1	Inflorescence an axillary raceme; plants hermaphroditic.		(2)
+	Inflorescence a solitary flower or sessile cluster of flowers; plants dioecious (hermaphroditic in A. setaceus).		(3)
2 (1)	Spines 15--20 mm on main stems and 5--10 mm on branches		1 Asparagus racemosus
+	Spines 3--5 mm on main stems and indistinct on branches		2 Asparagus densiflorus
3 (1)	Cladodes flat with a distinct midvein or 3-winged.		(4)
+	Cladodes subterete, sometimes slightly flattened, but without clear midvein.		(13)
4 (3)	Stems without sharp spines.		(5)
+	Stems with sharp spines.		(9)
5 (4)	Plants ± climbing; branches sparsely cartilaginous denticulate		12 Asparagus subscandens
+	Plants erect; branches not cartilaginous denticulate.		(6)
6 (5)	Cladodes 3-winged basally; stamens equal, filaments free		7 Asparagus schoberioides
+	Cladodes flat; stamens unequal, filaments adnate to perianth segments for ca. 1/2 their length.		(7)
7 (6)	Pedicels 10--20 mm		4 Asparagus filicinus
+	Pedicels 1--6 mm.		(8)
8 (7)	Cladodes (1 or)2 or 3 per fascicle, 5--12 × (1--)2--3 mm		5 Asparagus lycopodineus
+	Cladodes 5--10 per fascicle, 3--4 × ca. 0.5 mm		6 Asparagus yanbianensis
9 (4)	Male flowers subglobose, 1--1.5 mm		13 Asparagus yanyuanensis
+	Male flowers subcampanulate, 1.5--5 mm.		(10)
10 (9)	Branches and branchlets generally without sharp spines; flowers developing after cladodes.		(11)
+	Branches and branchlets with woody, sharp spines; flowers developing before or with cladodes.		(12)
11 (10)	Cladodes usually 3 per fascicle; filaments free		8 Asparagus cochinchinensis
+	Cladodes 6--9 per fascicle; filaments adnate to perianth segments for ca. 1/2 their length		9 Asparagus taliensis
12 (10)	Cladodes 2--5(--7) per fascicle; stems not striate-ridged; spines on branches shorter than or equaling pedicels		10 Asparagus munitus
+	Cladodes (3--)6--14 per fascicle; stems distinctly striate-ridged; spines on branches longer than pedicels		11 Asparagus myriacanthus
13 (3)	Plants hermaphroditic; cladodes 10--13 per fascicle, filiform, 4--5 mm; secondary branches and cladodes arranged in 1 plane, frondlike		3 Asparagus setaceus
+	Plants dioecious (but flowers sometimes with aborted stamens or pistil); cladodes 1--10(--25) per fascicle.		(14)
14 (13)	Stems with sharp spines 2--3 mm.		(15)
+	Stems and branches unarmed or, if spiny, spines very short, not sharp, and appressed to branches.		(23)
15 (14)	Branches and cladodes ± cartilaginous denticulate.		(16)
+	Branches and cladodes generally not cartilaginous denticulate.		(19)
16 (15)	Plants climbing; roots tuberous, 7--15 mm thick, fleshy		21 Asparagus brachyphyllus
+	Plants erect or suberect; roots sometimes with swollen, tuberous part near tip, 2--4 mm thick, rather slender.		(17)
17 (16)	Plants dwarf subshrubs; branches with woody, sharp spines 2--4 mm; pedicels ca. 1 mm; roots with tuberous part		30 Asparagus kansuensis
+	Plants tall herbs; branches without pungent spines; pedicels 7--15 mm; roots without tuberous part.		(18)
18 (17)	Branches strongly reflexed basally and ascending distally; pedicels 1.2--1.6 cm		25 Asparagus trichophyllus
+	Branches not as above; pedicels 0.6--1.3 cm		24 Asparagus longiflorus
19 (15)	Male flowers 2--4 mm; branches spiny.		(20)
+	Male flowers 6--9 mm; branches unarmed.		(21)
20 (19)	Plants suberect; stem indistinctly striate; perianth of male flowers purplish red, subcampanulate, 3--4 mm in diam.; filaments adnate to perianth segments for ca. 1/4 their length		23 Asparagus tibeticus
