Leaves alternate, simple or pinnate, generally attenuate at the base, glabrous to hairy.
Inflorescences cymose. Flowers male, female or bisexual. Sepals 3–7, usually 4, free, sometimes persistent. Petals absent. Stamens 6–16, usually 8–10, in female flowers absent or rudimentary. Disc small. Ovary 2–6-carpellate, glabrous or sometimes pubescent, usually reflected in capsule, usually sticky; in male flowers rudimentary or absent.
Capsule 2–4-angled and usually prominently 2–4-winged, membranous or leathery, dehiscence usually by valves breaking away from the septa; aril mostly absent; testa covered with hyaline membrane.
| | Key to the species | |
| 1 | Leaves simple or pinnatifid with lobes shorter than breadth of lamina (Dodonaea lobulata) | 2 |
| Leaves compound, the leaflets longer than the breadth of the rachis | 23 |
| 2 | Capsule winged, the wings extending from capsule base to apex, usually prominent and more than 2 mm wide (less than 1 mm in Dodonaea procumbens) | 3 |
| Capsule globose, not prominently winged, the appendage at capsule apex only, usually lobe-like or horn-like or sometimes absent, or rarely a wing to 1.5 mm wide
Back to 1 | 20 |
| 3 | Capsule wings rounded, with their longest axis parallel to capsule axis, more or less equal in breadth from base to apex | 4 |
| Capsule wings rounded or pointed, oblique with their longest axis perpendicular to the capsule axis, larger at capsule apex than at base
Back to 2 | 17 |
| 4 | Leaves more or less filiform, cylindrical or narrow-linear, less than 2 mm wide, terete or 4-ribbed or channelled above or flat, margins entire | 5 |
| Leaves never more or less filiform or cylindrical, flat, margins entire to regularly toothed or lobed, if linear then more than 2 mm wide and sinuate
Back to 3 | 6 |
| 5 | Branchlets finely pubescent; leaves falcate, not rigid, 2.5–4 cm long, rarely to 5 cm | Dodonaea falcata |
| Branchlets glabrous; leaves straight, usually erect, often rigid, 4–10.5 cm long, or rarely as short as 3 cm
Back to 4 | Dodonaea viscosa |
| 6 | Leaves sticky, shiny and glabrous, or pubescent | 7 |
| Leaves not sticky, dull, glabrous
Back to 4 | 14 |
| 7 | Leaves more than 10 mm wide | 8 |
| Leaves less than 10 mm wide
Back to 6 | 9 |
| 8 | Capsule greatly inflated, not readily dehiscent, the wings 1.5–4 mm wide | Dodonaea petiolaris |
| Capsule not inflated, dehiscent, the wings more than 4 mm wide
Back to 7 | Dodonaea viscosa |
| 9 | Leaves usually less than 2.5 mm wide, linear, pinnatifid or irregularly 2–12-lobed | Dodonaea lobulata |
| Leaves usually more than 2.5 mm wide, oblong, angular-obovate to obovate, entire or irregularly toothed or lobed at apex
Back to 7 | 10 |
| 10 | Leaves 5–9 mm wide | 11 |
| Leaves 2–5 mm wide, or rarely to 8 mm wide
Back to 9 | 12 |
| 11 | Erect shrub; capsules 11–28 mm wide, wings more than 2 mm wide | Dodonaea viscosa |
| Prostrate shrub; capsules 8–10.5 mm wide, wings 0.5 mm wide
Back to 10 | Dodonaea procumbens |
| 12 | Leaves linear to oblong, decurrent at base; sepals not persistent | Dodonaea camfieldii |
| Leaves angular-obovate to obovate, not decurrent at base; sepals persistent
Back to 10 | 13 |
| 13 | Leaves hirsute, petiolate, 3–6 mm long; capsule hirsute; inflorescences axillary | Dodonaea hirsuta |
| Leaves glabrous, sessile, 5–18 mm long; capsule glabrous; inflorescences terminal
Back to 12 | Dodonaea peduncularis |
