- Iberis gibraltarica
- Iberis sempervirens
- Iberis umbellata
- Ichnocarpus frutescens
- Ilex aquifolium
- Ilex cassine
- Illecebrum verticillatum
- Impatiens balsamina
- Impatiens noli-tangere
- Indigofera tinctoria
- Inula britannica
- Inula crithmoides
- Inula helenium
- Inula hirta
- Inula salicina
- Ionactis linariifolia
- Ipomoea alba
- Ipomoea coccinea
- Ipomoea lacunosa
- Ipomoea quamoclit
- Ipomoea triloba
- Ipomoea violacea
- Iris foetidissima
- Iris germanica
- Iris graminea
- Iris persica
- Iris pseudacorus
- Iris pumila
- Iris sibirica
- Iris spuria
- Iris variegata
- Iris verna
- Iris versicolor
- Iris virginica
- Iris xiphium
- Isatis tinctoria
- Isolepis fluitans
- Isolepis setacea
- Itea virginica
- Iva annua
- Iva frutescens
- Ixora coccinea
Isatis tinctoria
- Woad (Isatis tinctoria)
- In addition to producing a blue dye, woad has alleged medicinal uses. Chemicals from woad might be used to prevent cancer, as woad can produce high levels of glucobrassicin.<wiki/List_of_medicinal_plants#cite_note-219"> Young leaves when damaged can produce more glucobrassicin, up to times as much.<wiki/List_of_medicinal_plants#cite_note-220">
- Indigo woad Root is a traditional Chinese medicine herb that comes from the roots of woad, but often incorrectly listed under the synonymic name, Isatis indigotica. It is also known as Radix isatidis. The herb is cultivated in various regions of northern China. The roots are harvested during the autumn and dried. The dried root is then processed into granules, which are most commonly consumed dissolved in hot water or tea. The product, called banlangen keli (复方板蓝根颗粒), is very popular throughout China, and used to remove "toxic heat", soothe sore throat and to treat influenza, measles, mumps, syphilis, or scarlet fever. It is also used for pharyngitis, laryngitis, erysipelas, and carbuncle, and to prevent hepatitis A, epidemic meningitis, cancer and inflammation.<wiki/Help:References" title="Help:References">
- Harmful effects: Possible minor side effects include allergic reactions and dizziness; only large dosages or long term usage can be toxic to the kidneys.
Ilex paraguariensis
- Maté (Ilex paraguariensis)
- Also called: yerba maté
- Consumed as a beverage. It is extremely popular in South America.
- Harmful effects: Non-caffeine-related side effects include an increased risk of mouth, esophageal, laryngeal, kidney, bladder, and lung cancer.<wiki/List_of_medicinal_plants#cite_note-mate-155"><wiki/List_of_medicinal_plants#cite_note-nyu-mate-156">The oral cancer associations may be due to the very high temperatures at which maté tea is traditionally drunk, but the associations with kidney, bladder, and lung cancer would not be temperature related.<wiki/List_of_medicinal_plants#cite_note-nyu-mate-156"> Caffeine-related side effects include insomnia, nervousness and restlessness, stomach upset, nausea and vomiting, increased heart rate and breathing, high blood pressure, headache, ringing in the ears, irregular heartbeats, slowed blood clotting, and worsened diarrhea.<wiki/List_of_medicinal_plants#cite_note-mate-155">
- Best remove it from your diet.
- Impila (Callilepsis laureola)
- A traditional Zulu remedy used for tapeworm, snakebites, infertility, whooping cough, and to kill maggots in cattle. It is also used as a disinfectant.<wiki/List_of_medicinal_plants#cite_note-135">
- It can cause fatal kidney and/or liver failure.<wiki/List_of_medicinal_plants#cite_note-136">