Quercus × morehus Kellogg

Quercus × morehus was described as a species by American botanist Albert Kellogg in 1863, based on a specimen sent to him by Andrew A. Veatch, who had found it near the margin of Clear Lake, California. At the time, only one plant was known, which Kellogg described as a low, shrubby tree about 10 m tall and of little value.

It is in cultivation in oak collections in the UK. At Borde Hill, West Sussex, a tree was 12 m tall and 34 cm dbh in 2015 (The Tree Register 2025). Dorothy Holley collected seed in California in 1997 (DH 143), and a tree from this collection at Chevithorne Barton, Devon, was 6 m × 12 cm in 2017. Two others from the same collection are at the Sir Harold Hillier Gardens, the larger 9.3 m × 17.2 cm in 2023 (B. Clarke, pers. comm. 2025). A further introduction of seed collected in California to Chevithorne Barton in 2000 has given a tree of 8 m × 15 cm in 2017 (The Tree Register 2025). It can also be found at Westonbirt Arboretum, Gloucestershire, and High Beeches, West Sussex, from seed collected on Mt Palomar, California, and planted in 2001 (High Beeches Garden 2025).

Two plants are at Arboretum des Pouyouleix, France; it is also represented at Arboretum national des Barres, France, at Arboretum Trompenburg, the Netherlands, and at Meise Botanic Garden, Belgium.

In the USA it is represented by trees at the California Botanic Garden and the University of California Botanical Garden at Berkeley.

According to Russell (2019) Oracle Oaks can be most easily found in winter when they have lost many of their leaves, making them distinguishable from the deciduous and evergreen species they grow with.

This hybrid has had problems with both its scientific and common names. Kellogg chose the epithet to honour the oak grove of Moreh, mentioned in Genesis 12:6. According to Greene (1887–1889​​​​​​), Kellogg had been trained by Wesleyan parents with daily readings of the Bible, especially of the Old Testament, and he was an ardent disciple of Emanuel Swedenborg (1688–1772), the Swedish theologian. The oak grove of Moreh had special significance in Swedenborg’s teachings. In Arcana Cœlestia (1749–1756), one of his major works, Swedenborg explains the books of Genesis and Exodus as a symbolic description of the process of spiritual growth in the individual. Genesis 12, in which God tells Abram to leave his country and family and enter a land that God will show him, is taken to represent the passage from childhood to adolescence in five phases marked by Abram’s journey. The third phase is the oak grove of Moreh, which represents the dawn of perception. According to Swedenborg, ‘[i]n heavenly people, the ability to understand is compared to a garden filled with all kinds of trees. Rational capacities are compared to a forest of cedar … [b]ut facts are like oak groves, since they resemble the tangled branches that oaks have’ (Swedenborg 2012). It appears that Kellogg was sufficiently impressed by Swedenborg’s interpretation to wish to name a Californian oak – somewhat arbitrarily – after Moreh. Another of Kellogg’s names was taken from the Bible: the genus Marah, taken from the Hebrew meaning ‘bitter’. In his description, he even mentions the Biblical reference (Kellogg 1854).

Kellogg was not a trained botanist or classicist: his Latin terminology and way of making Latin adjectives were ‘somewhat original,’ and some of his names have had to be subsequently corrected to conform with the rules of Latin grammar (Greene 1887–1889). Understanding the epithet ‘morehus’ to be adjectival, some changed the spelling to ‘moreha’, but it is now believed Kellogg intended it as a noun that should not be declined. This is debatable: he also published the name Q. chrysophyllus, which suggests he understood (incorrectly) that Quercus takes masculine adjectives.

Kellogg used the name ‘Abram’s Oak’ in his original description (Abram’s name did not change to Abraham till Genesis 17). Lamb (1916) proposed the name ‘Moreh Oak’ to replace the name ‘morehus oak’, which he stated had come into use in forestry literature (e.g., Sudworth 1897; Jepson 1909, 1910) and which he regarded as without meaning and grammatically incorrect. Jepson (1923–1925) used the name ‘Oracle Oak’. Moreh’s oak is thought by some to be the same tree referred to as the ‘Diviner’s oak’ or ‘Oracle’s oak’ in Judges 9:37; this is presumably the source for Jepson’s common name. According to some translations, the tree at Moreh was not an oak but a terebinth (Pistacia terebinthus), but Swedenborg clearly understood it to be an oak grove (“quercetum Moreh” in his Latin original).