Dichotomous key to genera

The following dichotomous key reflects the traditional classification of the genera of the Apiaceae into subfamilies, tribes, and subtribes. This classification relies heavily on characters of fruit morphology and anatomy, many of which are subject to convergent evolution (e.g., for fruit dispersal strategies). The long-held understanding that this gives rise to artificial, heterogeneous assemblages has been verified by recent molecular studies of DNA sequences. For this reason tribes and subtribes are not formally recognized in the following account; however, they are indicated in the dichotomous key and the traditional order of genera is largely retained. It is worth noting that the generic grouping within the three subfamilies is well supported by molecular evidence, the exception being Hydrocotyle and Centella which are most likely derived, herbaceous members of the Araliaceae and not Hydrocotyloideae (the residue of this subfamily is restricted to the S hemisphere).

1	Stem creeping or ascending, rarely erect; leaves simple; leaf blade reniform or rounded-cordate; umbels simple; endocarp woody; vittae obscure or distinct, borne in the ribs, not in the furrow (subfam. Hydrocotyloideae).		(2)
+	Stem usually erect, sometimes reduced, not creeping; leaves compound or simple; umbels compound, rarely simple or subracemous-branched to capitate; endocarp not woody; vittae distinct to obscure, borne in the primary ribs or furrows.		(4)
2 (1)	Fruit flattened dorsally, carpophore shortly bifid at the apex (tribe Mulineae).		3 Dickinsia
+	Fruit flattened laterally, commissure narrow, carpophore absent (tribe Hydrocotyleae).		(3)
3 (2)	Bracts absent; petals valvate; dorsal fruit ribs prominent, lateral ribs obscure, surface smooth.		1 Hydrocotyle
+	Bracts present; petals imbricate; dorsal and lateral fruit ribs prominent, surface wrinkled.		2 Centella
4 (1)	Leaves simple, usually palmately divide to shallowly lobed; umbels simple or compound, occasionally capitate; fruit covered with scales, tubercles or prickles, rarely glabrous; styles elongate (subfam. Saniculoideae).		(5)
+	Leaves compound, rarely simple; umbels compound, very rarely simple (acaulescent plants with sessile terminal umbel appearing simple); rays numerous, well developed; fruit glabrous or pubescent, sometimes fine-prickly or spiny; styles short or long (subfam. Apioideae).		(6)
5 (4)	Basal leaves orbicular, rounded-cordate or cordate-pentagonal, usually palmately lobed; flowers polygamous, umbels in racemous, cymous or corymbose inflorescences.		4 Sanicula
+	Basal leaves long-elliptic, lanceolate or oblanceolate, undivided; flowers bisexual, borne in capitate inflorescences.		5 Eryngium
6 (4)	Fruit with both primary and secondary ribs, secondary ribs prominent or winged.		(7)
+	Fruit with primary ribs, secondary ribs absent (except Aphanopleura and Cuminum).		(8)
7 (6)	Ribs not spinose (tribe Laserpiteae).		99 Saposhnikovia
+	Ribs spinose (tribe Dauceae).		100 Daucus
8 (6)	Commissure face of seed plane, rarely slightly concave.		(9)
+	Commissure face of seed deeply concave or sulcate.		(73)
9 (8)	Fruit ribs equal, mericarp orbicular or subpentagonal cross section, usually slightly laterally compressed (tribe Ammineae).		(10)
+	Lateral ribs of fruit winged, broader than the dorsal and intermediate ribs, mericarp slightly to strongly dorsally compressed (tribe Peucedaneae).		(53)
10 (9)	Primary ribs of fruit filiform, commissure narrow (subtribe Carinae).		(11)
+	Fruit ribs prominent to narrowly winged, commissure moderately broad (subtribe Seselinae).		(35)
11 (10)	Leaves simple, undivided.		34 Bupleurum
+	Leaves divided, ternate, pinnate or pinnately decompound.		(12)
12 (11)	Fruit both with primary and secondary ribs; vittae large, 1 in each furrow.		(13)
+	Fruit with primary ribs only; vittae 1 to several in each furrow, rarely absent.		(14)
