PalmArbor PalmArbor, an electronic journal published periodically, includes articles on the identification, taxonomy, nomenclature, selection, propagation, and landscape management of palms, trees, and other woody plants. Content will be of interest to botanists, horticulturists, arborists, nurserymen, and landscape managers, designers, and architects. Articles are popular and/or technical in nature; a peer-review track is available. Contact the Editor-in-Chief to submit articles or for other information. Editor-in-Chief Donald R. Hodel University of California, Cooperative Extension Los Angeles [email protected] 626-586-1973 © 2015, Donald R. Hodel. All rights reserved. No portion of this work may be reproduced or transmitted in any form or by any means, electronic, mechanical, or otherwise, including but not limited to photocopying, scanning, and recording, or by any information storage of retrieval system. Each author holds the copyright for his or her work. PALMARBOR Hodel: Alectryon excelsus Vol. 2015-1 2015 Trees in the Landscape, Part 11: Alectryon excelsus subsp. excelsus Donald R. Hodel University of California Cooperative Extension 700 W. Main Street Alhambra, CA 91801 [email protected] Alectryon excelsus raspberry and you have a fairly accurate subsp. excelsus Gaertn. picture of the curious and eye-catching seeds (appearing nearly good enough to eat!), This New Zealand native, a long-lived, which are sure to draw attention in the moderately growing, small to medium, garden or landscape (Fig. 1). It performs evergreen tree typically of good structure well in coastal plains and valleys from San with handsome, glossy, dark green pinnate Diego to San Francisco and is perhaps leaves and amazing if not spectacular seeds, somewhat drought tolerant in central makes a fine shade, specimen, park, California but probably needs regular water residential, and even street tree. The seeds in the southern part of the state to look its are indeed remarkable: imagine a black best. licorice gumdrop embedded in a ripe red Fig. 1. The amazing if not spectacular seeds of tītoki appear like a black licorice gumdrop embedded in a ripe red raspberry (Casa del Prado, Balboa Park, San Diego, CA). PALMARBOR 2015-1: 1-13 1 PalmArbor Hodel: Alectryon excelsus Vol. 2015-1 2015 Taxonomy and History Description Common Names: New Zealand ash, New The description is from Allan (1961), Zealand oak, tītoki (Māori). Early European Cheeseman (1925), de Lange et al. (1999), settlers in New Zealand called it ash and McClintock (2001), Muller and Haller later oak but the preferred term now is its (2005), Puplava and Sirois (2001), Salmon Māori name (Parsons 2014). (1980), and supplemented from cultivated specimens in California. Etymology: The genus name Alectryon is the Greek word for cockscomb and likely Habit/Conformation: medium, slowly to alludes to the red, fleshy, granular aril moderately growing, broad-leaf, evergreen surrounding the seed that resembles a unarmed, monoecious tree to 60 feet tall and rooster’s cockscomb in color and texture. 40 feet wide (Fig. 2); much branched; The specific epithet excelsus is from the canopy variable and irregular but generally Latin excelsa, meaning tall or lofty, and tending to be rounded to broadly columnar, perhaps alludes to the tall stature of this tree typically dense but sometimes open. in comparison to adjacent trees in its native habitat. Trunk: typically single, rarely multiple, History: Joseph Gaertner (1732-1791), a usually irregular and twisting, to 24 inches German botanist best known for his early DBH (Fig. 3). works on seeds, De Fructibus et Seminibus Plantarum, named this species in that book Bark: gray to dark gray or nearly black, in 1788, basing it on material from New smooth (Fig. 4). Zealand. Fig. 2. Tītoki is a medium, slowly to moderately growing, broad-leaf, evergreen tree tending to form an irregularly rounded canopy (Stowe House, Goleta, CA). 2 PalmArbor Hodel: Alectryon excelsus Vol. 2015-1 2015 Fig. 3. Tītoki typically has a solitary trunk but sometimes has Fig. 4. Bark of tītoki is gray and smooth (Stowe House, Goleta, low multiple branches (Stowe House, Goleta, CA). CA). Leaves: unevenly pinnate, alternate; petiole on pedicels 0.2 inch long; calyx cupular but 3 inches long; blade 6-13 × 4-8 inches, deeply cleft into 5 triangular, acute lobes, oblong; 3-7 pairs of pinnae and a single bases joined; stamens 6-8, anthers large, terminal one, these 1.75-4.25 × 0.75-1.60 dark red, on fine, thread-like stalks; ovary inches, ovate-lanceolate to ovate-oblong, hairy; all parts of inflorescence and flower deep glossy green adaxially (upper) (Fig. 5), with dense, short, soft, silky, rusty brown paler abaxially (lower), +/- thin-textured, hairs especially when young. acuminate to obtuse or subacuminate, margins smooth or remotely toothed; twigs Fruits: more or less