Myrtaceae (myrtle family) › Angophora, Corymbia, Eucalyptus

Eucalypt Notes

The Eucalypt Walk: a dozen or so species of eucalypts lined the Campus Drive pathway and median next to Manzanita Field. Almost all were removed due to construction. Sairus, 3 Jun 2015
Rose-colored staminal filaments of Eucalyptus sideroxylon ‘Rosea’. John Rawlings

Eucalypts from Australia are a feature of the campus scene. Hundreds were planted as avenues on campus, dating back to the acquisition of the land by Leland Stanford: Gum Tree Lane, later to be known as Governor’s Avenue, stretched for 1.6 miles with more than 1000 Tasmanian blue gums (Eucalyptus globulus) from San Francisquito Creek to Lake Lagunita and on through the stables to the Red Barn. Two decades later the trees were cut to tall stumps, partly to force regrowth with multiple stems and partly for fuel. That wood was a principal fuel in California does not readily come to mind in these days when gas and electricity are conveniently available for heating and cooking. By the 1950s the unpaved avenue was used as a shady walk and, by nearby residents, as a wood lot. One tree, a short distance south from Santa Teresa Street, had a girth of 26 feet. Governor’s Avenue has been thinned from time to time to make room for road construction and new buildings; for example in January 2003 eight original giants that shaded the Medical Plaza at 1101 Welch Road were removed. The largest had a major diameter of 8 feet. Beneath one of a pair left standing next door at Blake Wilbur Clinic is a granite marker reading as follows:

GOVERNOR’S LANE

This tree lined lane once served as a direct access from the original Stanford home to the Lake Lagunita area. This lane follows a true north/south alignment and provides one of the most significant landscape artifacts on the Stanford Campus. Long since abandoned as a usable route, the Governor’s Lane is in the process of being re-established as a pedestrian, vehicular and visual corridor. Over the next few years, dying Eucalyptus trees will be replaced and a pathway constructed to provide a continuous link as it once stood.

One may wonder who made this commitment.

A curved drive leading upstream along San Francisquito Creek from the Stanford residence (originally the home of George Gordon, d. 1869) used a mix of eucalyptus species. Searsville Road, which ran from the Oval to Sand Hill Road, was planted mainly with E. camaldulensis with some E. viminalis and E. globulus. Until its death in 2002, the very tall E. viminalis at Varian physics, with a girth of 23 feet, was a relic of Searsville Road, as is a blue gum in the parking lot between Ginzton Laboratory and Panama Street. Other eucalypts were planted in the 1890s as a savannah in the Arboretum.

Experience with blue gums over more than 30 years led the Board of Trustees in the early 20th century to plant a triangular area across Galvez Street from the football stadium as an investment. That the trees were planted 6 feet apart indicates that harvesting was intended within a few years, however the crop was never harvested. Consequently, competition for sunlight and moisture, interspersed by occasional drought and severe freezes, made the weakened grove (now quaintly named Toyon Grove) a prime target for longicorn beetles that arrived in 1988, four years after their discovery in Orange County.

These extraordinary beetles can smell a fallen branch, or sawn wood, from a distance, and come promptly to deposit eggs under the bark. On hatching, the legless, eyeless, large-headed larvae cut tunnels through the inner bark, fanning out both up and down from the hatching site in ever-widening tunnels separated by paper-thin partitions. They crawl with their bellies parallel to the bark surface, waving their heads from side to side as they gnaw, cutting an elliptical tunnel; the space behind the larva is left stuffed with compacted, undigested sawdust. When they are ready to pupate, they burrow into the sapwood for protection from grub-seeking birds. If cut wood is removed to a wood-pile for later use as firewood, the larvae will continue feeding for months until beetles emerge, wherever the new site happens to be. If the attack is made on a living tree then kino, a sticky resin, will be exuded to engulf the intruders, if the tree is in good health. If not, it will soon die because the tightly packed and numerous tunnels cut off the flow of sap from the roots. Wasps from Australia have been released in California as a control measure. The Toyon grove was thinned and the trees that were removed were burned or buried; today the grove is still functioning for the purposes to which football fans have become accustomed. Larvae have also been found in wood fallen from coast live oak. A different longhorned beetle caused 700 maples in Brooklyn to be taken down in 1996 and in 2002 two maples were reported as infected five miles away in Central Park.

