| TERM | GROUP | DEFINITION | |
|---|---|---|---|
| UMBEL | N | PLANTS | Pronunciation: Etymology: An inflorescence in which pedicels arise from the same point on the peduncle. |
| UMBO | N | ANIMALS | Pronunciation: Etymology: An umbo is the beak-like structure on a bivalve shell and the swollen part of the cone scale. |
| UNDULATING MEMBRANE | NP | PROTISTS | Pronunciation: Etymology: An undulating membrane is a an upraised portion of the cell membrane that is underlain by a flagellum to form a waving fin-like structure. |
| UNICELLULAR | ADJ | ANIMALS, PLANTS, PROTISTS, FUNGI, BACTERIA | Pronunciation: Etymology: A unicellular organism is made of a single cell. |
| UNILOCULAR ZOOSPORANGIUM (UNILOCULAR ZOOSPORANGIA) | NP | PROTISTS | Pronunciation: Etymology: A unilocular zoosporangium is a structure with a single opening in which meiosis occurs and zoospores develop. |
| UNIRAMOUS | ADJ | ANIMALS | Pronunciation: Etymology: Uniramous (adj.) means single-branched or unbranched. It usually refers to the unbranched leg of insects and other arthropods. |
| UNISEPTATE | ADJ | FUNGI | Pronunciation: Etymology: Having one septum or partion. |
| UNISTRATOSE | ADJ | PLANTS | Pronunciation: Etymology: Comprised of a single-cell layer, e.g. the leaves of most bryophytes. |
| UNITUNICATE | ADJ | FUNGI | Pronunciation: Etymology: Ascus with only one wall. |
| UREDIUM (UREDIA) | N | FUNGI | Pronunciation: Etymology: Structure in rusts that produces binucleated urideniospores. |
| URIDENIOSPORE | N | FUNGI | Pronunciation: Etymology: Microscopic structures at the end of hyphae in which fungi produce spores. |
| UROPOD | N | ANIMALS | Pronunciation: Etymology: Uropods are flatted lateral appendages on the next to last segment of crustaceans that are used for swimming. |
| UTERUS (UTERI OR UTERUSES) | N | ANIMALS | Pronunciation: Etymology: A uterus is part of a female reproductive system in which the egg is fertilized or implanted (in the case of mammals). |