woody capsule, 1- or 2- and leaves with dense, short, soft, silky, lobed, 0.30-0.50 × 0.25-30 inch, brown, rusty brown hairs especially when young. swollen, with a ridge along one side ending in a spur, with dense, short, soft, silky, rusty Flowers: in much open and branched brown hairs especially when young, mid to terminal panicles 4-12 inches long at branch late summer, one year after flowering; seeds tips in the spring and early summer (Fig. 6); 0.30 × 0.25 inch, glossy jet black, globose, flowers bisexual or staminate (male), half embedded in fleshy, granular, scarlet, lacking petals, purplish (Fig. 7), small, 0.10- cup-shaped aril (specialized outgrowth of 0.15 inch wide, inconspicuous but fragrant, the attachment point of the seed or seed stalk) (Figs. 1, 8). 3 PalmArbor Hodel: Alectryon excelsus Vol. 2015-1 2015 Fig. 5. Leaves of tītoki have three to seven pairs of glossy green pinnae (Stowe House, Goleta ,CA). Distribution and Ecology The Sunset Western Garden Book (Brenzel 1999), tītoki performs adequately in coastal Tītoki occurs in moist to wet, lowland forest, California from San Diego in the south to mostly on alluvial soils, from sea level to the Bay Area in the north, meaning it is 2,000 feet elevation on the North and South likely adapted to Sunset Zones 15, 16, 17, Islands of New Zealand. It is common and and 20 to 24 although it is marginal in Zones widespread on the North Island but on the 20 and 21 because of severe heat and aridity. South Island is found from the Banks Indeed, extreme heat, aridity, and cold of Peninsula to central Westland. Rainfall areas farther inland likely preclude its use varies but generally is distributed throughout there. Its U. S. D. A. Cold Hardiness ranking the year, peaking in the winter months and is probably zones 9 and 10. Old, mature declining somewhat in the summer although specimens will probably tolerate even in the summer each month has temperatures to about 20 F with minimal significant precipitation. Average daily damage although young plants might be temperatures range from the 50s to 60s°F. damaged at higher temperatures. Tītoki is Frosts are uncommon, especially in the likely not well adapted to the desert areas of northern part of its range but become more southern California, western Arizona, and frequent and severe in the south. southern Nevada. It would likely perform well in cooler, upland areas of Hawai‘i, such Environmental Tolerances as on the Big Island and Maui, but the risk of it becoming invasive needs to be Although experience with tītoki is limited, it determined (which see below under is surprisingly tolerant and adaptable despite Weed/Invasive Species Risk). its origin in moist to wet, somewhat moderate to cool areas. Although unlisted in 4 PalmArbor Hodel: Alectryon excelsus Vol. 2015-1 2015 Tītoki seems especially well adapted to the Propagation and Growth Rate cool, moist, foggy, humid conditions of the coast and might actually perform slightly Tītoki can be readily propagated by seeds, better in the Bay Area. It tolerates wind; which are typically available in mid to late however, it is intolerant of ocean and/or salt- summer in California. Seeds germinate laden wind (Parsons (2014). Tītoki does readily within a month or so if handled tolerate light or heavy soils as long as they correctly (Metcalf 1995 and personal are well drained. It appears very well observation). Sow seeds in a clean, moist, adapted to and grows best on deep alluvial well drained and aerated medium and soils (Salmon 1980). Tītoki seems to do maintain the temperature at about 70 to better in slight acid rather than alkaline soils 75°F. Metcalf (1995) reported that seeds, and is likely intolerant of poor drainage. The which can take 12 months to attain maturity, most limiting factors in its wider use might can be dry-stored for four to five months and be intolerance of severe cold and the still germinate fairly well although extreme heat and aridity of inland and desert immediate planting gives the best results. areas. Start seedlings in light shade but acclimate them to full sun after about a year. Cave and Although not investigated, drought tolerance Paddison (1999) reported that young trees of tītoki is likely low and trees probably need sheltering and protection, especially need regular irrigation, especially in from heavy frosts. warmer, more arid interior areas. However, Barry Coate (pers. comm.) reports that an Tītoki has a moderate to fast growth rate established tree in San Jose looked adequate when young in coastal California, attaining if not fine after 20 years without irrigation. four to five feet in height after three years from seed. Growth tends to slow in older plants with trees in California typically Fig. 6. Flowers of tītoki are in much branched terminal panicles in spring and summer (Zoro Gardens, Balboa Park, San Diego, CA).