I'll be honest: although its flowers are known as may flowers, and I've heard the phrase "a garland of may" used in folk song, I don't remember ever hearing the hawthorn itself referred to as the may tree. For a start, I wouldn't call it a tree: it's a bush, or a shrub. But according to not just Wikipedia but also the Woodland Trust, 'the May–tree' is one of the alternative names for the common (European) hawthorn, Crataegue monogyna.
In January 2024, I was asked what month the hawthorn flowers in. This to me is equivalent to asking what the alternative name for the may tree is; so I haven't changed this item.
It was at this time that I came across the following on Wikipedia: "The custom of employing the flowering branches [of the hawthorn or may tree] for decorative purposes on 1 May is of very early origin, but since the adoption of the Gregorian calendar in 1752, the tree has rarely been in full bloom in England before the second week of that month. In the Scottish Highlands, the flowers may be seen as late as the middle of June."
© Haydn Thompson 2023–4