| 1. Flower long-cylindric; umbel open; perianth red and green |
| D. ida-maia |
| 1' Flower bell-shaped to salverform; umbel dense; perianth not red and green |
| |
| 2. Inflorescence weak, twining; perianth pink; stamen-like staminodes alternate fertile stamens |
| D. volubile |
| 2' Inflorescence self-supporting; perianth blue, purple, or white; staminodes 0 |
| |
| 3. Fertile stamens 6 (3 smaller); perianth tube not narrowed above ovary |
| D. capitatum |
| 4. Bracts generally dark purple; flowers generally > 6; pedicels generally < bracts |
| subsp. capitatum |
| 4' Bracts whitish or streaked purple; flowers 25; pedicels > bracts |
| subsp. pauciflorum |
| 3' Fertile stamens 3, equal; perianth tube narrowed above ovary |
| |
| 5. Inflorescence a dense raceme; anther appendages deeply notched |
| D. congestum |
| 5' Inflorescence an umbel; anther appendages truncate or rounded |
| D. multiflorum
|