Last updated October 1, 2009
| Name | Family | Nativity |
| Iberis sempervirens | Brassicacaea | |
| Iberis sempervirens cv. Snow White | Brassicaceae | |
| Iberis sp. | Brassicaceae | |
| Ibervillea sonorae v. peninsularis | Cucurbitaceae | SW North America |
| Ilex aquifolium cv. | Aquifoliaceae | |
| Ilex cornuta cv. Burfordii | Aquifoliaceae | |
| Ilex cornuta cv. Rotunda | Aquifoliaceae | |
| Ilex crenata cv. Convexa | Aquifoliaceae | |
| Ilex opaca cv. Rotundifolia | Aquifoliaceae | |
| Ilex pernyi | Aquifoliaceae | Cen China |
| Ilex sp. | Aquifoliaceae | |
| Impatiens balfourii | Balsaminaceae | W. Himalaya |
| Impatiens balsamina cv. Pink | Balsaminaceae | |
| Impatiens balsamina cv. Red | Balsaminaceae | |
| Impatiens balsamina cv. Violet | Balsaminaceae | |
| Impatiens cv. | Balsaminaceae | |
| Impatiens cv. Orange | Balsaminaceae | |
| Impatiens sodenii | Balsaminaceae | E Tropical Africa |
| Impatiens sp. | Balsaminaceae | Bali |
| Indigofera natalensis | Fabaceae | South Africa |
| Iochroma coccinea | Solanaceae | South American Tropics |
| Iochroma cyaneum | Solanaceae | South America |
| Ipomoea platense | Convolvulaceae | |
| Ipomoea sp. | Convolvulaceae | |
| Iris cv. Frequent Flyer | Iridaceae | |
| Iris cv. Lotusland | Iridaceae | |
| Iris kaempferi | Iridaceae | Japan |
| Iris sp. | Iridaceae | |
| Isolatocereus dumortieri | Cactaceae | Cen Mexico |
| Isopogon formosus | Proteaceae | Western Australia |
| Itea ilicifolia | Iteaceae | China |