At the Stanford centenary celebration President Donald Kennedy recognized an historic turning point by burying a longicorn beetle below the 1991 brass plate under the west arch of the Inner Quad, the same location as for the opening ceremony of 1891. This Australian species of longicorn appeared in El Toro, California, possibly from Chile. On a sinister note, the California Department of Forestry reported that “The insect is loose and it’s just a matter of time before it infests every eucalyptus stand we have in California … the bug may be deliberately spread by enthusiasts who would like to rid the California landscape of the ubiquitous eucalyptus.” What with the release of syngaster wasps in 1989 by the University of California, Riverside, and the natural ability of healthy trees to respond with kino, there is room for restrained optimism. As for ridding the state of aliens (see Melaleuca (Paperbark) Notes on xenophobia), pause to learn that of 112 wintering locations of the monarch butterfly in California, three-quarters are in eucalyptus groves!

Longicorn larvae are in abundant supply in infested wood and, although only an inch long, probably are flavorsome when lightly roasted, but they are as nothing compared with the famed witchetty grubs, larvae of other longicorns, as thick as your finger and 4 inches long, that have been an Australian staple for millennia.

Meanwhile, the psyllids have struck again. A few years ago psyllids from Peru devastated our pepper trees, particularly on Stanford Avenue, where many trees were removed. Meanwhile, another psyllid, the lerp insect from Australia, has infested several species of eucalyptus. The tiny insects are found on the leaves, sheltered by a white tent, known as a lerp, about ⅛ inch in diameter. It is hard to believe that the barely visible insect feeding contentedly inside can do so much damage to the foliage as a whole; it evidently releases a bad enzyme while feeding. Wasps that specialize in parasitizing lerp insects have been released and it remains to be seen what the net damage will prove to be. The fallen lerps are sugary and edible, but when they fall on a hard surface they stick to the shoes and make a mess when tramped into the house.

The different eucalyptus species far outnumber the species of oaks and pines, the next most abundant genera on campus. The many eucalypts are conveniently grouped according to the type of bark.

Ironbarks, except when young, have hard, rough, fissured bark, very dark to jet black, that does not drop off. See them around Meyer Green and on Panama Street (E. sideroxylon).

Boxes have rough but fibrous bark, usually light gray. An example is red box E. polyanthemos (whose wood is red, as was well known when trees were cut for use); it is one of three or four species whose foliage is sold by florists as “silver dollar gum,” and flourishes on both sides of Campus Drive East.

Stringybarks have long-fibered bark that was used for cordage, roofing, and the slab walls of early cabins:

Of stringybark slabs were the walls of our hut
From stringybark saplings the rafters were cut
And the roof that long sheltered my brother and me
Was made of the bark of the stringybark tree.

Bloodwoods are a group with rough, tessellated bark that is persistent but drops a few scaly flakes; Corymbia ficifolia (syn. E. ficifolia) for example. The common name refers to veins of resin (kino) resembling congealed blood, but the timber is ranked as durable. According to an 1892 report in the Proceedings of the Linnean Society of New South Wales, aboriginals warmed the kino of the local bloodwood (E. gummifera) to spread on wounds.

Gums, in the restricted sense, have thin smooth bark that peels off in strips, sometimes very long sheets, leaving variegated color patches where the new bark beneath is revealed. The word “gum” refers to the substance sold as kino, a dark resinous substance that contains tannin and is insoluble, as distinct from gums, which are water-soluble carbohydrates. Kino was used for treating dysentery, being lumped in the pharmocopoeia with other dark red resins, under Sanguis Draconis (dragon’s blood).

