| Macrantha | S, R 48 |
| Macrocarpa | R 36 |
| Madame Louis Aureau | R 49 |
| Madame Maurice Lassailly | R ± 48 |
| Magnifica | R 60 |
| Magnifica | S 62 |
| Maisie Lowe | R 48 |
| Majestic | R 48 |
| Malvina | L 24 |
| Ma Mie | R 24 |
| Mandraliscae | L 24 |
| Maori King | R 25 |
| M. A. Porter | R ± 50 |
| Mareschal Ney | R ± 48 |
| Marian Lapham | R 24 |
| Marie Louise Caillat | R 49 |
| Marine Wave | R 44 |
| Marocain | R 40 |
| Marquita | R 47 |
| Marsouin | S 24 |
| Mary Barnett | R 24 |
| Mary E. Nicholls | R 48 |
| Mary Geddes | R 49 |
| Mary Vernon | R ± 48 |
| Matterhorn | R 49 |
| Matula | R 48 |
| Mauna Loa | R 48 |
| May Day | R 48 |
| Maygold | R 45 |
| Melitza | R 47 |
| Mephistopheles | L 24 |
| Michel-Ange | S 49 |
| Midgard | R 24 |
| Midwest | R 24 |
| Midwest Gem | R 51 |
| Ming Yellow | R 48 |
| Minnie Colquitt | R ± 48 |
| Miobelle | R ± 48 |
| Miranda | R 24 |
| Miriam | S 36 |
| Miss California | R 49 |
| Miss Muffett | R 45 |
| Missouri | R 49 |
| Miss Willmott | R 51 |
| Mistopink | R 31 |
| Mlle. Schwartz | S 36 |
| Mme. Chereau | L, R 24 |
| Mme. Chobaut | R 24 |
| Mme. Savouillan | R 45, 47 |
| Modiste | R 48 |
| Mohrmead | R 46 |
| Mohrson | R 46 |
| Molière | S 47 |
| Monadnock | R 50 |
| Monsignor | S 24 |
| Monterey | R 48 |
| Moongleam | R 40 |
| Moonlight | R 47 |
| Morning Light | R & M 39 |
| Morning Splendor | R 48 |
| Morphee | R 24 |
| Mount Cloud | R 48 |
| Mount Washington | R 48 |
| Mozo | R 22 |
| Mrs. George Darwin | R 24 |
| Mrs. G. L. Gibson | R 48 |
| Mrs. H. M. White | R 24 |
| Mrs. Horace Darwin | L 24 |
| Mrs. Marion Cran | R 24 |
| Mrs. Tinley | R 24 |
| Mrs. Valerie West | R ± 48 |
| Mrs. Walter Brewster | S 36 |
| Mt. McKinley | R 47 |
| Mulberry Kose | R ± 48 |
| Multicolor | S 24 |
| Murillo | S 24 |
| Mustapha | R 22 |
| Myomy | R 22 |