Trees in the Landscape, Part 2: Eucalyptus Spathulata Donald R
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WESTERN A rborist Trees in the landscape, Part 2: Eucalyptus spathulata Donald R. Hodel HE Mere MentION OF to coastal California. Its spreading, as the swamp mallee. However, as Eucalyptus can send shud- somewhat graceful nature, small, nar- used for this species, mallee is likely ders down many peoples’ row, attractive gray-green leaves, and a corruption of mallet; a true mallee Tspines and raise their ire to an ex- ultra smooth, colorful bark are sure to Eucalyptus has a lignotuber (round, tremely high level. This sometimes gain attention wherever it is grown. swollen rootstock from which many, violent reaction is largely due to their A tough and rugged species, it toler- slender trunks arise) and is a shrub or experiences with a few notoriously ates harsh conditions, including cold, small, shrubby tree, neither of which inappropriate species of eucalypts heat, wind, smog, aridity, saline and much applies to E. spathulata. used in the landscape that have un- alkaline soils, and sea coast exposure, For the meaning of the common fortunately jaded their assessment of and is extremely drought tolerant al- name gimlet I defer again to Matt this large, diverse, and useful genus. though occasional summer irrigation Ritter (pers. comm.) who states that Eucalyptus contains a treasure trove is beneficial in hot, desert areas. With gimlets are a small group of eucalypts of many wonderful, useful, and ap- proper management E. spathulata will from mostly western and southern propriate species, many of which are become a small to medium, useful, Australia characterized by their slen- little known and/or underutilized, and much admired tree. der, fluted, twisted, shiny trunks, and E. spathulata is one of them. A highly adaptable species, Euca- lyptus spathulata performs well and Eucalyptus spathulata performs well makes a handsome statement in the landscape, from the desert Southwest and makes a handsome statement Figure 1. Eucalyptus spathulata can in the landscape, from the desert grow up to 50 feet tall and as wide or wider and often has one or more large Southwest to coastal California. branches arising low on the trunk. Emerson Avenue, Santa Barbara, CA. Eucalyptus spathulata Hook leaves with irregularly arranged oil Taxonomy and history glands, and deeply fissured seed Synonyms: None coats. Common names: swamp mallet, nar- Etymology: The genus name Euca- row-leaved gimlet, swamp gimlet. lyptus is derived from the Greek eu, According to Kelly et al. (1983), the meaning well, and kalypto, meaning common name mallet refers to the to cover, and refers to the calyx that somewhat mallet-shaped or club- forms a lid (operculum) over the shaped fruits. However, Matt Ritter stamens and other interior organs of (pers. comm.) says that the common the flower in bud. The specific epithet name mallet (pronounced môl´ēt) re- or species name spathulata is derived fers instead to a group of species with from the Latin spathulatus, meaning a specialized tree growth form found a broad rounded upper part taper- only in Western Australia and charac- ing gradually downward into a stalk terized by mostly slender, erect stems, (spoon-like), but the precise applica- steeply angled branches, and the lack tion of the name with this species is of the regenerative structures of many uncertain. other eucalypts, such as lignotubers and epicormic buds. Some web refer- History: English botanist William ences incorrectly refer to this species Jackson Hooker (1785-1865) named Winter 2011 34 WESTERN A rborist Figure 2. (Left) Eucalyptus spathulata is often multi-trunked with two to three trunks arising at the ground, or has several large branches arising a few feet above the ground and branches are typically steeply ascending. Emerson Avenue, Santa Barbara, CA. Figure 3. (Center) Trunks of Eucalyptus spathulata can become rather large with age, up to several feet in diameter. Em- erson Avenue, Santa Barbara, CA. Figure 4. (Right) Bark of Eucalyptus spathulata is ultra smooth, mottled, colorful and showy, usually brownish gray, red- dish brown, coppery, or salmon-colored and typically with a glossy, metallic bronzy or coppery sheen. Emerson Avenue, Santa Barbara, CA. and described this species in 1844, basing it on James Drummond’s il- lustration of material from the Swan JOIN TAC River in Western Australia. TAC or the Tree Advisory Committee enables everyone to Description share their experiences and observations managing specific The description is from several sourc- trees in our landscape and urban forests for this series es (Brooker and Kleinig 1990, Chip- Trees in the Landscape. TAC is free, easy to join, and pendale 1988, Elliot and Jones 1986, open to everyone. Simply send me an e-mail expressing Kelly et al. 1983, Muller and Haller 2005) and from cultivated trees in your desire to participate in TAC. Santa Barbara, California. I will e-mail all TAC members notifying them which tree species I