-ovate to oblong or elliptic (l:w = 1.5-2.5).		64 H. japonicum
43 (41)	Anther gland amber; dark glands sometimes present on leaves but not forming inframarginal row; seeds with testa ± markedly papillose		(44)
+	Anther gland dark; dark glands nearly always forming inframarginal row on leaves; seeds with testa reticulate to foveolate		(46)
44 (43)	Stem and leaves pubescent; inflorescence usually pyramidal; sepals gland-fringed; stems creeping and rooting.		62 H. hirsutum
+	Stem and leaves glabrous; inflorescence ± cylindric or flat-topped; sepal margin with few or no glands; stems not creeping or rooting		(45)
45 (44)	Inflorescence ± cylindric; stem smooth.		60 H. elongatum
+	Inflorescence flat-topped; stem scabrid with red-gland-tipped emergences.		61 H. scabrum
46 (43)	Stem internodes markedly 2(or 4)-lined		(47)
+	Stem internodes terete or rarely 2-4(-6)-lined when stems weak or slender		(50)
47 (46)	Capsule valves with central linear and lateral vesicular glands; stems much branched distally with branching divergent-ascending and black glands confined to lines.		57 H. perforatum
+	Capsule valves with linear glands only; stems sparingly branched below inflorescence with branching virgate and black glands not confined to lines or completely absent		(48)
48 (47)	Stems with dark glands, erect; capsule broadly ovoid to narrowly conic; stamens apparently 3-fascicled.		56 H. attenuatum
+	Stems without dark glands, suberect to ascending; capsule broadly to narrowly ovoid; stamens irregularly arranged		(49)
49 (48)	Sepals without dark laminar streaks or, if present, then apex obtuse; leaves variable in size and shape but, if less than 15 mm, then narrow (l:w = 4-12).		58 H. nagasawae
+	Sepals with dark laminar streaks, apex acute to subacuminate; leaves short (4-12 mm) and broad (l:w = 2-3.1).		59 H. nokoense
50 (46)	Leaf pairs perfoliate; capsule valves with vesicular glands only.		37 H. sampsonii
+	Leaf pairs free; capsule valves with longitudinal vittae only		(51)
51 (50)	Leaves and sometimes sepals and petals with laminar glands dark only		(52)
+	Leaves, sepals, and petals with laminar glands (if present) partly or completely pale		(55)
52 (51)	Sepals entire, sepals and petals 5		(53)
+	Sepals glandular-ciliate or, if entire, then sepals and petals 4		(54)
53 (52)	Leaves sessile, triangular-ovate to narrowly elliptic, not minutely papillose; stems usually unbranched below inflorescence.		55 H. erectum
+	Leaves petiolate, oblong to obovate, adaxially minutely papillose; stems branching from most nodes.		53 H. enshiense
54 (52)	Styles 4-5 mm; capsule broadly ovoid; uppermost leaf pair bracteose; sepals and petals 5.		47 H. trigonum
+	Styles 1.5-3 mm; capsule globose; uppermost leaf foliar; sepals and petals 4.		50 H. monanthemum
55 (51)	Sepals entire, oblong to ovate-oblong, obtuse (or rarely acute) to rounded, not leaflike		(56)
+	Sepals dark-gland-fringed or, if entire, then acute or leaflike		(58)
56 (55)	Leaf laminar glands mostly black.		53 H. enshiense
+	Leaf laminar glands all or mostly pale or absent		(57)
57 (56)	Leaves without or rarely with a few large pale or pale and dark laminar glands, main lateral veins 2- or 3-paired.		52 H. faberi
+	Leaves with dense small pale laminar glands; main lateral veins 3-4-paired.		54 H. taihezanense
58 (55)	Leaves with laminar glands large, prominent, dense; leaf blade usually lanceolate or narrowly elliptic to linear or obovate; marginal glands round-topped		(59)
