A Grammatical Dictionary of Botanical Latin

Thapsus,-i (s.f.II), also Thapsos,-i (s.f.II) [cf. Gk. thapsos (s.f.II): fustic, Rhus Cotinus, used for dyeing yellow, brought from the island of Thapsos (Liddell & Scott).

Thapsia (s.f.I): a small genus of poisonous plants, the deadly carrots (Apiaceae). Thapsia garganica [> L. Thapsia,-ae (s.f.I): = G. thapsia, a poisonous shrub, Thapsia Asclepium, also thapsos (Lewis & Short); Thapsia,-ae (s.f.I): So named from the first species being discovered in the Isle of Thapsus. Apiaceae (Paxton).

NOTE: garganus,-i (s.m.II): “a mountain ridge in Apulia on which storms are frequent;” adj. garganus,-a,-um (adj.A): Gargan, of or belonging to Garganus” (Lewis & Short).

Thapsium, Nuttall. From the Isle of Thapsus, which gave the name to the Thapsia of the ancients; in allusion to its affinity with that genus. Apiaceae. (Paxton).

Thapsus,-i (s.f.II), or Thapsos, -i (s.f.II), = Gk. thapsos [note gender]: “a peninsula and city in Sicily, now Magnisi; a city in Africa Propria, famed for Caesar’s victory over the partisans of Pompey, now Baltah” (Lewis & Short).

“Verbascum thapsus was first described by Carl Linnaeus in his 1753 Species Plantarum. The specifi epithet thapsus had been first used by Theophrastus (as Θάψος, Thapsos) for an unspecified herb from the Ancient Greek settlement of Thapsos, near modern Syracuse, Sicily,though it is often assimilated to the ancient Tunisian city of Thapsus” (Wikipedia July 20, 2018).