Those plants are scurvy-grass, lovage, and sneezewort. Quote: "These plantes are moste efficacious in the inflaming of the braine, and are therefore much used in Confusing and Befuddlement Draughts, where the wizard is desirous of producing hot-headedness and recklessness...." ...Hermione said Sirius was becoming reckless cooped up in Grimmauld Place.... "...moste efficacious in the inflaming of the braine, and are therefore much used..." ...the Daily Prophet would think his brain was inflamed if they found out he knew what Voldemort was feeling... "...therefore much used in Confusing and Befuddlement Draughts..." ...confusing was the word, all right; why did he know what Voldemort was feeling? What was this weird connection between them, which Dumbledore had never been able to explain satisfactorily? "...where the wizard is most desirous..." ...how he would like to sleep... "of producing hot-headedness..." ...It was warm and comfortable in his armchair before the fire, with the rain still beating heavily on the windowpanes and Crookshanks purring and the crackling of the flames.... The book goes on after that.
The book being read is Magick Moste Evile