Key to identify the Clematis Cultivar Groups

1 flower upright = 2
1 flower nodding or drooping = 19

flower upright
2 from 1
2 peduncle without bracts = Montana Group
2 peduncle of axillary flowers with bracts = 3
3 from 2
3 flower unisexual or flower with tepal-like staminodes and/or pistillodes = 4
3 flower bisexual = 9

4 from 3
4 flower with tepal-like staminodes and/or pistillodes = 5
4 flower without tepal-like staminodes or pistillodes = 7
5 from 4
5 inflorescence on young shoots with terminal flower first = Patens Group
5 inflorescence on young shoots with flowers from the base upwards = 6
6 from 5
6 flower bud upright = Florida Group
6 flower bud, even if only for a short period, nodding = Viticella Group
7 from 4
7 inflorescence with terminal flower first, tepal colour usually violet, sometimes pink or cream = Heraleifolia Group
7 inflorescence from the base upwards, tepal white or green = 8
8 from 7
8 leaves herbaceous, roots fibrous = Vitalba Group
8 leaves leathery, roots fleshy = Forsteri Group

9 from 3
9 inflorescence on young shoots from the base upwards = 10
9 inflorescence on young shoots with terminal flower first = 15
10 from 9
10 roots fibrous = 11
10 roots fleshy = 12
11 from 10
11 flower bud upright = Vitalba Group
11 flower bud nodding, even if only nodding for a short period = Tangutica Group
12 from 10
12 tepals thick and flower first tulip-shaped = Texensis Group
12 tepals thin and spreading = 13
13 from 12
13 inflorescence many flowered, leaves leathery = Armandii Group
13 flowers solitary or a few flowered dichasial cyme, leaves not leathery = 14
14 from 12
14 flower bud upright = Florida Group
14 flower bud nodding, even if only nodding for a short period = Viticella Group

15 from 9
15 roots fibrous = 16
15 roots fleshy = 17
16 from 15
16 flower first urceolate and/or spreading, tepal colour usually violet, sometimes pink or cream = Heracleifolia Group
16 flower campanulate and/or spreading, tepal colour usually yellow, sometimes cream, stained red-purple or even towards orange = Tangutica Group
17 from 15
17 tepals thick and flower first tulip-shaped = Texensis Group
17 tepals thin and spreading = 18
18 from 17
18 inflorescence many flowered = Flammula Group
18 flower solitary or a 3-flowered dichasial cyme, rarely more = Patens Group

flower nodding or drooping
19 from 1
19 leaf without a petiole = Integrifolia Group
19 leaf with a petiole = 20
20 from 19
20 peduncle always without bracts = Atragene Group
20 peduncle of axillary flowers with bracts = 21
21 from 20
21 flower drooping = 21 
21 flower not drooping = 23
22 from 21
22 flower campanulate = Cirrhosa Group
22 flower urn-shaped = Campanella Group

23 from 21
23 flower unisexual or flower with tepal-like staminodes and/or pistillodes = 24
23 flower bisexual = 26
24 from 23
24 flowers with fertile stamens and/or fertile pistils = 24
24 flowers sterile = Viticella Group
25 from 24
25 inflorescence on young shoots from the base upwards = Forsteri Group
25 inflorescence on young shoots with terminal flower first= Heracleifolia Group

26 from 23
26 roots fibrous = 27
26 roots fleshy = 30
27 from 26
27 inflorescence on young shoots from the base upwards = 28
27 inflorescence on young shoots with terminal flower first = 29
28 from 27
28 flower urn-shaped, at least at the base = Campanella Group
28 flower campanulate to spreading = Tangutica Group
29 from 27
29 flower first urceolate and/or spreading, tepal colour usually violet, sometimes pink or cream = Heracleifolia Group
29 flower campanulate and/or spreading, tepal colour usually yellow, sometimes cream, stained red-purple or even towards orange = Tangutica Group

30 from 26
30 flower urn-shaped = Viorna Group
30 flower campanulate to spreading = 31
31 from 30
31 inflorescence on young shoots with terminal flower first = 32
31 inflorescence on young shoots from the base upwards = Viticella Group / Jackmanii Group
32 from 31
32 climbing plant, tepals almost spreading = Viticella Group / Jackmanii Group
32 plant usually not climbing, flower campanulate or spreading = Diversifolia Group


The Cultivar Groups we use, Clematis nursery J. van Zoest B.V., are partly based on:
Wim Snoeijer (2008) Clematis Cultivar Group Classification with Identifying Key and Diagrams.

For our Cultivar Groups we do not use:
RHS (all copies) RHS Plant Finder.
reason: no Key and no Cultivar Group descriptions.

NAKT (all copies) List of names of Woody Plants / List of names of Perennials.
reason: no Key and no Cultivar Group descriptions.

Magnus Johnson (1997/2001) The Genus Clematis.
reason: Cultivar Groups are not applied.

Grey-Wilson (2000) Clematis. A Gardener's Guide to the Genus.
reason: Cultivar Groups are not applied.

RHS ICRA (2002) Clematis register & supplements.
reason: no Key and 2 levels.

Toomey & Leeds (2010) An Illustrated Encyclopedia of Clematis.
reason: 2 Cultivar Group classifications.