Quercus emoryi Torr.

It is perhaps appropriate that Emory Oak was discovered by an officer in the US Army: it displays an almost military ruggedness, surviving on rocky ground with little or no topsoil, tolerating hot, dry conditions, and proving extremely hardy. In the wild it grows on different soils or types of rock, ranging from fine alluvial fills to gravel and cobble arroyos (streams), limestone to granite, and mercilessly draining sandstone hilltops. It thrives on acidic soils and on limestone manages to grow on pockets of volcanic soil. Depending on soil type, it will adopt different habits, from the minimal to the monumental, as a shrub a few metres high or as a massive tree 20 m tall and 30 m wide, or even stretching to 30 m in height. For Melendrez (2000) these trees resemble the southern live oak (Q. virginiana) of the US Southeast, with large horizontal branches swooping down to the ground and tall, domed crowns; for le Hardÿ de Beaulieu & Lamant (2010), these tabular giants recall African acacias; for Lyndon et al. (2021) they have canopies ‘like stacked umbrellas.’ Sternberg (2004) raved about the then US National Champion in Glenwood, New Mexico, which, though a shell of its former self, having lost two of its three primary ascending limbs, exceeded any other Emory oak ever measured, at 24.3 m tall, 21.6 m across and 1.8 m dbh. It has since succumbed and its place taken by a giant in Grant Co., New Mexico, 18.3 m in height, 22.9 m crown spread and 1.7 m dbh (Russell 2018; American Forests 2024). It can also be long lived: Melendrez claims to have counted over 600 annual rings on branch cuts 1.2 m in diameter.

Massive size and longevity often come at the cost of slow growth, as attested by the density of those growth rings. This seems to be the case in the wild, where according to Melendrez slow growth is the result of the aridity of the habitat. In cultivation, however, growth can be swifter: a tree at Arboretum de la Bergerette in southwestern France, planted in 2004, reached 9.4 m × 17 cm in 2018 (S. Haddock pers. comm.); at Silwood Park, Berkshire, UK, a tree planted in 1991 measured 11 m × 19 cm in 2017, thus achieving UK Champion status according to The Tree Register (2024); other plants in the UK have stalled at a height of around 3 or 4 m. The species is found in collections in the US West Coast and Southwest and also in Australia (Royal Botanic Gardens Victoria, Melbourne) and Argentina (Grigadale Arboretum) (P. Berbee pers. comm. 2024; pers. obs. RC).

The species is usually described as hardy to zone 6 (Sternberg 2004; Grimshaw & Bayton 2009), or zone 7 (le Hardÿ de Beaulieu & Lamant 2010; Edwards & Marshall 2019), though Melendrez stretches it to zone 4, based on his experience planting it in a high-elevation test plot near Chana, New Mexico, at around 2400 m elevation.

New leaves emerge pinkish and clad in white tomentum, providing ornamental value in gardens. The leaves also prove attractive to Pronghorn, White-tailed deer and Mule Deer in natural habitat in the US Southwest, though reports of their importance, based on rumen and faecal analyses, vary (Pavek 1994). References agree, however, that leaves and acorns of Emory Oak are of key importance to wildlife, including quail and Wild Turkey, and to livestock (Peattie 1953). The acorns are particularly palatable and agreeable even to humans. Unlike most other acorns, particularly those in Section Lobatae, Quercus emoryi acorns are low in tannins and require little or no leaching prior to eating. They are rich in nutrients, fats, and protein, and were a critically important commodity of the Apache Tribes of the US Southwest, as a food source and also for use in ceremonies. According to Coder et al. (2005), excursions to gather acorns were social events that involved all generations, and ground acorns were ‘always on the table, like salt and pepper.’ Peattie (1953) comments that ‘by a strange coincidence’ the area where the Apache had their strongholds coincides almost exactly with the range of the species. In view of the importance of balanoculture (economy based on acorns) to early humans (see Logan 2005; Chassé 2016), it is likely that the coincidence is not strange at all and that the Apache settled only where their staple diet was abundant. Emory Oak acorns continue to be used as food today: Chassé (2011) reports of a nursery in Mexico that specialises in growing Emory Oaks because the acorns are a food source and are sold in local markets; according to Martínez (1954), ground Q. emoryi acorns are commonly combined with wheat flour to make biscuits.

The mature foliage also draws plaudits for its shiny green colour. Peattie (1953) waxes lyrical about the species, his imagery clearly impacted by the oak’s presence at Apache Pass, the site of treachery and a cruel battle in 1862 during the Apache Wars: ‘the Apache’s Oak stands proudly, its zigzag twigs as tough to break as sinewy savage arms, its leaves in the brilliant Arizona sunlight glittering almost painfully, or under a full moon twinkling like lance points.’

It is unclear when it was first introduced to cultivation in the UK and Europe. Le Hardÿ de Beaulieu & Lamant (2010) propose 1997, presumably in reference to plants at Sir Harold Hillier Gardens that bear accession numbers with that year; they mention a second introduction by Thierry Lamant and Eike Jablonski in 2001 of seed collected in New Mexico. The tree growing in Silwood Park in the UK, planted in 1991, would antedate that (M. Crawley, pers. comm. 2024), but another tree at the Sir Harold Hillier Gardens, of unknown origin and pre-1979 planting date, is apparently earlier still; this tree measured 7.4 m × 13 cm in 2017 (Royal Botanic Garden Edinburgh 2024). A tree growing at Royal Botanic Gardens Victoria in Melbourne, Australia, accessioned in 1988 and sourced from California, measured 11.5 m × 49 cm dbh in 2024, which would make it the champion in cultivation worldwide (P. Berbee, pers. comm. 2024).

The species was first described in 1848 by John Torrey, who named it in honour of William Hemsley Emory. Though Emory collected the plant while participating in a military expedition, he was not an ordinary soldier. Lt. Emory belonged to the Corps of Topographical Engineers, a branch of the army charged with gathering scientific information while serving as part of the fighting force. Known familiarly as the ‘topogs’, they had been educated at West Point, and their courses included engineering, drawing and natural science. John Torrey (1796–1873), one of the most important leaders in the early development of scientific botany in 19th century US, instructed them in botany and taught them how to document the flora of areas through which they would travel. Emory was one of the topogs with the army of the west during the march to California in 1846. Despite hard marching, scarcity of food and water, and the constant threat of combat, he took time to collect specimens that he later sent to Torrey for cataloguing. Torrey’s descriptions were published as an Appendix to Notes of a military reconnoissance, from Fort Leavenworth, in Missouri, to San Diego, in California, including parts of the Arkansas, Del Norte, and Gila rivers, Emory’s report to the US Congress (Emory 1848). The report included one new genus and nine new species, including the oak named in honour of Emory, by then ascended to the rank of Major (Hill 2012; Dickerman 1985).