Last updated October 1, 2009
| Name | Family | Nativity |
| Laelia anceps | Orchidaceae | Mexico |
| Laelia rubescens | Orchidaceae | Mexico, Cen America |
| Laeliocattleya cv. Callistoglossa | Orchidaceae | |
| Laeliocattleya cv. Elizabeth ‘Sparkling Burgundy’ | Orchidaceae | |
| Lagunaria patersonia | Malvaceae | Australia |
| Lampranthus deltoides | Aizoaceae | South Africa(W. Cape Province) |
| Lantana montevidensis | Verbenaceae | Argentina |
| Lasiocereus rupicola | Cactaceae | Peru(Cajamarca) |
| Lastreopsis effusa | Dryopteridaceae | American Tropics |
| Lastreopsis microsora ssp. pentangularis | Polypodiaceae | Australia |
| Lavandula dentata | Lamiaceae | Mediterranean |
| Lavandula dentata v. candicans | Lamiaceae | Europe |
| Lavandula pinnata v. buchii | Lamiaceae | Spain(Canary Islands) |
| Lavandula stoechas | Lamiaceae | Mediterranean |
| Lavandula stoechas cv. Otto Quast | Lamiaceae | |
| Lavatera cv. Purissima | Malvaceae | |
| Leonotus leonuris | Lamiaceae | South Africa |
| Lepechinia hastata | Lamiaceae | Hawaii, Mtns. of Baja Mexico |
| Lepidozamia hopei | Zamiaceae | Australia |
| Lepidozamia peroffskyana | Zamiaceae | Australia(SE Queensland) |
| Lepismium bolivianum | Cactaceae | Bolivia(La Paz) |
| Lepismium cruciforme v. | Cactaceae | Brazil, Argentina |
| Lepismium lumbricoides | Cactaceae | Uruguay, N Argentina |
| Lepismium warmingianum | Cactaceae | Brazil, E Paraguy, N Argentina |
| Leptocereus quadricostatus | Cactaceae | Puerto Rico |
| Leptochilus ellipticus | Polypodiaceae | Japan, Korea, China, SE Asia |
| Leptospermum brevipes | Myrtaceae | E Australia |
| Leptospermum laevigatum | Myrtaceae | E & S Australia |
| Leptospermum scoparium cultivar | Myrtaceae | |
| Leucadendron argenteum | Proteaceae | South Africa(W. Cape Province) |
| Leucadendron cv. Jester | Proteaceae | |
| Leucophyta brownii | Asteraceae | Australia |
| Leymus arenarius cv. Glaucus | Poaceae | |
| Leymus cv. Canyon Prince | Poaceae | |
| Leymus glaucus | Poaceae | North America |
| Ligustrum japonicum | Oleaceae | Japan, Korea |
| Lilium hybrids | Liliaceae | |
| Limonium perezii | Plumbaginaceae | (Spain)Canary Islands |
| Limonium sp. | Plumbaginaceae | |
| Linospadix monostachya | Arecaceae | E Australia |
| Liquidambar styraciflua | Hamamelidaceae | Conn. to Florida & Cen America |
| Liquidambar styraciflua | Hamamelidaceae | E.US through C. Amer. |
| Liquidambar styraciflua cv. Burgundy | Hamamelidaceae | |
| Liriope muscari | Convallariaceae | Japan, China |
| Liriope spicata cv. | Convallariaceae | |
| Lithodora diffusa cv. Heavenly Blue | Boraginaceae | |
| Livistona australis | Arecaceae | E Australia |
| Livistona chinensis | Arecaceae | China |
| Livistona decipiens | Arecaceae | Australia(Queensland) |
| Livistona drudei | Arecaceae | Australia(Queensland) |
| Livistona rigida | Arecaceae | Australia |
| Livistona saribus | Arecaceae | SE Asia |
| Livistona sp. | Arecaceae | Australia |
| Lobelia erinus hybrid | Campanulaceae | |
| Lobelia fulgens | Campanulaceae | Mexico |
| Lobelia fulgens | Campanulaceae | Texas, Mexico |
| Lobelia laxiflora v. angustifolia | Campanulaceae | Mexico |
| Lobularia maritima | Brassicaceae | |
| Lobularia maritima | Brassicaceae | Mediterranean |
| Lomandra longifolia | Xanthorrhoeaceae | E & S Australia |
| Lonchocarpus capassa | Papilionaceae | South Africa |
| Lophophora diffusa | Cactaceae | Mexico |
| Lophophora williamsii | Cactaceae | Cen & N Mexico |
| Lophosoria quadripinnata | Lophosoriaceae | Cen & S America |
| Loropetalum chinense | Hamamelidaceae | Himalayas, China, Japan |
| Loropetalum chinense v. rubrum cv. Razzleberri | Hamamelidaceae | |
| Ludwigia peploides | Onagraceae | N & S America |
| Ludwigia repens | Onagraceae | North America |
| Ludwigia sedoides | Onagraceae | |
| Luehea divaricata | Tiliaceae | Brazil |
| Lygodium japonicum | Schizaeaceae | |
| Lysimachia nummularia cv. Aurea | Primulaceae | |
| Lytocaryum weddellianum | Arecaceae | Brazil |
