| Common name | Botanical name |
| 1. Lablab | Lablab vulgaris |
| 2. Labrador Tea | Ledum latifolium |
| 3. Labrador tea, Northern | Ledum decumbens Ledum palustre ssp. decumbens |
| 4. Labrador, Glandular-leaved | Ledum glandulosum |
| 5. Laburnum | Cytisus laburnum |
| 6. Laburnum, Purple | Cytisus purpurascens |
| 7. Lace Cap Hydrangea | Hydrangea macrophylla |
| 8. Lacebark Elm | Ulmus parvifolia |
| 9. Lace-flower, Blue | Didiscus caeruleus 'Heavenly Blue' |
| 10. Lachnanthes | Lachnanthes tinctoria |
| 11. Lacquer tree, Japanese | Rhus vernicifera |
| 12. Lady Fern | Athyrium filix-femina |
| 13. Lady?s finger or Okra | Hibiscus esculentus Abelmoschus esculentus |
| 14. Ladybell, Common | Adenophora liliifolia |
| 15. Lady's Bedstraw | Galium verum |
| 16. Lady's Mantle | Alchemilla mollis Alchemilla vulgaris Alchemilla xanthochlora |
| 17. Lady's Mantle, Alpine | Alchemilla alpina |
| 18. Lady's Slipper Orchid | Cypripedium calceolus Cypripedium cordigerum |
| 19. Lady's Smock | Cardamine pratensis |
| 20. Lady's Tresses | Spiranthes autumnalis Spiranthes australis |
| 21. Ladyslipper, Mountain | Cypripedium montanum |
| 22. Lakooch | Artocarpus gomezianus |
| 23. Lambang | Aleurites moluccana |
| 24. Lamb's Tail | Chiastophyllum oppositifolium |
| 25. Lanhoa | Olea fragrans |
| 26. Lantana | Lantana camara Lantana indica |
| 27. Lantern Flower, Parasol Flower, Parachute Flower | Ceropegia beddomei Ceropegia decaisneana Ceropegia maculata Ceropegia metziana Ceropegia pusilla Ceropegia spiralis Ceropegia thwaitesii |
| 28. Lantern, Japanese | Hibiscus schizopetalus |
| 29. Larch | Larix decidua |
| 30. Larch, Western | Larix occidentalis |
| 31. Large-flowered Trillium | Trillium grandiflorum |
| 32. Large-leaved Aster | Aster macrophyllus |
| 33. Larger Bittercress | Cardamine amara |
| 34. Larkspur | Consolida ajacis Consolida orientalis |
| 35. Latern Tree, Chilean | Crinodendron hookerianum |
| 36. Laurel | Terminalia crenulata |
| 37. Laurel, Bog, Western | Kalmia microphylla ssp. occidentalis Kalmia polifolia |
| 38. Laurel, Mountain | Kalmia latifolia |
| 39. Laurel, Sheep's | Kalmia angustifolia |
| 40. Laurel, Swamp | Kalmia glauca |
| 41. Laurel, White | Magnolia virginiana |
| 42. Laurel-leaved Rock Rose | Cistus laurifolius |
| 43. Lavender Cotton | Santolina chamaecyparissus |
| 44. Lavender of Dauphine | Lavandula delphinensis |
| 45. Lavender Thyme | Thymus thracicus |
| 46. Lavender, Bastard | Lavandula angustifolia x latifolia |
| 47. Lavender, Desert | Hyptis emoryi |
| 48. Lavender, French | Lavandula stoechas |
| 49. Lavender, Hidcote or Jean Davis Lavender or Lady Lavender or Munstead Lavender or English Lavender or Twickle Purple Lavender or Rosea Lavender | Lavandula angustifolia |
| 50. Lavender, Provence | Lavandula x intermedia |
| 51. Lavender, Spanish | Lavandula dentata |
| 52. Lavender, Spike | Lavandula latifolia Lavandula officinalis var. spica |
| 53. Lavender, Sweet | Lavandula heterophylla |
| 54. Lavender, True | Lavandula officinalis |
| 55. Lavender, Woolly | Lavandula lanata |
| 56. Laver Seaweed | Porphyra umbilicalis |
| 57. Lawson Cypress | Chamaecyparis lawsoniana |
| 58. Leadplant | Amorpha canescens |
| 59. Leather Flower | Clematis viorna |
| 60. Leatherleaf Mahonia | Mahonia bealei |
| 61. Leatherwood UK | Cyrilla racemiflora |
