Corymbia citriodora
lemon-scented gum
There comes a time in a man’s life when he meets the lemon-scented gum, and his entire conception of eucalypts is overturned. For those of us in Northern California, such a moment once occurred only on visits to Santa Barbara or other warmer, southern parts of the state – the species is subtropical and resents our occasional freezes – but local specimens have now grown to considerable size and can be appreciated close to home.
A slender, smooth, pale trunk soars upward; no enormous, shaggy, shedding behemoth of a blue gum here. Mottled patches of dusty pink and silver-gray bark delicately crack off in summer to expose buff and rich cream beneath. Look up, and high atop this gleaming stem the airy canopy waves, the sun brilliant on the bleached-looking upper limbs. Your phone will leap into your hand; its camera can easily capture the entire crown. Thus far, it almost reads as a palm, or a slender birch – not a eucalypt. But now is when things truly shift. Pick up even a dried leaf off the ground, crush it, and sniff – the lemon scent, nearly pure citronellal, is entirely unexpected. Yes, it’s the compound used in germicides and mosquito repellents, but from the leaf the fragrance is complex, fruity, and utterly devoid of medicinal harshness.
My friend Drew first met this tree by its scent: apprenticing as a young gardener in San Diego, he was unwinding in a friend’s backyard hot tub one night when leaves drifted down into the water and released their signature aroma. Others may catch the fragrance simply by walking over the fallen foliage. Juvenile leaves can sometimes be found near ground level; the projections on their undersides will scent your fingers with lemon oil if you lightly brush against them.
The most centrally located specimens on campus are sequestered between the Durand and McCullough buildings, three tall trees alongside two others sprouting from stumps. An old southern mahogany (Eucalyptus botryoides) looms in the back. A 1967 landscaping plan called for a group of E. robusta here; perhaps these were substitutes. A handsome pair in the outer northwest Quad, visible from the Inner Quad, was removed in 2015 during relandscaping.
In colder sites on campus, trees well over 30 feet have succumbed to a freeze, our last one now some 35 years behind us. In the 2010s, mass plantings of lemon-scented gums took off, with three dozen in closely-spaced plantations on the Campus Drive side of the northeast buildings of Knight Management Center (2011), almost 30 surrounding the Miller and Lieberman Houses in the Kennedy Graduate Residences (2014), and a couple of dozen in a row along Fremont Road at the Central Energy Facility. Also see a pair in front of Schwab Residential Center, near McDonald Hall.
A local champion for girth stands against the right end of 410 Sheridan Avenue in Palo Alto, planted in 1977 when the building went up. Run your hand along the trunk’s evenly rippled musculature. Three more grow nearby, next to the creek in the parking lot at 340 Portage Avenue, their future uncertain amid planned development. Aficionados of the species should visit the splendid median planting in the two blocks of East San Carlos Street just west of San Jose State University. Cleverly interspersed among them is the very similar-looking spotted gum (C. maculata), with slightly broader leaves and none of the lemon scent.
About this Entry: Authored Jul 2025 by Sairus Patel.