+	Plants climbing; stem not striate; perianth of male flowers greenish white, subglobose, 2--2.5 mm in diam.; filaments free		29 Asparagus acicularis
21 (19)	Pedicels (1--)1.5--2 cm; perianth yellowish green		26 Asparagus oligoclonos
+	Pedicels 0.5--1.3 cm; perianth purplish.		(22)
22 (21)	Plants suberect; stem cartilaginous denticulate distally; spines straight; pedicels 6--13 mm		24 Asparagus longiflorus
+	Plants climbing or nearly so; stem not cartilaginous denticulate; spines curved; pedicels ca. 5 mm		22 Asparagus sichuanicus
23 (14)	Plants climbing.		(24)
+	Plants erect.		(26)
24 (23)	Pedicels 6--25 mm; branches not cartilaginous denticulate		20 Asparagus breslerianus
+	Pedicels 2--6 mm; branches usually cartilaginous denticulate.		(25)
25 (24)	Roots tuberous, 7--15 mm thick, fleshy		21 Asparagus brachyphyllus
+	Roots not tuberous, 2--5 mm thick		16 Asparagus trichoclados
26 (23)	Pedicels more than 1 cm.		(27)
+	Pedicels less than 1 cm.		(31)
27 (26)	Branchlets ± cartilaginous denticulate.		(28)
+	Branchlets not cartilaginous denticulate.		(29)
28 (27)	Branches strongly reflexed basally and ascending distally; pedicels 1.2--1.6 cm		25 Asparagus trichophyllus
+	Branches not as above; pedicels 0.6--1.3 cm		24 Asparagus longiflorus
29 (27)	Male flowers ca. 3 mm; filaments free; stem striate-ridged distally; cladodes slightly tetragonous or sometimes irregularly trigonous		14 Asparagus mairei
+	Male flowers 5--9 mm; filaments adnate to perianth segments for 1/2--3/4 their length; stem not or minutely striate; cladodes indistinctly grooved or angled.		(30)
30 (29)	Stems and branches soft, usually ± pendulous apically; male flowers 5--6 mm; anthers 1--1.5 mm		27 Asparagus officinalis
+	Stems and branches rather rigid; male flowers 7--9 mm; anthers ca. 2 mm		26 Asparagus oligoclonos
31 (26)	Young branches cartilaginous denticulate.		(32)
+	Young branches not cartilaginous denticulate.		(35)
32 (31)	Pedicels usually more than 6 mm		24 Asparagus longiflorus
+	Pedicels 3--5 mm.		(33)
33 (32)	Roots with tubers; stem and branches densely cartilaginous denticulate; male flowers ca. 2 mm		15 Asparagus meioclados
+	Roots without tubers; stem and branches not or only slightly cartilaginous denticulate; male flowers more than 3 mm.		(34)
34 (33)	Plants dwarf subshrubs; stems strongly zigzagged toward apex, rigid; cladodes rigid, spinescent		18 Asparagus gobicus
+	Plants tall herbs; stems straight or slightly flexuous; cladodes rather soft, never spinescent		17 Asparagus dauricus
35 (31)	Pedicels more than 8 mm.		(36)
+	Pedicels 2--6 mm.		(37)
36 (35)	Male flowers ca. 3 mm; filaments free; stem striate-ridged distally		14 Asparagus mairei
+	Male flowers 5--6 mm; filaments adnate to perianth segments for ca. 1/2 their length; stem not striate-ridged		27 Asparagus officinalis
37 (35)	Stems with cladodes (except near base), usually covered with stripelike remains of whitish, hyaline periderm when old		28 Asparagus neglectus
+	Stems with cladodes only near apex, without stripelike remains of periderm when old.		(38)
38 (37)	Plants with creeping, stolonlike rhizomes to 2 mm thick; stems usually simple; cladodes in fascicles of 5--7, falcate		31 Asparagus przewalskyi
+	Plants with thick, abbreviated rhizomes 4--20 mm thick; stems always branched; cladodes in fascicles of 1--6, usually straight.		(39)
39 (38)	Roots slender, ca. 2 mm thick; cladodes usually spreading upward at an acute angle		17 Asparagus dauricus
+	Roots rather thick, 4--5 mm thick; cladodes spreading downward at an obtuse angle		19 Asparagus angulofractus