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| 1 Calyx conspicuously 5-winged (each calyx segment strongly keel-winged) |
| 1 Calyx not winged. |
| ..2 Flowers < 2 mm long. |
| ....3 Leaves elliptic, cuneate at the base; calyx lobes even, all of the sinuses reaching nearly to the base of the calyx |
| ....3 Leaves orbicular, rounded at the base; calyx lobes uneven, 3 of the sinuses extending about halfway to the base of the calyx, the lowermost sinus extending to the base |
| ..2 Flowers > 4 mm long. |
| ......4 Fertile stamens 4; calyx lobes connate at anthesis for > ½ their length, later separating |
| ......4 Fertile stamens 2 (with 2 staminodia without anthers, or with rudimentary anthers); calyx lobes separate, or connate at base for < ¼ the length of the calyx. |
| ........5 Capsule lanceoloid, > 8× as long as its diameter; calyx lobes connate at the base ca. ¼ the length of the calyx |
| ........5 Capsule ovoid to ellipsoid, < 5× as long as its diameter; calyx lobes connate at the base ca. 1/8 the length of the calyx |