13 (12)	Fruit ovoid, secondary ribs clavate-hispid or papillose.		35 Aphanopleura
+	Fruit oblong-ellipsoid, secondary ribs setulose.		36 Cuminum
14 (12)	Petals attenuate or thickening at base, or apex caudate to linear.		(15)
+	Petals neither thickening at base nor apex caudate.		(16)
15 (14)	Petals thickening at base, often sac-like.		46 Pternopetalum
+	Petals caudate or linear at apex.		49 Acronema
16 (14)	Fruit oblong-ellipsoid or ellipsoid, base rounded.		(17)
+	Fruit ovoid-globose, base often cordate.		(24)
17 (16)	Calyx teeth conspicuous, ovate-triangular.		55 Carlesia
+	Calyx teeth minute or obsolete.		(18)
18 (17)	Fruit vittae obscure; styles long, very reflexed.		51 Aegopodium
+	Fruit vittae conspicuous; styles short or long, less reflexed.		(19)
19 (18)	Styles long, reflexed.		(20)
+	Styles short, erect or divaricate.		(21)
20 (19)	Vittae 1 in each furrow, 2 on commissure.		43 Ammi
+	Vittae 3–4 in each furrow, 6–8 on commissure.		47 Chamaesciadium
21 (19)	Leaves ternate-parted, leaflets rhombic-ovate, margin doubly serrate.		42 Cryptotaenia
+	Leaves 2–4-pinnatisect, ultimate segments linear or lanceolate-linear, entire.		(22)
22 (21)	Ultimate leaf segments lanceolate-linear, 20–90 × 1–5 mm.		52 Seselopsis
+	Ultimate leaf segments narrowly linear, 2–10 × 0.2–1 mm.		(23)
23 (22)	Bracts and bracteoles membranous.		53 Hyalolaena
+	Bracts and bracteoles usually absent, rarely few, not membranous.		44 Carum
24 (16)	Calyx teeth conspicuous, ovate-triangular; vittae 1 in each furrow.		39 Cicuta
+	Calyx teeth obsolete or minute; vittae 1 to several in each furrow.		(25)
25 (24)	Vittae 2 to numerous (rarely 1) in each furrow, 4–6 on commissure.		(26)
+	Vittae usually 1 in each furrow, 2 on commissure.		(30)
26 (25)	Vittae small, numerous, forming a continuous ring encircling the seed; fruit wall thick, corky.		57 Berula
+	Vittae large, 2–4 in each furrow, not forming a ring encircling the seed; fruit wall not thick, corky.		(27)
27 (26)	Bracts membranous, pale green or absent.		(28)
+	Bracts lanceolate to linear, green, persistent.		(29)
28 (27)	Bracts absent.		40 Trachyspermum
+	Bract membranous.		54 Nothosmyrnium
29 (27)	Plants of wet, swampy ground; leaves pinnate to pinnatisect.		58 Sium
+	Plants of dry ground; leaves undivided, 3-parted, ternate-pinnate or ternate-pinnatifid.		48 Pimpinella
30 (25)	Petals base clawed, unequal, the outer usually radiant.		45 Sinocarum
+	Petals base not clawed, usually equal.		(31)
31 (30)	Fruit surface villous, verrucose or papillose.		(32)
+	Fruit glabrous or almost so.		(33)
32 (31)	Fruit surface densely villous.		41 Eriocycla
+	Fruit surface verrucose or papillose.		50 Harrysmithia
33 (31)	Branches opposite or verticillate; leaves 2–3-pinnate.		38 Petroselinum
+	Branches alternate; leaves pinnate or ternate-pinnate.		(34)
34 (33)	Plants biennial or perennial, often aquatic or amphibious, taproots stout or with creeping rootstocks, rooting at nodes.		37 Apium
+	Plants annual, terrestrial, taproots slender, without creeping rootstock, not rooting at nodes.		56 Cyclospermum
35 (10)	Semiaquatic or marshland herbs; outer petals of umbellule usually conspicuously radiant; lateral fruit ribs corky-thickened, subtriangular.		61 Oenanthe
+	Terrestrial herbs; outer petals of umbellule not radiant; lateral fruit ribs not corky (rarely corky-thickened, see Cortiella, Pterygopleurum).		(36)
36 (35)	Plants strongly aromatic throughout; leaves decompound-pinnatisect, ultimate segments filiform, less than 1 mm wide; petals yellow.		(37)
+	Plants not strongly aromatic; leaves 1–3-pinnate or pinnately decompound, ultimate segments broad or narrow, more than 1 mm wide; petals white, purplish, purple, creamy white or greenish white, not strongly yellow (except yellow in Silaum).		(38)
37 (36)	Fruit oblong, terete; ribs equal; stem gray-green.		63 Foeniculum
