Hallucinogens 1 (up to 1950s) - 10 items, including The Boston Daily Globe 1956 "Columbian Jungle Area Untouched by Civilization."

Hallucinogens 2 (1960s) - 42 items, including The Coral Gables Times 1968 "Hallucination Drug Cult Faces Legal Test."

Hallucinogens 3 - 17 items, including The New York Times 1978 "Doctor Links Indian Art to Drugs."

Hallucinogens 4 - 14 items, including The Seattle Times 1985 "Botanist Says He's Unmasked Mystery," Newsweek 1982 "Guns, Grass and Money."

Halophytes - 2 items.

Hamamelis - 3 items.

Hats - 14 items, including Field Museum News 1939 "Straw Hats," Gardeners' Chronicle 1915 "The Bamboo Hat Industry."

Hay Fever - 25 items, including New York Times 1982 "Mushroom Spores Suspected as Culprit in Allergic Reactions that Baffled Specialists," Newsweek 1982 "Allergies: New Discoveries, New Relief."

Helianthus - 28 items, including The New York Times 1983 "An Artichoke to Grow in the Sun," The Garden 1918 "A Sunflower Village."

Heliotropium - 1 item

Helleborus - 2 items

Hemerocallis - 1 item

Hemlock - 4 items, including The Garden Magazine 1910 "Is the Southern Hemlock Better."

Hemp - 8 items, including Commerce Reports 1931 "Hemp Experiments in Colombia.”

Hepatica - 3 items

Herbals - 6 items, including The New York Times 1981 "Medieval Manuscripts."

Herbaria - 2 items

Herbicides - 7 items, including The New York Times 1982 "Panel Sees Problem in Study of Effects of Agent Orange."

Herbs 1 - 32 items, including The Garden 1925 "Some Culinary Herbs Worth Cultivating," The Gardeners' Chronicle 1929 "Curious Old Beliefs About Medicinal Herbs."

Herbs 2 - 45 items, including Life 1961 "A New Urge for Herbs," Field Museum News 1941 "Medicinal Science Was Father of Botanical Studies."

Herbs 3 - 61 items, including The Real Paper 1981 "Consumer Beware: Unhealthful Herbs,” New York Times 1977 "Herbs to Grow for Refreshing Cups of Tea," The American Weekly 1959 "The Search for Life-giving Herbs."

Herb-Clip - 8 items

Hernandia - 1 item

Hevea - 16 items, including Arnoldia 1984 "The Tree that Changed the World in One Century" by Richard Evans Schultes.

Hibiscus - 17 items, including The Agricultural News 1904 "Musk Seed."

Hickory - 5 items, including The New York Times 1936 "Hardest Wood Used for Skis."

Hieracium - 1 item

Hippophae - 2 items

Hoheria - 1 item

Holcus - 2 items

Honey - 24 items, including The New York Times 1983 "Radioactivity Found in Bees."

Hops - 10 items

Horticulture - 53 items, including The Boston Globe 1981 "Plants Can Be an Educational Hobby," The New York Times 1936 "Patents for Plants."

Hura - 1 item

Hydrastis - 1 item

Hydrilla - 1 item

Hydroponics - 3 items

Hypericum - 1 item

Hyptis - 1 item