will be profiling in an upcoming issue ofWestern Habit/conformation: small to me- Arborist. TAC members can then respond to me about dium, long-lived, evergreen tree their experiences and observations managing that tree. 15-50 feet tall, 10-25 feet wide (Figs. 1, 9-10), infrequently shrub-like and Upcoming species to be covered in this series include then to 15 feet tall and 10 feet wide; Corymbia (Eucalyptus) torelliana, Bombax ceiba, Sapindus often multi-trunked with 2-3 trunks saponaria, and Alectryon excelsus, among others. arising at the ground or as large branches arising a few feet above the ground (Figs. 2-3), these typically Join TAC by e-mailing me: steeply ascending, sometimes single- <[email protected]> trunked; crown irregularly branched, moderately open to dense. 35 Winter 2011 WESTERN A rborist Figure 5. (Left) Adult leaves of Eucalyptus spathulata are glossy olive green, gray-green, or bluish green. Note margins of some leaves with Eucalyptus tortoise beetle feeding damage. Los Angeles County Arboretum and Botanic Garden, Arcadia, CA. Figure 6. (Right) Flowers of Eucalyptus spathulata are arranged in small, axillary, 7-flowered clusters. Los Angeles County Arboretum and Botanic Garden, Arcadia, CA. Trunk(s): to 1-2 feet in diameter or duncle flattened or cylindrical, 0.15- (sometimes forming thickets) near even more in very old specimens 0.9 inch long; buds on short pedicel, seasonal lakes, marshlands, or water (Fig. 3), typically relatively short, 0.4-0.7 × 0.1-0.3 inch, cylindrical or courses, many of which are highly sometimes fluted at the base. ovoid to broadly spindle-shaped; saline. Soils are of various drainage operculum or lid cylindrical to coni- capabilities, sandy or gravelly clays Bark: smooth, mottled, typically cal, reddish, hypanthium or base ,or heavy loams with clay subsoil, deciduous or shedding throughout greenish; flower 0.8 inch wide when alkaline or sometimes slightly acidic on branches and trunk in irregular, open, stamens erect, white or cream- and often strongly saline (Brooker and mostly small to medium patches colored (Fig. 7); summer. Kleinig 1990, Chippendale 1988, Elliot or flakes in early summer (desert and Jones 1986, Kelly et al. 1983). areas) to mid summer (coastal ar- Fruits: on short pedicel, 0.15-0.5 × eas); newly exposed bark is colorful 0.15-0.5 inch, hemispherical to ob- Propagation and growth rate and showy, usually brownish gray, conical or pear-shaped, rim thick, disc Eucalyptus spathulata is readily propa- reddish brown, coppery, or salmon- level, valves 3 or 4, exserted (Fig. 8). gated from seeds, which germinate colored and typically with a glossy, in one to two weeks. Select seeds metallic bronzy or coppery sheen Distribution and ecology from fully mature capsules (fruits), (Fig. 4), sometimes aging to gray or Eucalyptus spathulata is endemic which typically attain maturity within brownish gray by fall before the next to Western Australia where it is one year of flowering. Immediately shedding. widespread but scattered in the after collection sow seeds by scat- Avon, Eyre, and Roe Districts of the tering lightly over a pre-moistened, Leaves: simple; juvenile opposite southwestern part of the state south clean, disease-free (pasteurized), to alternate, petiole short, blade of Perth, from Albany to Esperance well drained seed, or potting mix. 2-2.75 × 0.2-0.3 inches, linear to along the coast and north to Katan- Keep evenly moist at a temperature narrow lance-shaped, dull blue- or ning and Ravensthorpe. The climate of 70 to 80 F and protect from wind, gray-green; adult alternate, petiole is distinctly Mediterranean and very dryness, and extreme cold and heat. short, 0.08-0.2 inch long, blade 1.75- similar to that of coastal and inland Transplant into individual containers 4 × 0.1-0.4 inches, lance-shaped, tip valley areas of most of California, when seedlings are sufficiently large often hook-like, glossy olive green, with warm to hot and dry, rainless to be handled easily. Grow seedlings gray-green, or bluish green (Fig. 5), summers and cool, usually moist in light shade but acclimate to full same color above and below, veins winters. Rainfall averages 12 to 15 sun quickly. Eucalypt seedlings and obscure, reticulation very sparse with inches annually. Minimum winter young plants typically grow quickly, numerous, round, conspicuous oil temperatures are in the 20s F while so move them up to larger containers glands (Fig. 7). summer maximums approach or regularly to prevent kinked, circling, exceed 100 F. girdling, or otherwise poor root sys- Flowers: arranged in small, axillary, Eucalyptus spathulata frequents tems that can be problematic later in 7-flowered clusters (Figs. 6-7); pe- low-lying areas and depressions the landscape. Peat pots/strips and Winter 2011 36 WESTERN A rborist fluted gallon (and larger) containers the intermediate and interior valleys high soil salinity up to an EC of 8 to can help to prevent such poor root of California, and the low and high 16 dS•m-1 (WON 2008) and is recom- characteristics.