Laudator Temporis Acti

Thomas Pakenham, The Remarkable Baobab (New York: W.W. Norton & Company, 2004), p. 9, quoting Michel Adanson, A Voyage to Senegal, the Isle of Goree and the River Gambia, tr. anon. (London, 1759), pp. 96-97:

I laid aside all thoughts of sport, as soon as I perceived a tree of prodigious thickness, which drew my whole attention... I extended my arms, as wide as I possibly could, thirteen times, before I embraced its circumference; and for greater exactness, I measured it round with packthread, and found it to be sixty-five feet.

Henry Hitchings, Defining the World: The Extraordinary Story of Dr Johnson's Dictionary (New York: Farrar, Straus and Giroux, 2005), aka Dr Johnson's Dictionary: The Extraordinary Story of the Book that Defined the World, p. 60:

Besides, there were more immediately analgesic rewards to be had from visiting the Strahans' home. In the courtyard stood a lime tree which Johnson, in moments of abstraction, liked to hug.

When Walt Whitman hugged trees, it was more like a bear hug than a tender embrace (Spring Overtures—Recreations, from Specimen Days):

A solitary and pleasant sundown hour at the pond, exercising arms, chest, my whole body, by a tough oak sapling thick as my wrist, twelve feet high—pulling and pushing, inspiring the good air. After I wrestle with the tree awhile, I can feel its young sap and virtue welling up out of the ground and tingling through me from crown to toe, like health's wine.

See also Whitman's The Oak and I, from the same book:

I write this, 11 A.M., shelter'd under a dense oak by the bank, where I have taken refuge from a sudden rain. I came down here, (we had sulky drizzles all the morning, but an hour ago a lull,) for the before-mention'd daily and simple exercise I am fond of—to pull on that young hickory sapling out there—to sway and yield to its tough-limber upright stem—haply to get into my old sinews some of its elastic fibre and clear sap. I stand on the turf and take these health-pulls moderately and at intervals for nearly an hour, inhaling great draughts of fresh air. Wandering by the creek, I have three or four naturally favorable spots where I rest—besides a chair I lug with me and use for more deliberate occasions. At other spots convenient I have selected, besides the hickory just named, strong and limber boughs of beech or holly, in easy-reaching distance, for my natural gymnasia, for arms, chest, trunk-muscles. I can soon feel the sap and sinew rising through me, like mercury to heat. I hold on boughs or slender trees caressingly there in the sun and shade, wrestle with their innocent stalwartness—and know the virtue thereof passes from them into me. (Or may-be we interchange—may-be the trees are more aware of it all than I ever thought.)