| ROOTAGE | A developed system of the underground parts of a plant (7) |
| ROOT | Origins of the underground part of a plant |
| CORMS | What are the underground parts of crocuses and cyclamens? (5) |
| CAVERN | The underground parts of vinca vernalis |
| BULBOUS | Shaped like the underground part of e.g. tulip (7) |
| TAPROOT | Main underground part of a plant (7) |
| STOMATA | Minute epidermal pores in the green parts of a plant that control the inward and outward passage of water vapour and other gases (7) |
| ROOTLET | Small underground part of a plant |
| RADICLE | Grows into the shoot system of the seed (7) |
| COMTISM | Philosophical system of the founder of Positivism |
| ROOTS | Underground parts of a plant (5) |
| MADEIRA | Admire a developed EU island (7) |
| RHIZOME | Underground part of plant, one unknown in river refuge (7) |
| TUBEROUS | Having fleshy, thickened underground parts of a stem or rhizome (8) |
| HARRIET | Tubman of the Underground Railroad |
| BULBS | Underground parts of plants such as the crocus, dahlia, winter aconite, chionodoxa (glory-of-the-snow) snowdrop and narcissus (5) |
| TUBER | A thickened underground part of a stem, e.g. in a potato (5) |
| ALMAGEST | A work on astronomy, compiled by Ptolemy in the 2nd century AD, containing a description of the geocentric system of the universe and a star catalogue |
| BULB | Underground part of a tulip or onion |
| AERIALROOTS | Parts of a plant, normally found underground, but which here grow from a stem above ground (6,5) |