+	Fruit ovate-ellipsoid, slightly flattened dorsally; lateral ribs more or less broader than the dorsal; stem green.		64 Anethum
38 (36)	Fruit oblong or ellipsoid, slightly to strongly flattened dorsally; mericarps not pentagonal in cross section; ribs unequal, lateral wings much broader than dorsal.		(39)
+	Fruit ovoid-oblong or ellipsoid, slightly flattened laterally or dorsally, usually terete; mericarp pentagonal in cross section; all ribs equal or subequal.		(43)
39 (38)	Bracts leaf-like, 1–2-pinnate.		(40)
+	Bracts absent or present, usually entire, rarely divided.		(42)
40 (39)	Fruit flat-globose, all ribs broadly winged, lateral ribs broadest, wings cork-spongy.		75 Cortiella
+	Fruit ellipsoid, dorsal ribs filiform, narrowly winged, lateral ribs more broadly winged than the dorsal, not cork-spongy.		(41)
41 (40)	Acaulescent or subacaulescent; bracteoles ca. equaling umbellules.		76 Cortia
+	Caulescent, stem usually above 25 cm; bracteoles 2–3 × umbellules.		77 Oreocomopsis
42 (39)	Lateral fruit ribs broadly winged, wings more than 2 × width of dorsal ribs; calyx teeth well developed, often equaling or exceeding the stylopodium.		69 Selinum
+	Lateral fruit ribs winged, wings equaling or slightly broader than the dorsal; calyx teeth usually minute or obsolete.		72 Ligusticum
43 (38)	Fruit ribs irregularly denticulate, denticles stiffly membranous.		70 Stenocoelium
+	Fruit ribs entire, denticles absent.		(44)
44 (43)	Bracts and bracteoles leaf-like, 1–2-pinnate.		62 Schulzia
+	Bracts entire; bracteoles entire, rarely pinnate.		(45)
45 (44)	Rays much reduced, umbels capitate (appearing simple); petals purplish-brown.		74 Haplosphaera
+	Rays well developed, umbels not capitate; petals white, creamy-white or purplish.		(46)
46 (45)	Calyx teeth well developed, subulate, lanceolate or triangular-ovate.		(47)
+	Calyx teeth minute or obsolete.		(49)
47 (46)	Fruit ribs filiform, prominent, obtuse or acute but neither thickened nor corky-dilated at base.		59 Libanotis
+	Fruit ribs winged, wings thickened or corky-dilated at base.		(48)
48 (47)	Leaves 1–2-pinnate or ternate-pinnate, ultimate segments long-lanceolate, entire; fruit ribs corky-dilated at base.		66 Pterygopleurum
+	Leaves 2–3-pinnate, ultimate segments ovate-lanceolate to linear, usually serrate or lobed; wings thickened but not corky dilated at base.		73 Pachypleurum
49 (46)	Bracteoles fused at base or up to the middle.		(50)
+	Bracteoles separate, not fused at base.		(51)
50 (49)	Stylopodium conic or depressed, margin not lobed; fruit ovoid or ellipsoid.		60 Seseli
+	Stylopodium flat, margin deeply lobed; fruit oblong.		67 Lithosciadium
51 (49)	Fruit ribs narrowly winged, wings hollow.		71 Cenolophium
+	Fruit ribs acute or winged, wings not hollow.		(52)
52 (51)	Petals yellow; fruit vittae numerous, small, obscure at maturity.		65 Silaum
+	Petals white or pinkish; fruit vittae 1 in each furrow, 2 on commissure, conspicuous at maturity.		68 Cnidium
53 (9)	Lateral mericarp wings divergent at maturity, lateral wings ca. 2 × broader than dorsal wings (subtribe Angelicineae).		(54)
+	Lateral mericarp wings adnate or closely appressed at maturity, lateral wings less than 2 × broader than the dorsal wings.		(61)
54 (53)	Fruit compressed-globose or ellipsoid, ribs all winged, thickened or corky-thickened, ribs equal or lateral ribs slightly broader than dorsal.		(55)
+	Fruit ovoid to oblong, ribs all winged, slender, not corky-thickened, usually lateral ribs broader than or rarely just equaling dorsal.		(57)
55 (54)	Vittae numerous, almost encircling and adhering to the seed.		79 Archangelica
+	Vittae 1–3 in each furrow, 2–6 on commissure, not adhering to the seed.		(56)
56 (55)	Fruit glabrous.		80 Coelopleurum
+	Fruit densely hirsute and velutinous on the surface.		85 Glehnia
57 (54)	Petals yellowish-green to yellow.		84 Levisticum