| 62. Leaved Hibiscus, Red | Hibiscus acetosella |
| 63. Lechugilla | Agave lechugilla |
| 64. Leek | Allium porrum |
| 65. Leek, Wild | Allium tricoccum |
| 66. Lemon | Citrus limon |
| 67. Lemon grass | Cymbopogon citratus Cymbopogon flexuosus |
| 68. Lemon Hyssop, Mexican | Agastache mexicana |
| 69. Lemon Licorice Mint | Agastache breviflora |
| 70. Lemon Marigold | Tagetes tenuifolia |
| 71. Lemon Thyme | Thymus x citriodorus |
| 72. Lemon Verbena | Aloysia triphylla |
| 73. Lemon, Cedrat | Citrus medica cedra |
| 74. Lemon, Java | Citrus javanica |
| 75. Lemon, Pear | Citrus limetta |
| 76. Lemon, Pearl | Citrus margarita |
| 77. Lemon, Sweet | Citrus lumia |
| 78. Lemon, Water | Passiflora laurifolia |
| 79. Lemonberry | Rhus integrifolia |
| 80. Lemon-scented Iron Bark | Eucalyptus staigeriana |
| 81. Lentil | Ervum lens |
| 82. Leopard Tree | Caesalpinia ferrea |
| 83. Leopard's Bane | Doronicum caucasicum Doronicum plantagineum |
| 84. Leopard's Bane, Austrian | Doronicum austriacum |
| 85. Leopard's Bane, Showy | Doronicum cordatum |
| 86. Lesser Burdock | Arctium minus |
| 87. Lesser Celandine | Ranunculus ficaria |
| 88. Lesser Galangal | Alpinia officinarum |
| 89. Lesser Scabious | Scabiosa columbaria |
| 90. Lesser Sea Lavender | Limonium gougetianum |
| 91. Lesser Spearwort | Ranunculus flammula |
| 92. Lettuce, Garden | Lactuca sativa |
| 93. Lettuce, Prickly | Lactuca serriola |
| 94. Lettuce, Romaine | Lactuca sativa var. longifolia |
| 95. Lettuce, Tall | Lactuca canadensis |
| 96. Lettuce, Wild | Lactuca virosa |
| 97. Leucas | Leucas aspera |
| 98. Leyland Cypress | X Cupressocyparis leylandii |
| 99. Lichen | Candelariella vitellina |
| 100. Licorice, Silver | Helichrysum petiolare |
| 101. Life Root | Senecio aureus |
| 102. Lilac Californian | Ceanothus arboreus Ceanothus azurea Ceanothus impressus Ceanothus thyrsiflorus |
| 103. Lilacs | Syringa vulgaris |
| 104. Lilies, Swamp | Lilium pardalinum |
| 105. Lily of The Valley | Convallaria majalis |
| 106. Lily, African | Agapanthus africanus |
| 107. Lily, Chaparral | Lilium rubescens |
| 108. Lily, Columbia | Lilium columbianum |
| 109. Lily, Easter | Lilium longiflorum |
| 110. Lily, Formosa | Lilium formosanum |
| 111. Lily, Giant | Cardiocrinum giganteum |
| 112. Lily, Madonna | Lilium candidum |
| 113. Lily, Nepal | Lilium nepalensis |
| 114. Lily, Panther | Lilium canadense |
| 115. Lily, Peruvian | Alstroemeria aurea Alstroemeria haemantha Alstroemeria ligtu Alstroemeria ligtu x haemantha |
| 116. Lily, Royal | Lilium regale |
| 117. Lily, Straw-coloured Turk's Cap | Lilium pyrenaicum |
| 118. Lily, Tiger | Lilium tigrinum |
| 119. Lily, Toad | Tricyrtis hirta |
| 120. Lily, Turk's Cap | Lilium superbum |
| 121. Lily, Turk's Cap, Purple | Lilium martagon |
| 122. Lily, Turk's Cap, Yellow | Lilium pomponium verum |
| 123. Lime | Tilia europaea |
| 124. Lime Fruit | Citrus aurantiifolia |
| 125. Lime Mint | Mentha x piperita var. citrata |
| 126. Lime Tree | Tilia platyphyllos Tilia x vulgaris |
| 127. Lime, Common | Tilia vulgaris |
| 128. Limno, Asian | Limnophila aromatica |
| 129. Limnopoa | Limnopoa meeboldii |
| 130. Linden American | Tilia americana |
| 131. Lingonberry | Vaccinium vitis-idaea |
| 132. Linseed | Linum Usitatissimum |