Kino oozes from wounds in the bark, drowning insects if such happen to be the cause; the pitch from wounded conifers functions for the same purpose. Blue gums (E. globulus), red gums (E. camaldulensis), ribbon gums (E. viminalis), sugar gums (E. cladocalyx), and red-spotted gums (E. mannifera, syn. E. maculosa) are the numerous representatives on campus. The bark types are often distinguishable at a glance but the appearance changes with age and, in the case of gums, with season. Of three gums of the same species growing side by side, one may have a stocking of rough bark, one may have peeled to the ground, and one may be peeling only on the branches and upper trunk. Sometimes boxes and stringybarks look much the same but they feel different. Red-spotted gum not only has a distinctive feel but gives you an urge to help it shed its thin brittle plates.

The term mallee refers to low-growing, bushy species with multiple stems, although you can force one to become a small standard tree by pruning. Occasionally a species that is normally upright produces a sport that seems to have the mallee gene (if there is such) and develops many trunks from ground level.

A single-trunked tree that is cut or frozen off at ground level may develop several strong trunks, but ultimately one will gain dominance, and many years later the plant will be back to a single trunk. Examples of this were seen on Lathrop Drive and Sonoma Terrace with the red-flowering gums after the freeze of 1972. Mallees do not have this apical dominance.

As soon as eucalypts came to the attention of European explorers the great height of several species drew attention. It is now established that the world’s tallest broadleaved trees are eucalypts. A mountain ash (E. regnans) in Tasmania was carefully measured at 321 feet in 1956 and one in Victoria at 374 feet in 1981. Even greater heights were reported in the 19th century for trees that were felled and measured by pacing. The diversity and abundance of accounts in encyclopedias old and new convey the dramatic impression made on early observers. The trees in the great grove on the Berkeley campus, planted in 1877, are 200 feet high. Captain Joseph Aram’s impressive blue gum in San Jose on Schallenberger Road at Old Bayshore Highway was planted in 1856 and is the oldest California specimen of which there is record. At the other end of the size spectrum, there are dozens of denizens of arid areas that never reach 10 feet, and in many cases much less. There is an attractive specimen of E. albida on Stanford land at 3185 Alpine Road that had not reached 3 feet at 35 years of age, but has a spread of 3 feet and is obviously in good health.

Years ago spectacular economic returns arose from transplantation of exotic plants to other countries; pineapples, rubber, tea, coconuts, tulips, yams, and dates come to mind, and sea captains, alert to the demand for seeds and seedlings, were the vectors of this worldwide flow. Undoubtedly there remain treasures in foreign jungles that have not been tested on campus, but the bygone era of mass testing has largely sorted the offerings. In the case of eucalyptus in California, ornamental use has proved to be the main outcome. Wood for domestic heating is on the market but it is expensive. Many species provide a copious flow of nectar for birds and honey bees. For an authoritative history see Robert L. Santos, The Eucalypts of California, Alley-Cass Publications, 1997, and Walt Simmons, Familiar Strangers, Salmo Gardneri Publications, 1998.

Discriminating between the many different species first requires identification, for which the campus offers considerable scope. In these eucalypt entries, identification is not based purely on a botanical description but depends on guidance to a location where different species may be seen and come to be known by sight. Technical descriptions for help with difficult cases are available in Blakeley’s A Key to the Eucalypts, 3rd ed., Canberra, 1965; Dictionary of the Royal Horticultural Society, London, 2nd ed., 1956; Hortus Third, L.H. Bailey et al., Macmillan, 1976; and D.J. Boland et al., Forest Trees of Australia, Nelson, 4th ed. 1985. Also indispensable are G.M. Chippendale, ed., Eucalyptus Buds and Fruits, Canberra, 1968; and S. Kelly, Eucalypts, vols. 1 and 2 (1969, 1978).

For popular, illustrated articles on the history of eucalypts in California see “The Trees that Captured California,” Sunset, pp. 44–49, August 1956, and Roberta Friedman, “Strangers in Our Midst,” Pacific Discovery, pp. 24–30, Summer 1988. In the Bay Area, Max Watson was an influential distributor of eucalypt seedlings that he raised from imported seed, providing many of the rare species on campus.

