Mulberries show up quite a bit in my novels and in my worlds. This is true more of the recent work than the early efforts, but the trees are there even back in the ‘Donzalo’s Destiny’ novels. For that setting, it was primarily a result of my knowing they were important for the feeding of silkworms. That and the climate was suitable.
It was when I began researching for my quasi-Polynesian people of the Malvern and Mora trilogies, that they really showed up. At first, because I was looking into the making of bark cloth. My reading showed that mulberries, in their varied species, were extraordinarily useful. Cloth and paper from the bark, rope from the roots, quick-growing wood, and, of course, fruit.
The only thing that rivaled them was the somewhat related breadfruit. Which also appears, naturally. Both tend to be a bit bland as a food. To be sure, there are comments on this. People eat a lot in my books and talk about it too.
By the way, I have eight good-sized mulberry trees in my own yard, ones I planted soon after moving here. They certainly do grow rapidly and the fruit, if not exciting, is pleasant enough. That is, on the trees that bear fruit; three are males but those are necessary too!
I’ve mentioned the silk connection very peripherally in the writing. It is not important to the ‘Donzalo’ sequence (though I think it is an major industry, one I shall explore when I return to that world). I spoke of silk production being common among the villages of the Ildin in ‘The Ways of Wizardry’ but did not explore the mulberry connection there. Again, when I return to that series, perhaps I shall find reason.
There is no particular need — when such things become important, they are dealt with. Most of the time, a mention here or there is all we want; anything more gets in the way of the story. But I, the writer, should be aware of these underpinnings of my worlds. I should know that this people or that does grow a certain tree, and why.
That’s how we keep our tales ‘rooted.’ :)