| 14 | Leaves sessile, 0.8–3.5 cm long, apex obtuse or rounded, rarely mucronate | Dodonaea bursariifolia |
| Leaves petiolate, rarely subsessile, lamina 3–12 cm long, apex acuminate to obtuse
Back to 6 | 15 |
| 15 | Leaves irregularly toothed, 6–12 mm wide; inflorescences a 3–6-flowered cyme, pedicels 2–2.5 mm long | Dodonaea serratifolia |
| Leaves entire or sinuate, 10–47 mm wide; inflorescences a terminal panicle, pedicels more than 4 mm long
Back to 14 | 16 |
| 16 | Capsule mostly 16–19 mm long, wing coriaceous; leaves concolorous | Dodonaea lanceolata |
| Capsule mostly 11–14 mm long. wing membranous; leaves discolorous
Back to 15 | Dodonaea triquetra |
| 17 | Leaves elliptic, 14–27 mm wide, with length:breadth ratio of less than 5:1 | Dodonaea rhombifolia |
| Leaves usually linear, lanceolate or oblanceolate, rarely narrow-elliptic, 1–13 mm wide, with length:breadth ratio of more than 5:1
Back to 3 | 18 |
| 18 | Leaves linear, rigid, 1–2.5 mm wide | Dodonaea stenophylla |
| Leaves oblanceolate, linear or narrow-elliptic, 2–13 mm wide
Back to 17 | 19 |
| 19 | All leaves simple, 5–13 mm wide; capsule 3–4-winged | Dodonaea truncatiales |
| Leaves simple or irregularly pinnate with 1–10 leaflets, 2–5 mm wide; capsule 4-winged
Back to 18 | Dodonaea heteromorpha |
| 20 | Petiole 7.5–14 mm long; capsule greatly inflated more than 15 long, more than 11.5 mm wide | Dodonaea petiolaris |
| Leaves sessile or petiole less than 3 mm long; capsule not inflated, less than 13 mm long, less than 11.5 mm wide
Back to 2 | 21 |
| 21 | Leaves with apex obtuse or rounded, entire, glabrous | Dodonaea bursariifolia |
| Leaves with apex acute, usually regularly toothed or sometimes 3-toothed, pubescent
Back to 20 | 22 |
| 22 | Leaves 6–30 mm wide; capsule 6–9 mm long, usually sparsely pubescent; appendages usually present, lobe-like, 1–2 mm wide | Dodonaea triangularis |
| Leaves 4–8.5 mm wide; capsule 11–13 mm long, glabrous; wings 0.5 mm wide
Back to 21 | Dodonaea procumbens |
| 23 | Capsule lacking wings | Dodonaea macrossanii |
| Capsule prominently winged
Back to 1 | 24 |
| 24 | Capsule wings rounded, with their longest axis parallel to the capsule axis, more or less equal in breadth from base to apex; leaflets usually less than 12 mm long | 25 |
| Capsule wings rounded or pointed, oblique, their longest axis perpendicular to the capsule axis, larger at capsule apex than the base; leaflets usually more than 12 mm long
Back to 23 | 30 |
| 25 | Leaflets linear, less than 2 mm wide | Dodonaea sinuolata |
| Leaflets various shapes, mostly narrow- to broad-obovate, never linear or linear-oblanceolate, more than 2 mm wide
Back to 24 | 26 |
| 26 | Leaflets with sunken glands near margin on upper surface | 27 |
| Leaflets without sunken surface glands
Back to 25 | 28 |
| 27 | Lateral leaflets less than 15 | Dodonaea boroniifolia |
| Lateral leaflets more than 15
Back to 26 | Dodonaea multijuga |
| 28 | Petioles at least 6 mm long | Dodonaea sinuolata |
| Petioles less than 6 mm long
Back to 26 | 29 |
| 29 | Leaves densely hirsute; lateral leaflets more than 8; sepals persistent in fruit | Dodonaea pinnata |
| Leaves pubescent; lateral leaflets less than 8; sepals not persistent
Back to 28 | Dodonaea microzyga |
| 30 | Leaves usually simple, sometimes irregularly pinnate with 1–10 irregularly spaced leaflets | Dodonaea heteromorpha |
| Leaves imparipinnate with 6–15 pairs of leaflets
Back to 24 | Dodonaea megazyga |
