Equidae
Equidae (sometimes known as the horse family) is the taxonomic family of horses and related animals, including the extant horses, donkeys, and zebras, and many other species known only from fossils. All extant species are in the genus "Equus". Equidae belongs to the order Perissodactyla, which includes the extant tapirs and rhinoceros, and several extinct families.
Equisetum
The genus "Equisetum" as a whole, while concentrated in the non-tropical northern hemisphere, is near-cosmopolitan, being absent only from Antarctica, though they are not known to be native to Australia, New Zealand nor the islands of the Pacific. They are most common in northern North America (Canada and the northernmost United States), where the genus is represented by nine species ("arvense", "fluviatile", "palustre", "pratense", "sylvaticum", "hyemale", "laevigatum", "scirpoides", and "variegatum"). Only four ("bogotense", "giganteum", "myriochaetum", and "ramosissimum") of the fifteen species are known to be native south of the Equator. They are perennial plants, herbaceous and dying back in winter as most temperate species, or evergreen as most tropical species and the temperate species rough horsetail ("E. hyemale"), branched horsetail ("E. ramosissimum"), dwarf horsetail ("E. scirpoides") and variegated horsetail ("E. variegatum"). They typically grow 0.2–1.5 m tall, though the "giant horsetails" are recorded to grow as high as 2.5 m (northern giant horsetail, "E. telmateia"), 5 m (southern giant horsetail, "E. giganteum") or 8 m (Mexican giant horsetail, "E. myriochaetum"), and allegedly even more.