| Rabdosia inflexa (Thunb.) Hara | MAKS1370, MAKS1371, MAKS2238, MAKS2239 |
| Rabdosia japonica (Burm.) Hara | MAKS1372 |
| Ranunculus japonicus Thunb. | MAKS0072, MAKS0073, MAKS0076, MAKS0321 |
| Ranunculus quelpaertensis (Lév.) Nakai | MAKS0070, MAKS0071, MAKS0074, MAKS0075 |
| Ranunculus sceleratus L. | MAKS0077 |
| Ranunculus ternatus Thunb. | MAKS0078, MAKS0079 |
| Raphanus sativus L. var. raphanistroides Makino | MAKS0190, MAKS0191, MAKS0192 |
| Raphiolepis indica (L.) Lindl. ex Ker var. umbellata (Thunb. ex Murray) Ohashi | MAKS1884 |
| Raphiolepis umbellata (Thunb.) Makino | MAKS1238 |
| Reineckea carnea (Andr.) Kunth | MAKS0790, MAKS2363, MAKS2362 |
| Retinispora koraiana Endlicher | MAKS1851, MAKS1852, MAKS1853 |
| Reynoutria japonica Houtt. | MAKS1474, MAKS1475, MAKS1476, MAKS0664, MAKS0662 |
| Reynoutria sachalinensis (Fr. Schm.) Nakai | MAKS0663 |
| Rhamnus costata Maxim. | MAKS1203 |
| Rhamnus crenata Siebold et Zucc. | MAKS0292, MAKS0336, MAKS1200, MAKS1251 |
| Rhamnus davurica Pallas var. nipponica Makino | MAKS1202, MAKS1250, MAKS1254 |
| Rhamnus japonica Maxim. var. decipiens Maxim. | MAKS0279, MAKS0293 |
| Rhamnus japonica Maxim. var. decipiens Maxim. ? | MAKS1253 |
| Rhamnus japonica Maxim. var. microphylla Hara | MAKS0294 |
| Rhapis humilis Bl. | MAKS0818, MAKS2119 |
| Rhododendron keiskei Miq. var. hypoglaucum Suto et Suzuki | MAKS1073 |
| Rhodomyrtus tomentosa (Ait.) Hassk. | MAKS2088 |
| Rhodotypos scandens (Thunb.) Makino | MAKS1921 |
| Rhoeo spathacea Stearn | MAKS0644, MAKS2386 |
| Rhus ambigua Lavall. ex Dipp. | MAKS0341 |
| Rhus japonica L. var. roxburghii (DC.) Rehder et Wils. | MAKS0353, MAKS1173 |
| Rhus succedanea L. | MAKS0338, MAKS0340, MAKS0350, MAKS1172, MAKS1246 |
| Rhus sylvestris Siebold et Zucc. | MAKS0348, MAKS0352 |
| Rhus sylvestris Siebold et Zucc.
Rhus trichocarpa Miq. | MAKS1280 |
| Rhus trichocarpa Miq. | MAKS0339, MAKS0342, MAKS0349 |
| Rhus verniciflua Stockes | MAKS0343, MAKS0347, MAKS1174, MAKS0306 |
| Rhynchosia volubilis Lour. | MAKS1161 |
| Rhynchospermum verticillatum Reinw. | MAKS1021, MAKS1022 |
| Rhynchospora rubra (Lour.) Makino | MAKS2554 |
| Ribes ambiguum Maxim. | MAKS0910, MAKS0911, MAKS1949 |
| Ribes fasciculatum Siebold et Zucc. | MAKS0912, MAKS0913, MAKS0914, MAKS1952 |
| Ribes sinanense F. Maekawa | MAKS0908 |
| Ribes uva-crispa L. | MAKS1950 |
| Ricinus communis L. ? | MAKS1514 |
| Rodgersia podophylla A. Gray | MAKS1985 |
| Rohdea japonica (Thunb.) Roth | MAKS2178 |
| Rosa hirtula (Regel) Nakai | MAKS1900 |
| Rosa rugosa Thunb. | MAKS1899 |
| Rosa sp. | MAKS1902, MAKS1903, MAKS1905 |
| Rosa uchiyamana Makino | MAKS1904 |
| Rosmarinus officinalis L. | MAKS1373 |
| Rotala indica (Willd.) Koehne var. uliginosa (Miq.) Koehne | MAKS2080 |
| Rubia argyi (Lév.) Hara | MAKS1997, MAKS0814 |
| Rubus hirsutus Thunb. | MAKS1914 |
| Rubus microphyllus L. fil. | MAKS1915 |
| Rubus palmatus Thunb. var. palmatus | MAKS1919 |
| Rubus parvifolius L. | MAKS1916 |
| Rubus trifidus Thunb. | MAKS1920 |
| Rubus yabei Lév. et Van't. var. marmoratus (Lév. et Van't.) Ohwi | MAKS1917 |
| Rumex | MAKS1438, MAKS1440 |
| Rumex crispus L. | MAKS0646 |
| Rumex madaio Makino | MAKS1437, MAKS1439, MAKS0647 |
| Rumex sp. | MAKS0648 |
