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Julian Sutton (2021)
Sutton, J. (2021), 'Arbutus arizonica' from the website Trees and Shrubs Online (treesandshrubsonline.
Small tree, 3–8(–10) m, with dense, compact crown. Bark of trunk and major branches grey, thick, chequered with squarish plates, red and peeling on smaller branches and twigs. Leaves lanceolate, more broadly so in the south, (2.5–)3–7.5(–9) × (1–)1.8–3(–4) cm, base usually tapered, apex acute to slightly acuminate, margins entire (sometimes serrate on vigorous sprouts), coriaceous, glossy olive green green above, lighter green beneath, glabrous on both surfaces; petiole 2–3 cm, often red. Inflorescence a cluster of racemes, often dense, pedicels densely hairy, lengthening to 1.6 cm in fruit. Flowers held obliquely above or below the horizontal; corolla urceolate, 5–6 mm, creamy white, ovary glabrous; flowering from early March in the south, typically May to June in the north. Fruits rounded, 6–9 mm across, ripening to a rich blackish red in August to October. (Sørensen 1995, Sørensen 2009, Grimshaw & Bayton 2009).
Distribution Mexico Sierra Madre Occidental from Sonora and Chihuahua south to Jalisco United States SE Arizona, SW New Mexico
Habitat Forest along seasonal waterways in north, southward in seasonally dry montane zone with Pinus, Quercus, Arctostaphylos, and other Arbutus, 1500–2400 m.
USDA Hardiness Zone 8-9
RHS Hardiness Rating H4
Conservation status Least concern (LC)
Essentially a western Mexican species, just crossing the border into the southwestern United States, this is an undeservedly rare species in cultivation. Greater experimentation, and introduction of northerly material from the highest elevations are beginning to establish Arbutus arizonica in the US Pacific States (Grimshaw & Bayton 2009, Hogan 2008), where it is ‘much more garden tolerant’ than A. menziesii (One Green World 2021). It also has untapped potential for the Atlantic fringe of Europe.
The Arizona Madrone is distinguished from other species in the Americas by its combination of glabrous leaves, tapered at the base, with bark which peels in strips only on young, thin branches, the mature bark making chequered plates. Characteristically a tree of open oak-pine forest (Brown 1982), it is drought tolerant and survives fire by resprouting from epicormic buds (Barton 2009). The US champion grows in Santa Cruz Co., AZ (9.8 m × 340 cm, 2020 – American Forests 2021).
Collections made by Oregon nurseryman Sean Hogan in the Chiricahuan Mountains of SE Arizona (S.B. Hogan 4926 & 4939 of 1991) have proved significant (Grimshaw & Bayton 2009). Trees from both these collections are well established at the University of California Botanical Garden, Berkeley (University of California Botanical Garden 2021), and are increasingly offered by nurseries in California, Oregon and the desert southwest, marketed for street and xeric plantings (Cistus Nursery 2021, One Green World 2021).
Natural hybrids between A. arizonica and A. xalapensis are suspected in the Animas Mountains of New Mexico, where they make limited contact (Sørensen 2009).