HIDDEN TREASURE OF THE ARBORETUM

Catalina Ironwood floribundus Mature specimen of B y W a l t B u b e l i s Lyonothamnus floribundus ssp. asplenifolius growing in front of a Seattle home. (Photo by Walt Bubelis) anta Catalina Island lies some 26 miles off the California coast from Long Beach—a fact forever immortalized by the Four SPreps in their song “26 Miles”—and is where I E. Newton Street entrance to the Pinetum. It can first saw Lyonothamnus floribundus, while visiting take a while for young trees to put out flowers, so in 1976. if you want to see guaranteed blossoms this year, At the time, however, I didn’t give the its then the tall, narrow specimen at the Kruckeberg due, perhaps because I was distracted by all the garden is probably a better bet. other botanical wonders on the island. It wasn’t until some time later, when I saw a specimen at Two, Rare, Endemic Subspecies the Kruckeberg Botanic Garden, that I began to An unusual member of the rose family fully recognize its value as a garden tree. (Roseaceae), the Lyonothamnus is Highlights include gorgeous, glossy, evergreen monotypic, meaning that it only contains a foliage; stunning reddish-brown peeling bark; single . records indicate a wider a narrow, columnar form (especially in its early distribution of the genus into Nevada and years); and myriad small, woolly, white flowers on Oregon (as well as possible other, now-extinct the branch tips from late spring to summer. species), however, today, Lyonothamnus The tree is still uncommon in the Puget Sound floribundus is restricted to the Channel Islands Region, but there are some notable specimens off the Southern California coast. scattered about. The Arboretum just planted a There are two subspecies: Lyonothamnus small one in 2019, in the sloping bed that lines the floribundus ssp. floribundus, found only on Santa

Spring 2021 v 7 w Catalina Island and distinguished by its simple, honor: Prunus lyonii and Phacelia lyonii. linear leaves with entire leaf margins; and The “ironwood” moniker is apt: The tree’s L. floribundusssp. aspleniifolius, which is endemic wood was hard enough for sailors of that time to to Santa Cruz, Santa Rosa and San Clemente use for handspikes. Today, one would expect that islands and bears pinnately compound leaves no harvesting of wild trees is taking place. Found with deeply scalloped leaf margins. Because nowhere else on Earth besides the Channel of its attractive, fern-like (or some would Islands, and restricted to a narrow range of say marijuana-like) foliage, the subspecies habitats, wild populations of Lyonothamnus aspleniifolius is much more common in cultivation. floribundus are now classified as vulnerable to The new specimen in the Arboretum is . Conservationists are concerned Lyonothamnus floribundus spp. aspleniifolius, as about the threats to the species from wildfire, is the tree at Kruckeberg. Along with Catalina browsing by feral animals, trampling by tourists, ironwood, common names for this subspecies and climate change. include Santa Cruz Island ironwood and fern- Scientists have discovered that wild popula- leaf ironwood. tions of the tree are actually clonal groves that Both subspecies grow in canyons, ravines, have developed very slowly over hundreds of ridges and rocky slopes in chaparral and oak years by stump-sprouting. Catalina ironwood woodlands on their respective islands. In the produces little viable seed in the wild, so it’s rare wild, they can range as tall as 30 to 50 feet tall at to find a seedling popping up—and this adds to maturity; in cultivation, a range of half that size the long-term threat to the species. is more common. That said, Arthur Lee Jacobson has reported a Seattle tree measuring 45 feet tall Cultivating Catalina Ironwood on his “Plant of the Month” blog, arthurleej.com/ Gardeners can help by sheltering this beauti- plant-of-month.html. ful tree in their yards. In cultivation, Catalina ironwood can produce small seeds in abundance, Discovery & Conservation but I and others have not had much luck with The genus is named for William S. Lyon, an early germination. Softwood cuttings in summer resident of Los Angeles, who discovered the and semi-ripe cuttings in early fall are a much tree in 1884 on Santa Catalina Island. Lyon sent more reliable approach. To find it in the trade, specimens to Asa Gray, the preeminent American you’ll have to check with specialty growers, botanist of that time, who named the plant. Lyon, such as Cistus Nursery (cistus.com) near an orchid collector and author, was also the first Portland, Oregon, which offers container- state forester for California. Two other sized plants. Cistus is where the Arboretum that he found on the island are also named in his obtained its specimen.

8 v Washington Park Arboretum Bulletin FROM LEFT TO RIGHT: Catalina ironwood’s lovely, reddish-brown peeling bark. (Photo by Daderot/Wikimedia Commons) The young specimen recently planted in the Arboretum. (Photo by Niall Dunne) Fern-like foliage of subspecies aspleniifolius. Subspecies aspleniifolius in flower. (Photo by Robert Perry)

Recommended growing conditions for place in a garden with such California compan- Lyonothamnus floribundus include full sun to ions as Ceanothus and Arctostaphylos. Its beauty partial shade, well-drained soil, and little was recognized soon after its discovery. Botany summer water. The tree can be frost tender, so it’s professor E.L. Greene of the University of best to plant it in a sheltered or non-windy site. It California, Berkeley stated in 1886, “No other makes a great specimen tree for a narrow space. small tree of our coast equals this in grace of form Some find the persistent, browning seed clusters and beauty of foliage.” Who are we to argue with a bit of a turnoff, but these can be easily pruned— his assessment? m or, alternately, use the tree as a backdrop so that the seed clusters recede into the background. Walt Bubelis is a professor emeritus in They will eventually fall to the ground to create an the Horticulture Department at Edmonds interesting mulch. Community College. He is also a member of The beautiful foliage of Catalina ironwood the “Bulletin” Editorial Board. is distinctive enough to warrant a prominent

REMEMBERING the volunteer managers who came before me. Barbara Bonjour Her unflagging persistence is known among the longtime supporters of the Arboretum, and board members come up to remind me about all of her One of our most cherished work for the Florabundance Plant Sale. I could volunteers, Barbara Bonjour literally always count on her to show up and do the passed away in April of last job well.” year. A world traveler and Barbara is deeply missed, but the impact career Boeing flight engineer, of her decades of volunteer service continues. Barbara had a deep love of the Arboretum! In In early 2021, the Foundation received a very 2019, she received our Volunteer of the Year generous bequest of more than $300,000 from Award for her many contributions. Arboretum Barbara’s estate. Her legacy gift will also benefit Foundation Volunteer Resources Manager Alyssa the future of Washington Park Arboretum for Henry had this to say during the presentation: generations to come. “In her 22 years of service here, Barbara has taken on countless roles in leadership and Join our Legacy Circle: The Legacy Circle behind the scenes. When faced with an issue, honors people who have made an invest- she charges at it without flinching until she ment in the Arboretum Foundation by finds the solution. I’ve lost track of the number establishing a future gift through their will, of times she has said to me, ‘Whatever you need trust, or other form of planned giving. For more Alyssa, I will do it. ‘I’m here for you,’ and I can information, call us at 206-325-4510 or email only imagine how often she would say that to [email protected].

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