From Chapter 3:
The fumes of dried coltsfoot leaves were used as a remedy in cases of difficulty of breathing, both in ancient Roman times and in Tudor England. Lyte, in his translation, 1578, of Dodoens' "Historie of Plants," says of coltsfoot: "The parfume of the dryed leaves layde upon quicke coles, taken into the mouth through the pipe of a funnell, or tunnell, helpeth suche as are troubled with the shortnesse of winde, and fetche their breath thicke or often, and do [sic] breake without daunger the impostems of the breast." The leaves of coltsfoot and of other plants have often been used as a substitute for tobacco in modern days. A correspondent of Notes and Queries, in 1897, said that when he was a boy he knew an old Calvinist minister, who used to smoke a dried mixture of the leaves of horehound, yarrow and "foal's foot" intermingled with a small quantity of tobacco. He said it was a very good substitute for the genuine article. Similar mixtures, or the leaves of coltsfoot alone, have often been smoked in bygone days by folk who could not afford to smoke tobacco only.

From Chapter 6:
smoking was still popular also at Oxford. A. D'Anvers, in her "Academia; or the Humours of Oxford," 1691, speaks, indeed, of undergraduates who, when they could not get tobacco, did much as the parson of Thornton is reputed to have done, as already related in Chapter II, i.e. they condescended to smoke fragments of mats. With this may be compared the macaronic lines: