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Tree to 35 m. Bark exfoliating, white and mottled. Branchlets brown or reddish brown with white or yellow tomentum. Leaves deciduous, thick and leathery, (3–)8–20(–25) × 10–20(–30) cm, broadly ovate in outline with three (to five) deltoid to triangular lobes, upper surface greyish green with sparse tomentum, soon glabrous, lower surface densely covered with interlocking white, grey or yellow tomentum, veins palmate and extending to the margins, margins entire or with triangular teeth, apex acuminate, sometimes glandular; petiole tomentose to glabrous, 3–9 cm long; stipules foliose and sharply pointed. Monoecious. Staminate inflorescences with two to four almost sessile heads; pistillate inflorescences lax, racemose or spicate, 10–26 cm long with (three to) five to seven globose heads; heads 1.4–3 cm diameter, brown. Achenes 0.5–0.7 cm long, yellowish brown. Nixon & Poole 2003. Distribution GUATEMALA; MEXICO: Chiapas, Hidalgo, Oaxaca, Puebla, Veracruz. Habitat Along streams in tropical forest, between 150 and 1850 m asl. USDA Hardiness Zone 7. Conservation status Not evaluated. Illustration NT635, NT636. Taxonomic note Platanus mexicana var. interior Nixon & J.M. Poole occurs in the Mexican states of Guanajuato, Querétaro and San Luis Potosí. It differs from typical P. mexicana in that the mature leaves have only a sparse covering of tomentum on the lower surface and there are only two to three heads in each pistillate inflorescence (Nixon & Poole 2003). The tree referred to as P. mexicana in many older works (including Standley 1922) is a separate species that has since been named P. rzedowskii Nixon & J.M. Poole. It occurs in the Mexican states of Nuevo León, San Luis Potosí and Tamaulipas, and differs from P. mexicana in that the leaves are usually five-lobed, and both the staminate and pistillate inflorescences are composed of a single globose head (Nixon & Poole 2003). It is not known to be in cultivation.
Platanus mexicana is now well established in American commercial and amenity horticulture, being particularly valued for its tolerance of hot dry conditions in the arid southern parts of the United States, used – as is traditional for planes – as a street tree. It forms a large tree with striking pale exfoliating bark, while the leaves are attractively bicoloured, showing their white-hairy undersides in a breeze, in just the same way as Tilia tomentosa ‘Petiolaris’. ‘Alamo’ is a trademarked name for a large-leaved clone said to be resistant to anthracnose, powdery mildew and other fungal diseases (Orange County Nursery 2005), but it is not clear if this is a selling name or a cultivar epithet; if the latter it is illegitimate, as Alamo is the Spanish vernacular name for Platanus species (L. Hatch, pers. comm. 2008). Although most frequently cultivated outside our area, P. mexicana will grow further north, as demonstrated by a beautiful and vigorous tree at the JC Raulston Arboretum (labelled P. lindeniana). Planted at 25 cm in 1999, it is currently approximately 10 m tall, and another specimen (since removed) achieved 6 m in four years (M. Weathington, pers. comm. 2008). There are also large specimens in Virginia (R. Olsen, M. Weathington, pers. comms. 2008). It does not seem to be frequently grown in the Pacific Northwest, however. Platanus mexicana has not so far proved very successful in the United Kingdom, the only specimen reported by Johnson (2007) being a tree at the Sir Harold Hillier Gardens grown from Frankis 134, collected in 1991, which reaches about 3 m annually before dying back in winter.
Platanus racemosa var. wrightii (S. Watson) Benson (see Bean and Krüssmann: B277, K418), from Arizona, New Mexico, Chihuahua and Sonora, is another drought-tolerant plane, widely planted in the southern and western United States but seldom seen further north. It has a darker trunk, especially at the base, and lacks the white indumentum of P. mexicana.