Leaves alternate, variable in size, margins entire; sometimes aromatic when crushed; sessile to shortly petiolate.
Fruits thin-walled and usually deciduous, but some species have fruits with a somewhat succulent hypanthium and are semi-persistent. Seeds with a reticulate surface and several vertical rows of loose cells that are sometimes expanded into a narrow wing (e.g. in G. laevigatum). Unfertilised ovules (“chaff”) are readily distinguishable from fertile seeds.
| | Key to the species | |
| 1 | Fruit loculi usually >5; many seeds winged | 2 |
| Fruit loculi 5 or less; seeds not winged | 3 |
| 2 | Leaves light yellowish green, usually 10–20 mm long and 3–5 mm wide, obtuse, acute or acuminate; fruit usually 4–7-locular | Gaudium coriaceum |
| Leaves usually grey-green, 15–30 mm long, 5–8 mm wide, and broadly obtuse; fruit usually 6–11-locular
Back to 1 | Gaudium laevigatum |
| 3 | Sepals very short-triangular, c. 0.5 mm long; leaves 5–10 mm long and 1–3 mm wide with the apex tending to recurve | Gaudium myrsinoides |
| Sepals, if triangular, ≥1 mm long; leaves various
Back to 1 | 4 |
| 4 | Fruit wall succulent (coarsely wrinkled when dry); hypanthium silky with the upper part spreading widely and often glabrous; leaves mostly 5–10 mm long, 1.5–2.5 mm wide and thick | Gaudium semibaccatum |
| Fruit wall not succulent; hypanthium variously hairy or glabrous; leaves various
Back to 3 | 5 |
| 5 | Fruit with the placenta low and the valves extended upward; leaves to c. 8 mm long, thick, obtuse and petiolate | Gaudium parvifolium |
| Fruit not as above; leaves if <10 mm not thick, obtuse and petiolate
Back to 4 | 6 |
| 6 | Bark in many flaky layers even on leafy branches | 7 |
| Bark compact, fibrous, smooth or ultimately flaking but not in many flaky layers
Back to 5 | 8 |
| 7 | Hypanthium densely pubescent with spreading or short hairs (variable according to the population), rarely glabrous, upper part of the hypanthium not incurved; leaves mostly 10–20 mm long, 1–6 mm wide (breadth often uniform within the population) | Gaudium trinervium |
| Hypanthium glabrous or densely silky at base, the upper part incurved over the edge of the fruit; leaves usually 15–25 mm long and 3–7 mm wide
Back to 6 | Gaudium subglabratum |
| 8 | Hypanthium mostly glabrous but sometimes silky at the base; filaments often with spreading hairs | 9 |
| Hypanthium variously hairy, sometimes with the upper part glabrescent; filaments glabrous
Back to 6 | 10 |
| 9 | Hypanthium turgid; leaves mostly elliptic, 10–25 mm long, 2–4 mm wide and petiolate | Gaudium polyanthum |
| Hypanthium thin; leaves narrow-elliptic to oblanceolate, 10–15 mm long and 1–2 mm wide, sessile
Back to 8 | Gaudium deanei |
| 10 | Apex of leaves with a conspicuous pungent point, the leaves subtending the flowering shoots infolded or incurved, and reflexed | 11 |
| Apex of leaves obtuse or acute but if somewhat pointed not conspicuously so and with the leaves subtending the flowering shoots not infolded, incurved and reflexed
Back to 8 | 12 |
| 11 | Sepals somewhat acute and triangular; fruit usually 3-locular | Gaudium divaricatum |
| Sepals obtuse, oblong or semicircular; fruit mostly 4-locular
Back to 10 | Gaudium microcarpum |
| 12 | Leaf bud of flowering shoots developing prematurely so that flowers are found at the base of shoots or even branched shoots, the branching at c. 60° | 13 |
| Leaf bud of flowering shoots developing with or shortly after the flowers; the branching <40°
Back to 10 | 14 |
| 13 | Pedicels >5 mm long; leaves silky only on base and margins; in the Lithgow area, CT | Gaudium blakelyi |
| Pedicels c. 1 mm long; leaves usually silvery silky on both surfaces; confined to the Scabby Ra., ST
Back to 12 | Gaudium namadgiense |
| 14 | Fruit 3-locular, style base scarcely inset, pedicel c. 1 mm long; leaves <10 mm long, 1–3 mm wide, apex usually acute to acuminate | Gaudium multicaule |
| Fruit usually 5-locular, style inset, pedicel 2–10 mm long; leaves mostly >10 mm long, usually 2–5 mm wide, apex obtuse to short-acuminate
Back to 12 | Gaudium brevipes |
