One Ring to rule them all, One Ring to find them, One Ring to bring them all and in the darkness bind them. - J.R.R. Tolkien
| term | definition | image |
| Two-angled | More or less flat in cross section, with an upper and lower surface. | |
| Typical | Stamen with distinct anther and filament with or without thecal appendages, as in Rhexia or Vacciniu... | |
| Umbel | An inflorescence in which individual flower stalks arise from a single point and are approximately o... | g-umbel1.png |
| Umbellet | The secondary umbel in a compound umbel | g-umbellet.png |
| Umbilicate | Depressed in the center | |
| Umbo | Projection, with or without spine or prickle, on the apophysis of the cone scale | |
| Umbonate | Round with a projection in center | g-umbonate.png |
| Umbraculate | Umbrella-shaped, as in Sarracenia | g-umbraculate-style.png |
| Umbraculiform | Umbrella-shaped | |
| Unarmed | Without a hook, prickle or other sharply pointed structure on the end of the cone scale. | |
| Uncinate | g-uncinate.png | |
| Unctuous | Slick, oily, slippery to touch | |
| Underground Stolon | A determinate, elongate, underground propagative stem with long internodes forming a bulb or tuber a... | g-underground-stolon.png |
| Understory | Trees, shrubs and other plants located beneath and in the shade of larger trees. | |
| Undulate | With the margin undulating or wavy in a vertical plane. (Compare with sinuate.) | g-undulate.png |
| Unguiculate | Clawed | g-unguiculate.png |
| Unicarpellous | With solitary, free carpel in gynoecium | g-unicarpellous.png |
| Unifoliolate | A structurally compound leaf with a single leaflet, making it appear simple, the compound nature of ... | g-unifoliolate.png |
| Unilateral | Flowers or other structures on one side of axis | |
| Unilocular | With a single interior compartment or locule. (Compare with multilocular.) | |
| Uninodal Shoot | Spring shoot developing from the terminal winter bud and producing only one internode with one whorl... | |
| Uniseriate | One-rowed; in one series | |
| Unisexual | Having functional reproductive structures of only one sex in the flower or cone. (Compare with bisex... | |
| Unknown | Relevant to taxon at hand but status not known; information unavailable. | |
| Unlobed | With no recesses or indentations in the margin, or with indentations extending less than 1/8 the dis... | |
| UPL | Upland. | |
| Urceolate | Urn-shaped | g-urceolate.png |
| Urent | With erect, usually long trichomes that produce irritation when touched. | g-urent.png |
| Utricle | A more or less small, dry fruit that does not split open at maturity (indehiscent), with a thin blad... | g-utricle.png |
| Vallecular Canal | A canal beneath a stem groove | |
| Valvate | With scales (usually two) meeting by the edges without overlapping. (Compare with imbricate.) | g-valvate.png |
| Valvular | Dehiscing through a pore covered by a flap of tissue. Valvular or Septifragal Capsule - One with val... | g-valvular.png |
| Variably serotinous | Having some cones that open when the seeds ripen and others that remain closed long after the seeds ... | |
| Variegated | The color disposed in various irregular, sinuous, spaces. | |
| Vascular bundle | A strand of conducting tissues and associated cells within a stem or connected structure. | |
| Vegetative | 1) Of, or relating to, the non-flowering parts of a plant. 2) Producing new plants asexually by the ... | |
| Vegetative Frond | Frond lacking sporangia | |
| Velum | The membranous flap covering the sporangium, as in Isoetes | |
| Velutinous | Covered with dense, straight, long and soft trichomes; pile-like | g-velutinous.png |
| Ventral | Pertaining to the surface nearest the axis; inner face of an organ; the upper surface of the leaf; a... | g-dorsal-ventral.png |
| Ventral Side | Top side or upper side of a perianth part. | g-dorsal-ventral.png |
| Ventricose | Inflated on one side near the middle | |
| Ventristipular | On ventral side of stipule | |
| Vermiform | Worm-shaped | |
| Vernal | Appearing in spring | |
| Verrucose | Warty | |
| Versatile | Dorsifixed but anther seemingly swinging free on the filament | |
| Verticillaster | A pair of axillary cymes arising from opposite leaves or bracts and forming a false whorl, as in man... | g-verticillaster.png |
| Verticillate | Three or more leaves or other structures per node | |
| Vespertine | With flowers opening in the evening or night; appearing or expanding in the evening | |
| term | definition | image |