+	Petals white, rarely pinkish, purplish or dark purple.		(58)
58 (57)	Outer petals of umbellules radiant, conspicuously enlarged.		81 Czernaevia
+	Outer petals of the umbellule not radiant, equal.		(59)
59 (58)	Calyx teeth conspicuous, triangular or ovate, persistent.		83 Ostericum
+	Calyx teeth minute or obsolete.		(60)
60 (59)	Leaf sheaths usually elongate, tube-like; fruit ribs without vascular bundle.		78 Conioselinum
+	Leaf sheaths usually broadly ovate or sacciform; fruit ribs all with vascular bundles.		82 Angelica
61 (53)	Lateral mericarp wings membranous (subtribe Ferulineae).		(62)
+	Lateral mericarp wings thickened, margin rigid (vascular bundle near margin) (subtribe Tordyliinae).		(69)
62 (61)	Flowers polygamous, bisexual flowers only at the terminal primary-umbel, all the lateral umbels with male flowers; stylopodium base dilated, lobed or undulated-margined.		(63)
+	Flowers often bisexual, male flowers only in the upper lateral umbels; stylopodium base usually undilated, entire.		(66)
63 (62)	Petals white; bracteoles usually absent.		86 Arcuatopterus
+	Petals yellow or yellowish-green; bracteoles usually present.		(64)
64 (63)	Flowers pedicellate, umbellules loose, not capitate.		87 Ferula
+	Flowers subsessile; umbellules capitate.		(65)
65 (64)	Fruit densely pubescent, dorsal ribs obscure; vittae 3–5 in each furrow, 10–12 on the commissure.		88 Schumannia
+	Fruit glabrous, dorsal ribs filiform, prominent; vittae 1 in each furrow, 2–4 on the commissure.		89 Soranthus
66 (62)	Flowers yellow.		93 Talassia
+	Flowers white, pinkish or purplish.		(67)
67 (66)	Fruit ribs corky-thickened, dorsal and intermediate ribs rounded, very prominent, lateral ribs broadly winged.		90 Phlojodicarpus
+	Fruit ribs not corky-thickened, dorsal ribs filiform, prominent to slightly prominent, lateral ribs narrowly to broadly winged.		(68)
68 (67)	Calyx teeth obsolete or inconspicuous; bracts present, bracteoles many; lateral ribs of fruit conspicuously winged.		91 Peucedanum
+	Calyx teeth conspicuous, subulate or triangular-subulate; bracts and bracteoles absent or occasionally bracteoles 1–2, caducous; lateral ribs of fruit thickened, slightly winged.		92 Chuanminshen
69 (61)	Petals yellow, equal, apex obtuse-rounded or truncate with an inflexed lobule; fruit vittae long, filiform, extending to fruit base.		94 Pastinaca
+	Petals greenish, whitish or purplish, unequal, usually outer petals markedly enlarged, radiant, apex 2-lobed, with a narrowly inflexed lobule; fruit vittae short, clavate, not extending to fruit base, or long, filiform extending to base.		(70)
70 (69)	Fruit vittae long, filiform, not clavate, usually extending to base, fruit densely pubescent.		(71)
+	Fruit vittae short, clavate, usually not extending to base (very rarely filiform and extending to base), fruit glabrous or glabrescent.		(72)
71 (70)	Outer parts of fruit wings inflated and corky, inner mesocarp layer sclerified.		95 Zosima
+	Outer parts of fruit wings not inflated, inner mesocarp layer not sclerified.		97 Semenovia
72 (70)	Bracts absent or few, caducous, bracteoles linear.		96 Heracleum
+	Bracts and bracteoles numerous, large, lanceolate-ovate, persistent in fruit.		98 Tordyliopsis
73 (8)	Fruit oblong or slightly elongate, cylindrical, beaked; druse crystals abundant in parenchyma surrounding carpophore (tribe Scandicineae).		(74)
+	Fruit globose, ovoid to cylindrical, not beaked; druse crystals absent in parenchyma surrounding carpophore.		(82)
74 (73)	Fruit round-ovoid, ovoid to oblong, setulose or bristly, usually in longitudinal rows.		(75)
+	Fruit cylindrical and beaked, glabrous or bristly but not in longitudinal rows.		(76)
75 (74)	Fertile flowers with radiant petals; primary and secondary fruit ribs prominent.		12 Turgenia