| 133. Lion's Ear | Leonotis leonurus Leonotis nepetaefolia |
| 134. Lippia | Phyla scaberrina |
| 135. Liquorice | Glycorrhiza glabra |
| 136. Liquorice, American | Glycorrhiza lepidota |
| 137. Liquorice, Asian | Glycorrhiza uralensis |
| 138. Liquorice, Russian | Glycorrhiza echinata Glycorrhiza glandulifera |
| 139. Liriope | Liriope muscari |
| 140. Litchi | Dimocarpus litchi Litchi chinensis Nephelium litchi Scytalia chinensis |
| 141. Litmus | Roccella tinctoria |
| 142. Little Elephant's Head | Pedicularis attollens |
| 143. Littleleaf Linden | Tilia cordata |
| 144. Liver lily | Iris setosa |
| 145. Liverwort American | Hepatica nobilis |
| 146. Liverwort, English | Peltigera canina |
| 147. Lobelia, Butterfly | Lobelia |
| 148. Lobelia, Downy | Lobelia puberula |
| 149. Lobelia, Fountains | Lobelia erinus |
| 150. Lobelia, Great | Lobelia siphilitica |
| 151. Lobelia, Red | Lobelia cardinalis |
| 152. Locust, Black | Robinia pseudacacia |
| 153. Lodolcea | Lodolcea seychellarum |
| 154. Logwood | Haematoxylon campeachianum |
| 155. Logwood, West Indian | Ceanothus chloroxylon |
| 156. Lomatium, Fernleaf | Lomatium dissectum |
| 157. Lomatium, Pestle | Lomatium nudicaule |
| 158. London Planetree | Platanus x acerifolia |
| 159. Long Papper, Pipli | Piper longum |
| 160. Long pepper | Chavica roxburghii Piper longum Piper officinarum |
| 161. Longan | Dimocarpus longana Euphoria longana Nephelium longana |
| 162. Long-leaved Bear's Breech | Acanthus balcanicus |
| 163. Long-rooted Garlic | Allium victorialis |
| 164. Loose-headed Chinese Cabb | Brassica pekinensis var. |
| 165. Loosestrife, Bog | Lysimachia barystachys |
| 166. Loosestrife, Fringed | Lysimachia ciliata |
| 167. Loosestrife, Garden | Lysimachia punctata |
| 168. Loosestrife, Prairie | Lysimachia quadrifolia |
| 169. Loosestrife, Purple | Lythrum salicaria |
| 170. Loosestrife, Veined | Lysimachia menoricensis |
| 171. Loosestrife, White | Lysimachia ephemerum |
| 172. Loosestrife, Yellow | Lysimachia vulgaris |
| 173. Loquat | Crataegus bibas Eriobotrya japonica Mespilus japonica Photinia japonica |
| 174. Loranthus | Loranthus |
| 175. Lotus | Nelumbium nelumbo Nelumbium nuciferum Nelumbium speciosum |
| 176. Lotus Flower, Desert | Lotus rigidus |
| 177. Lovage | Levisticum officinale |
| 178. Lovage, Celery Leaf | Ligusticum apiifolium |
| 179. Lovage, Gray's | Ligusticum grayi |
| 180. Lovage, Hulten's | Ligusticum hultenii |
| 181. Lovage, Scotch | Ligusticum scoticum |
| 182. Lovage, Water | Oenanthe fistulosa |
| 183. Love in a puff or Heart seed | Cardiospermum halicacabum |
| 184. Love Lies Bleeding | Amaranthus caudatus |
| 185. Loveapple | Solanum aculeatissimum |
| 186. Love-in-a-mist / Nigella | Nigella damascena |
| 187. Low Cluster Danesblood Be | Campanula glomerata var. acaulis |
| 188. Low Gumweed | Grindelia nana |
| 189. Lucerne, Tree | Cytisus prolifer |
| 190. Luffa | Luffa aegyptiaca Luffa cylindrica |
| 191. Luffa, Wild | Luffa astorii |
| 192. Lungwort | Sticta pulmonaria |
| 193. Lungwort, Common | Pulmonaria officinalis |
| 194. Lungwort, Cowslip | Pulmonaria angustifolia |
| 195. Lungwort, Hairy | Pulmonaria mollissima |
| 196. Lupin, Siberian | Thermopsis lupinoides |
| 197. Lupin, White | Lupinus albus |
| 198. Lupin, Yellow | Lupinus luteus |
| 199. Lupine, Tree | Lupinus arboreus |