Donkey
Donkeys can interbreed with other members of the family Equidae, and are commonly interbred with horses. The hybrid between a jack and a mare is a mule, valued as a working and riding animal in many countries. Some large donkey breeds such as the Asino di Martina Franca, the Baudet de Poitou and the Mammoth Jack are raised only for mule production. The hybrid between a stallion and a jenny is a hinny, and is less common. Like other inter-species hybrids, mules and hinnies are usually sterile. Donkeys can also breed with zebras in which the offspring is called a zonkey (among other names).
Equisetaceae
All living horsetails are placed in the genus "Equisetum". But there are some fossil species that are not assignable to the modern genus. "Equisetites" is a "wastebin taxon" uniting all sorts of large horsetails from the Mesozoic; it is almost certainly paraphyletic and would probably warrant being subsumed in "Equisetum". But while some of the species placed there are likely to be ancestral to the modern horsetails, there have been reports of secondary growth in other "Equisetites", and these probably represent a distinct and now-extinct horsetail lineage. "Equicalastrobus" is the name given to fossil horsetail strobili, which probably mostly or completely belong to the (sterile) plants placed in "Equisetites".