Eucalyptus | Symphyomyrtus | Bisectae | Destitutae | Subulatae | Decurrentes
Bark smooth throughout, grey or grey-brown over creamy-brown to pale coppery to pale orange, decorticating in ribbons which occasionally hang in the upper branches.
Juvenile growth (coppice or field seedlings to 50 cm): not seen.
Adult leaves alternate, petiole 1.5–2.5 cm long; blade lanceolate, (6)7–13(14) cm long, 1–2.3 cm wide, base tapering to petiole, concolorous, glossy, green to dark green, side-veins at an acute or wider angle to midrib, densely reticulate, intramarginal vein parallel to and just within margin, oil glands numerous and mostly intersectional.
Inflorescence axillary unbranched, peduncles 0.5–1.3 cm long, usually pendulous; buds 7, 9 or 11, pedicellate, pedicels 0.4–0.7 cm long. Mature buds 1.2–1.7 cm long, 0.4–0.6 cm wide, with hypanthium urceolate, sometimes ribbed, scar present, operculum beaked to horn-shaped (0.7–1.1 cm long, stamens inflexed, anthers versatile, basifixed, globoid, dehiscing by slits, style long, stigma tapered, locules 3 or 4, the placentae each with 4 vertical ovule rows. Flowers pale yellow to white.
Fruit pedicellate, pedicels 0.3–0.7 cm long, often pendulous, urn-shaped, 0.9–1.1 cm long, 0.6–0.9 cm wide, disc descending, valves 3 or 4, valve tips strongly exserted due to fragile style remnants.
Seeds glossy brown to grey, 1.2–2 mm long, ovoid or flattened-ovoid, rarely pointed at one end, occasionally with shallow longitudinal furrows on otherwise smooth dorsal surface, hilum ventral.
Cultivated seedlings (measured at node 10): cotyledons Y-shaped (bisected); stems square in cross-section and prominently winged due to decurrent leaf bases; leaves opposite, sessile, linear for the first few nodes then ovate to elliptical, dull green to grey-green, 2.2–5 cm long, 1.3–2.5 cm wide, leaf base decurrent on stem.
Flowering has been recorded in December.
A mallee from southern Eyre Peninsula, South Australia, in the Yeelanna, Cummins and Koppio area. The bark is smooth and the adult leaves are glossy, green to dark green.
Eucalyptus peninsularis belongs in Eucalyptus subgenus Symphyomyrtus section Bisectae subsection Destitutae because buds have two opercula, cotyledons are Y-shaped and branchlets lack oil glands in the pith. Within this subsection E. peninsularis is part of a large taxonomic series Subulatae further characterised by globoid basifixed anthers, grey smooth seeds with shallow longitudinal furrows, and fruit with persistent exserted style remnants. Series Subulatae is divided principally into four subseries based on the juvenile leaves, one with spiral, crowded seedling phyllotaxis (subseries Spirales), another with decussate and decurrent seedling leaves (subseries Decurrentes), another with decussate non-decurrent seedling leaves (subseries Decussatae), and a fourth with disjunct, petiolate seedling leaves (subseries Oleaginae).
Eucalyptus peninsularis is part of subseries Decurrentes. Within this subseries it is closest to E. urna and differs by its mallee habit (tree or mallet in E. urna). E. peninsularis is also close to E. flocktoniae and E. neutra and can be easily distinguished from both by its ribbed buds and fruit (both more or less smooth in E. flocktoniae and E. neutra).
Two other species in series Subulatae growing in the vicinity of E. peninsularis are E. socialis subsp. viridans and E. oleosa subsp. oleosa. E. socialis subsp. viridans has decussate but not decurrent seedling leaves and its fruit is not as strongly urceolate as in E. peninsularis. E. oleosa subsp. oleosa has narrow linear to ovate, alternate juvenile leaves, and the fruit is truncate-globose.