Hastings' Dictionary of the Bible (1898)
HEM'LOCK, Hos 10:4. A well-known bitter and poisonous herb, a species of which is common in the United States. The word rendered "hemlock" in the above passage and in Am 6:12 is elsewhere rendered "gall." The figurative use of it is explained by comparing the above passage with Deut 29:18; Am 5:7; Heb 12:15. The evils of perverted judgment resemble the springing up of useless and poisonous plants where we look for and expect valuable and
nutritious vegetation.