Testimonials

Senator Ellwood Cooper’s opinion:

In India, and other parts of Southern Asia, vast areas are left without culture or occupation, overrun with jungle and forest, and totally unfit for man’s abode on account of their producing character. Already have the malaria-destroying exhalations of Eucalyptus globulus been practically proved beyond a doubt in Europe, Africa, and America. It is confidently stated that in the fatal Roman Pontine Marshes, and the no less fatal swamps of Lombardy and other parts of Italy, the Eucalyptus globulus has rendered healthy, localities in which to sleep a single night was all but certain death.
(Forest Culture and Australian Gum Trees, a Lecture delivered by Ellwood Cooper, November 26, 1875, before the Santa Barbara College Association)

Stalin’s advice:

In order to avoid the evils of swamps and combat malaria, Comrade Stalin told me, “you must plant eucalypts. This is a very good tree and it grows in many regions of our country. Mosquitoes keep well clear of this tree which grows quickly and absorbs the water of marshes.”
(Enver Hoxha, With Stalin: Memoirs, Tirana, 1979)

Bibliography of Stanford Eucalypts

Eucalypts in California

  • Cooper, Ellwood. 1876. Forest Culture and Eucalyptus Trees. Cubery.
  • Dockter, Dave, et al. 1964–2005. Max Watson’s Vasona Eucalyptus Grove.
  • Dahlsten, D.L. et al. 2005. Imported parasitic wasp helps control red gum psyllid.
  • Elkhorn Slough National Estuarine Research Reserve. Coastal Training Program; California Invasive Plant Council. June 3, 2004. Ecology and Impacts of Blue Gum Eucalyptus in Coastal California.
  • Friedman, Roberta. 1988. Strangers in Our Midst. Pacific Discovery Summer: 24–30.
  • Kinney, Abbot. 1895. Eucalyptus. B. R. Baumgardt. “No forests, no farms.”
  • Ritter, M. 2006. List of species growing (or grown at one time) in California.
  • Santos, Robert L. 1997. The Eucalypts of California: Seeds of Good or Seeds of Evil? Alley-Cass Publications.
  • Simmons, Walt. 1998. Familiar Strangers. Salmo Gardneri Publications.
  • Suddjian, David. 2004. Birds and Eucalyptus on the Central California Coast: A Love–Hate Relationship. David L. Suddjian Biological Consulting Services. A paper presented at Ecology and Impacts of Blue Gum Eucalyptus in Coastal California, June 3, 2004.
  • Tyrrell, Ian. 2001. Peripheral Visions: Californian-Australian Environmental Contacts, c. 1850s–1910; In McNeill, JR, ed. Environmental History in the Pacific World. Ashgate.
  • Tyrrell, Ian. 1999. True gardens of the gods: Californian-Australian environmental reform, 1860–1930. Berkeley: University of California Press.
  • Walther, E. 1928. A key to the species of Eucalyptus in California. Proceedings of the California Academy of Sciences XVII: 67–87.

Eucalypts on campus lacking encyclopedia entries, and species recently lost

E. cornuta, lost from the Escondido Road site, is also reported from Stanford Avenue greenbelt behind 834 Santa Fe Avenue.

E. loxophleba, E. morrisbyi, E. ochrophloia, E. pauciflora, E. squamosa, E. stellulata, and E. urnigera at 3185 Alpine Road, Prof. Bracewell’s old research site, have probably been lost since 2002. This is also the case for E. cypellocarpa [2019-NW], which can still be seen locally opposite 1015 Woodland Avenue, Menlo Park. E. dweryi present as of 11/04 and correctly located on Bracewell’s Eucalyptus Walk, was gone as observed on 5/7/06.

Illustrations: Voucher gallery.

About this Entry: The main text is from the book Trees of Stanford and Environs, by Ronald Bracewell, published 2005. Minor edits were made by Sairus Patel (Dec 2018).