1	Subshrubs	2
1	Vines	6
2	"Leaf lamina trinerved at base"	"Marsdenia trinervis"
2	"Leaf lamina not trinerved at base"	3
3	"Leaf lamina linear"	"Marsdenia angustata"
3	"Leaf lamina lanceolate, elliptic, elliptic-ovate or ovate"	4
4	"Staminal corona absent"	"Marsdenia brevifolia"
4	"Staminal corona prominent, comprising 5 lobes adnate to staminal column"	5
5	"Leaf lamina with venation prominent below; colleters absent; corolla lobes 5–6 mm long"	"Marsdenia graniticola"
5	"Leaf lamina with venation obscure below; colleters 1 or 2; corolla lobes 1.5–4 mm long"	"Marsdenia suaveolens"
6	"Corolline corona present, comprising either 5 ridges at corolla lobe sinuses that sometimes terminate in small apical lobes, or 5 rounded lobes at top of corolla tube"	7
6	"Corolline corona absent"	21
7	"Flowers more than 15 mm diam.; corolla lobes more than 6.5 mm long"	"Marsdenia araujacea"
7	"Flowers less than 15 mm diam.; corolla lobes less than 6.5 mm long"	8
8	"Corolla rotate"	"Marsdenia longiloba"
8	"Corolla campanulate, shallowly campanulate, urceolate or salverform-urceolate"	9
9	"Corolline corona not terminating in apical lobes at top of corolla tube"	10
9	"Corolline corona terminating in apical lobes at top of corolla tube"	16
10	"Corolla salverform-urceolate"	"Marsdenia pumila"
10	"Corolla campanulate"	11
11	"Corolla lobes more than 3.5 mm long"	12
11	"Corolla lobes less than 3.5 mm long"	13
12	"Leaf petiole 20–35 mm long; staminal corona lobes oblong-rectangular, longer than staminal column"	"Marsdenia glandulifera"
12	"Leaf petiole 10–20 mm long; staminal corona lobes subulate, shorter than staminal column"	"Marsdenia rostrata"
13	"Staminal corona lobes peltate"	"Marsdenia viridiflora"
13	"Staminal corona lobes adnate at base"	14
14	"Staminal corona lobes longer than staminal column"	"Marsdenia cymulosa"
14	"Staminal corona lobes shorter than staminal column"	15
15	"Leaf lamina with sparse to dense trichomes below; colleters 5–9"	"Marsdenia pleiadenia"
15	"Leaf lamina glabrous below; colleters 2"	"Marsdenia fraseri"
16	"Indumentum on foliage ginger or yellow"	17
16	"Indumentum on foliage clear to pale yellow"	20
17	"Corolline corona lobes at top of corolla tube prominent and incurved over staminal column"	18
17	"Corolline corona lobes at top of corolla tube small and not incurved over staminal column"	19
18	"Leaf lamina lanceolate"	"Marsdenia muelleri"
18	"Leaf lamina elliptic to ovate"	"Marsdenia straminea"
19	"Corolla tube longer than broad; corolla lobes internally papillose; anther appendages truncate"	"Marsdenia longipedicellata"
19	"Corolla tube as long as broad; corolla lobes internally with longitudinal central band of sparse trichomes; anther appendages obtuse to triangular"	"Marsdenia suborbicularis"
20	"Flowers 3–5 mm long; pollinia 0.12–0.17 mm long; follicles fusiform-ovoid"	"Marsdenia geminata"
20	"Flowers 2–3 mm long; pollinia 0.17–0.22 mm long; follicles fusiform"	"Marsdenia tricholepis"
21	"Leaf lamina with obscure venation below"	22
21	"Leaf lamina with prominent venation below"	25
22	"Leaf lamina linear to lanceolate; staminal corona lobes peltate"	23
22	"Leaf lamina elliptic-ovate or narrowly oblong to oblong; staminal corona lobes adnate at base"	24
23	"Corolla shallowly campanulate; tube 2.6–3 mm long"	"Marsdenia coronata"
23	"Corolla urceolate; tube 4–6 mm long"	"Marsdenia australis"
24	"Staminal corona lobes shorter than staminal column"	"Marsdenia flavescens"
24	"Staminal corona lobes longer than staminal column"	"Marsdenia connivens"
25	"Corolla lobes more than 5 mm long"	26
25	"Corolla lobes less than 5 mm long"	28
26	"Corolla lobes linear-lanceolate; staminal corona lobes with a basal fleshy wing"	"Marsdenia liisae"
26	"Corolla lobes lanceolate; staminal corona lobes without a basal fleshy wing"	27
27	"Corolla campanulate, cream; lobes c. 6 mm long"	"Marsdenia paludicola"
27	"Corolla rotate, red, red-purple or pale pink-cream; lobes 8–14 mm long"	"Marsdenia hemiptera"
28	"Corolla lobes less than 1.5 mm long"	29
28	"Corolla lobes more than 1.5 mm long"	30
29	"Leaf lamina elliptic-oblong to obovate; staminal corona lobes cupular, entire"	"Marsdenia micradenia"
29	"Leaf lamina lanceolate to lanceolate-ovate; staminal corona lobes ovate-oblong, bilobed"	"Marsdenia brevis"
30	"Corolla campanulate"	31
30	"Corolla urceolate"	32
31	"Corolla orange, maroon, brown or green; lobes elliptic-ovate; staminal corona lobes linear"	"Marsdenia velutina"
31	"Corolla white; lobes ovate; staminal corona lobes acute-oblong"	"Marsdenia lloydii"
32	"Leaf lamina glabrous below; staminal corona lobes bilobed, c. 0.8 mm wide"	"Marsdenia rara"
32	"Leaf lamina with sparse to dense trichomes below; staminal corona lobes entire, 1–1.1 mm wide"	"Marsdenia microlepis"