Eucalyptus L’Hér.

2. Eucalyptus L’Hér. View in CoL 1

Trees with persistent or deciduous, smooth or fibrous bark. Leaves dimorphic; juvenile leaves opposite, sessile or shortly petiolate, often glaucous, frequently produced on mature trees in response to wounding; mature leaves alternate, petiolate, pendent, tough, rigid, with a prominent intramarginal vein. Flowers in umbels or solitary, closed in bud by the connate perianth-segments forming a hemispherical or conical operculum which falls off when the flower opens. Fruit a capsule, opening by valves which are described as exserted when they project beyond the rim of the capsule and enclosed when they remain below the rim.

A large genus centred in Australia. Specific identification is based largely on characteristics of the bark, and on operculum- and capsule-shape, although subdivision of the genus is based principally on anther-morphology. The large number of species examined in Australia all have 2« = 22.

The species described below have been planted in Europe (mainly in S.W. Europe and Italy) on a fairly large scale for timber, for shelter, for soil-stabilization, or as an antimalarial measure. Other species occasionally planted include E. amygdalinus Labili. , Nov. Holl. Pl. 2: 14 (1806) ( E. salicifolius auct.), E. cladocalyx F. Mueller , Linnaea 25: 388 (1853), E. gunnii Hooker fil. , London Jour. Bot. {Hooker) 3: 499 (1844), and E. salignus Sm. , Trans. Linn. Soc. London 3: 285 (1797).

Literature: W. F. Blakely, A Key to the Eucalypts, ed. 2. Canberra. 1955. A. R. Penfold & J. L. Willis, The Eucalypts. London and New York. 1961.

1 Flowers solitary; fruit more than 10 mm 9. globulus 1 Flowers in umbels; fruit not more than 10 mm 2 Fruit sessile or subsessile 3 Umbels 3-flowered; peduncles terete 11. viminalis 3 Umbels (3—)5- to 10-flowered; peduncles compressed 4 Leaves more than 18 cm; bark smooth; fruit glaucous 10. maidenii 4 Leaves less than 18 cm; bark fibrous; fruit not glaucous 5 Peduncles 7-10 mm; fruit 7-9 x 7-9 mm, cylindrical 1. botryoides 5 Peduncles 25-35 mm; fruit 13-20x 11-15 mm, campanulate 5. gomphocephalus 2 Fruit distinctly pedicellate 6 Peduncles compressed, angular or strap-shaped 7 Fruit 5-8 mm, ovoid to hemispherical; valves strongly exserted 3. resinifer 7 Fruit 12-15 mm, cylindrical to urceolate; valves enclosed or very slightly exserted 2. robustus 6 Peduncles terete or nearly so 8 Bark smooth, white 9 Peduncles 10-15 mm; fruit 7-8 x 5-6 mm, hemispherical 7. camaldulensis 9 Peduncles 5-12 mm; fruit 6-9x8-10 mm, broadly turbinate 6. tereticornis 8 Bark rough, black or reddish 10 Leaves with inconspicuous veins 4. xtrabutii 10 Leaves with prominent veins 8. rudis