Horse outward similarity is an unreliable measure of relatedness. Besides the horse, there are six other species of genus "Equus" in the Equidae family. These are the ass or donkey, "Equus asinus"; the mountain zebra, "Equus zebra"; plains zebra, "Equus quagga"; Grévy's zebra, "Equus grevyi"; the kiang, "Equus kiang"; and the onager, "Equus hemionus". Horses can crossbreed with other members of their genus. The most common hybrid is the mule, a cross between a "jack" (male donkey) and a mare. A related hybrid, a hinny, is a cross between a stallion and a jenny (female donkey). Other hybrids include the zorse,
Tourist (horse) was a late developing horse who won back-to-back Breeders' Cup Classics, and is known for siring offspring that also tend to develop later in their career and are best at a distance of a mile and up. Tiznow is the most important modern descendant of Man o' War in the direct male line – the sire line traces back to the Godolphin Arabian. Tourist's dam, Unbridled Melody by Unbridled's Song, comes from a strong female family that has produced multiple stakes winners in recent generations. Unbridled Melody produced five named foals, four of them stakes winners. Tourist has been described