+	Leaves with laminar glands small, not prominent, often sparse, or absent; leaf blade ovate or triangular-ovate to elliptic, oblong, or circular; marginal glands flat-topped		(65)
59 (58)	Sepals entire or occasionally with few glandular cilia; bracts without or with short glandular auricles; leaves entire		(60)
+	Sepals regularly glandular-ciliate; bracts and sometimes upper leaves glandular-ciliate and with glandular-ciliate auricles		(62)
60 (59)	Leaves with petiole 1-10 mm, base usually cuneate to angustate; sepals with few irregularly spaced marginal glands or none; styles 1-2.5 mm, 0.7-1.3 × as long as ovary.		39 H. petiolulatum
+	Leaves sessile or with broad petiole to 1 mm, base subcordate-amplexicaul to cuneate; sepals with marginal glands in ± regular row; styles 2.5-10 mm, 1.5-3 × as long as ovary		(61)
61 (60)	Leaves oblong-lanceolate to narrowly oblong, 5-13 mm wide; sepal and petal laminar glands pale.		38 H. seniawinii
+	Leaves oblong-ovate, 10-16 mm wide; sepal and petal laminar glands black.		40 H. hubeiense
62 (59)	Leaves broadly ovate-oblong or broadly elliptic to suborbicular, 6-14 mm, entire, apex rounded, without glandular auricles.		44 H. kingdonii
+	Leaves lanceolate to oblong-lanceolate or linear, 1-6 cm, sometimes glandular-ciliate, apex acute to obtuse, the upper with glandular auricles		(63)
63 (62)	Styles ca. 1.7 mm, shorter than ovary; sepals ovate, 3-5 mm; leaves ternate.		43 H. austroyunnanicum
+	Styles 3-18 mm, longer than ovary; sepals lanceolate to oblong, 5-9 mm; leaves paired		(64)
64 (63)	Styles 3-7 × as long as ovary, 6-18 mm; pedicels 0.5-3(-6) mm; petal laminar glands pale.		41 H. hengshanense
+	Styles ca. 2 × as long as ovary, 3-8 mm; pedicels 3-12 mm; petal laminar glands all or mostly dark.		42 H. elodeoides
65 (58)	Leaves elliptic-oblong to lanceolate and/or with glandular-ciliate margin and auricles		(66)
+	Leaves (triangular-)ovate to elliptic or oblong or obovate to oblanceolate, entire (uppermost pair sometimes bracteose)		(67)
66 (65)	Ovary and capsule ellipsoid to cylindric-ellipsoid; leaves all sessile, entire; sepals lanceolate to narrowly oblong-elliptic, acute, glandular-ciliate.		45 H. daliense
+	Ovary and capsule ovoid to globose; leaves (at least upper) glandular-ciliate, lower often petiolate; sepals broadly oblong or ± broadly elliptic, acute to obtuse, glandular-ciliate to -laciniate.		46 H. wightianum
67 (65)	Ovary and capsule ovoid (or ovary ellipsoid) to subglobose; styles 1.5-3 mm; uppermost leaf pair leaflike		(68)
+	Ovary and capsule ± ellipsoid or, if ovoid-ellipsoid to broadly ovoid, then styles 4-5 mm; uppermost leaf pair bracteose		(69)
68 (67)	Leaves (at least uppermost) sessile; sepals with pale laminar glandular lines or, if dark, then margin glandular-ciliate; ovary ovoid to subglobose.		50 H. monanthemum
+	Leaves all short petiolate; sepals all with dark linear laminar glands, entire; ovary ellipsoid.		51 H. subcordatum
69 (67)	Styles 4-5 mm; capsule broadly ovoid; leaves all sessile, blade oblong to triangular-ovate.		47 H. trigonum
+	Styles 2-3 mm; capsule ± ellipsoid; some or all leaves petiolate, blade triangular-ovate to elliptic or oblanceolate to obovate		(70)
70 (69)	Stem unbranched below apical node or with a few short suberect branches; styles usually longer than ovary; sepals usually without dark laminar glands.		48 H. ludlowii
+	Stem nearly always with long ± spreading branches from up to 5 nodes; styles usually (?always) ca. as long as ovary or less; sepals usually with dark laminar glands.		49 H. himalaicum