Zannichel'lia: named for Giovanni Girolamo Zannichelli (Gian Girolamo, Giovanni Gerolamo) (1662-1729), Italian botanist, physician and pharmacist. He was born in Venice. After his first training in Modena, he went to further studies in Venice and in 1684 was at the Collegio degli Speziali, a well-known educational institution of pharmacy. Beginning in 1686 he built a successful apothecary business in Venice, and in 1702 was awarded a medical degree. He made many trips to explore the natural history around the Adriatic Sea, building an important natural history cabinet in Venice. Among his works are Istoria delle plante. He was in contact with prestigious scholars of the time, such as the famous Florentine botanist Pier Andrea Micheli, naturalist Antonio Vallisnieri, Italian anatomist Giovanni Battista Morgagni, and Veronese pharmacist Bartolomeo Martini. In 1701, Zannichelli published Remediorum Chymicorum, a compilation of more than 100 remedies of animal, vegetable and mineral components. Aside from botany, he was also very interested in paleontology and minerology. In 1710 he made excursions to the mountains of Vicenza and Verona, collecting numerous fossil shells, plants and fish. A year later, he presented these findings together with other pieces from Portugal, Switzerland, Greece, Savoy and other provinces of Italy for the first time publicly. This was followed in 1712 by another exhibition in which the focus was on crystals, stones and minerals, which came from Saxony and other parts of Germany, from Bohemia, Hungary, Norway, from the islands of Corsica and Elba and from Tyrol and Italy. He was the leading scholar of his time of the flora of the Venice region. The genus Zannichellia was published in 1753 by Carl Linnaeus and is commonly called horned pondweed.

Zanthoxy'lum: yellow wood. Stearn says "from the Greek xanthos, "yellow," and xylon, "wood," for the color of the heartwood in some species." Common names for this genus include prickly ash, Hercules' club, and toothache tree. Wikipedia says "It is technically misspelled, as the 'z' should be 'x', but botanical nomenclature does not allow for spelling corrections." It also says "It refers to a yellow dye made from the roots of some species," which may or may not be correct. The genus Zanthoxylum was published by Carl Linnaeus in 1753 and is called prickly-ash or toothache tree.

Ze'a: Stearn says "from the Greek name for another cereal. The crop is widely cultivated in the tropical and temperate zones from sea level to about 12,000'. It is the staple graini in Mexico and Central America, and southern Africa. In the United States about 90% of the crop is fed to animals." Gledhill suggests that it may have been the ancient Greek name for spelt. The best-known species is Z. mays (variously called maize, corn, or Indian corn), one of the most important crops for human societies throughout much of the world. The four wild species are commonly known as teosintes and are native to Mesoamerica. Teosintes are considered the mother of corn. Interestingly, there was a Columbian journalist, botanist, diplomat, politician, and statesman named Francisco Antonio Zea (1770-1822) who served as Vice President of Colombia under then President Simón Bolívar, and it might have been thought that Zea was named for him, but he does not appear to have had anything to do with the genus Zea because it was published by Carl Linnaeus in 1753 before he was born. Zea has been commonly called corn or maize.

Zeno'bia: named for Septimia Zenobia (AD c. 240-274), Queen of the Palmyrene Empire in Syria. She was the second wife of the ruler of the city Palmyra and then became Queen when Odaenathus became king. After Odaenathus' assassination, Zenobia became the regent of her son Vaballathus and held de facto power throughout his reign, ruling over an area that included Anatolia and Egypt which was called the Roman East. Although nominally subordinate to Rome, at some point she declared her son emperor and herself empress and attempted to secede from Rome. Heavy fighting ensued and she was captured by Emperor Aurelian and exiled to Rome where she spent the remainder of her life. She had maintained a stable administration and governed over a multicultural, multiethnic empire and fostered an intellectual environment in her court, which was open to scholars and philosophers. She was tolerant toward her subjects and protected religious minorities. In addition to her Aramaic mother tongue, she was fluent in Egyptian, Greek and Latin. There is much about her history that is disputed and not confirmed, but that she was a real person is not in doubt. The genus Zenobia was published by David Don in 1834 and is called zenobia or honeycup.

Zephyran'thes: from Greek zephyros, "the west wind," and anthos, "a flower," supposedly because it is a native of the western hemisphere. Wikipedia says somewhat dubiously, "The name is derived from Zephyrus, the Greek god of the west wind, and anthos, meaning flower, referring to the slender stalks." The genus was published by William Herbert in 1821 and is called atamasco-lily, zephyr-lily and rain-lily.

Zigaden'us: derived from the Greek zygon, "yoke," and aden, "gland," referring to the pair of glands on each tepal of the type species. The genus Zigadenus was published by André Michaux in 1803 and is called death-camas. FNA adds that the common name “death camas” is derived from the illness or death resulting from ingesting bulbs of Zigadenus that were mistaken for the edible ones of Camassia, an unrelated plant.

Ziza'nia: from the Greek zizanion, an ancient name for a wild weedy grain that typically grew among wheat crops. Wikipedia adds this: "Wild rice, also called manoomin, mnomen, Canada rice, Indian rice, or water oats, is any of four species of grasses that form the genus Zizania, and the grain that can be harvested from them. The grain was historically gathered and eaten in both North America and China, but eaten less in China,where the plant's stem is used as a vegetable. Wild rice is not directly related to domesticated rice (Oryza sativa and Oryza glaberrima), although they are close cousins, all belonging to the tribe Oryzeae." The genus Zizania was published by Carl Linnaeus in 1753 and is called wild rice.

Zizaniop'sis: resembling genus Zizania. Th genus Zizaniopsis was published by Johann Christoph Döll and Paul Friedrich August Ascherson in 1871 and is commonly called giant cutgrass.

Ziz'ia: named for Johann Baptist Ziz (1779-1829), a German botanist who was born in Mainz in the Rhineland. The genus Zizia, called golden-alexander, was published by Wilhelm Daniel Joseph Koch in 1824.

Zorn'ia: named for Johannes Zorn (1739-1799), German pharmacist, botanist and botanical illustrator. He was born in Kempten, Germany, and after his studies in pharmacy, he became an apothecary in his hometown. He was passionate about the flora of the New World and made extensive trips across Europe to collect medicinal plants. Between 1779 and 1790 he published six volumes of Icones plantarum medicinalium in Nuremberg in which he illustrated and described over 600 medicinal plants. The genus Zornia was published by Johann Friedrich Gmelin in 1792 and is simply called zornia.

zosteriformis: having the shape of or resembling the genus Zostera.

Zoy'sia: named for Baron Karl von Zoys (Karl Zois Edelstein) (1756-1800), Austrian botanist and plant collector. The genus Zoysia was published by Carl Ludwig Willdenow in 1801.