+	Fertile flowers without radiant petals; secondary fruit ribs hidden by the dense glochidiate prickles or tubercles.		11 Torilis
76 (74)	Fruit ribs acute, narrowly winged; vittae obscure when mature.		9 Osmorhiza
+	Fruit ribs rounded, unwinged; vittae conspicuous.		(77)
77 (76)	Apex of fruit shortly or long-beaked; vittae small.		(78)
+	Apex of fruit obtuse or acute, not beaked; vittae large.		(79)
78 (77)	Fruit beak shorter than the body.		8 Anthriscus
+	Fruit beak much longer than the body.		14 Scandix
79 (77)	Fruit elongate, cylindrical; vittae 1 in each furrow.		(80)
+	Fruit linear-oblong; vittae 2–4 in each furrow.		(81)
80 (79)	Rootstock narrow conic.		6 Chaerophyllum
+	Rootstock tuber-like, globose		10 Krasnovia
81 (79)	Calyx teeth obsolete; petals white, apex notched.		7 Sphallerocarpus
+	Calyx teeth conspicuous, persistent; petals purple, apex unnotched.		13 Chaerophyllopsis
82 (73)	Fruit globose-ovoid, pericarp hard (tribe Coriandreae).		(83)
+	Fruit cylindrical to ovoid, pericarp not hard (tribe Smyrnieae).		(84)
83 (82)	Plants annual or biennial; cauline leaves heteromorphic; fruit globose.		15 Coriandrum
+	Plants perennial; cauline leaves not heteromorphic; fruit biglobose.		16 Schrenkia
84 (82)	Fruit ribs unwinged; mericarp rounded in cross section or near pentagonal.		(85)
+	Fruit ribs winged (or unwinged and corky-thickened); mericarp pentagonal in cross section or slightly flattened dorsally.		(95)
85 (84)	Umbels sessile, appearing simple; petals plane, apex acute, slightly incurved.		17 Oreomyrrhis
+	Umbels pedunculate, obviously compound; petal apex narrowly inflexed.		(86)
86 (85)	Primary and secondary fruit ribs conspicuous.		22 Chamaesium
+	Primary fruit ribs conspicuous, secondary ribs obscure.		(87)
87 (86)	Seed face deeply concave or sulcate.		(88)
+	Seed face plane or slightly concave, never sulcate.		(91)
88 (87)	Fruit ribs faint, furrows obscure; vittae numerous.		21 Changium
+	Fruit ribs filiform, prominent, furrow conspicuous; vittae 1–3 in each furrow.		(89)
89 (88)	Rootstock tuber-like; ultimate leaf segments narrowly linear.		33 Scaligeria
+	Rootstock not tuber-like; ultimate leaf segments oblong to broadly ovate.		(90)
90 (89)	Fruit vittae 1 in each furrow, 2 on commissure.		26 Cyclorhiza
+	Fruit vittae 3–5 in each furrow, 6 on commissure.		25 Vicatia
91 (87)	Fruit narrowly long-ovate, tapering toward apex, base not cordate.		19 Meeboldia
+	Fruit ovoid-globose or long-ellipsoid, apex rounded, base usually cordate.		(92)
92 (91)	Fruit surface usually tuberculate.		30 Trachydium
+	Fruit glabrous, not tuberculate.		(93)
93 (92)	Petal midvein inconspicuous; stylopodium depressed.		20 Tongoloa
+	Petal midvein conspicuous; stylopodium conic.		(94)
94 (93)	Leaves 2-ternate-pinnate; ultimate segments broadly ovate-rhombic; petals dark purple.		29 Melanosciadium
+	Leaves 1–2-pinnate, rarely undivided, ultimate segments oblanceolate, obovate or long-ovate; petals white, yellow or purple.		18 Physospermopsis
95 (84)	Fruit ribs corky-thickened, winged or unwinged.		32 Prangos
+	Fruit ribs thinly winged, not corky.		(96)
96 (95)	Bracts and bracteoles few to many, small, undivided.		(97)
+	Bracts and bracteoles well developed, membranous-margined, usually pinnate or apex 3-lobed.		(98)
97 (96)	Fruit ribs sinuate-winged; vittae numerous, encircling seed.		31 Conium
+	Fruit ribs plane-winged; vittae 3–4 in each furrow, 4–6 on commissure.		27 Notopterygium
98 (96)	Petals yellow, apex not narrow and inflexed; dorsal ribs filiform, lateral ribs narrow-winged.		28 Sinolimprichtia
+	Petals white or pinkish, apex narrow, inflexed; fruit ribs usually undulate, cristate or semi-winged.		(99)
99 (98)	Bracteoles herbaceous, often falling in fruit; umbellules not densely crowded (pedicels conspicuous).		23 Pleurospermum
+	Bracteoles stiff, papery, persistent in fruit; umbellules densely crowded (pedicels very short).		24 Pleurospermopsis