Fennel is used as a food plant by the larvae of some Lepidoptera species including in its native range the mouse moth and the Old-World swallowtail. Where it has been introduced in North America it may be used by the anise swallowtail. The word "fennel" developed from the Middle English "fenel" or "fenyl". This came from the Old English "fenol" or "finol", which in turn came from the Latin "feniculum" or "foeniculum", the diminutive of "fenum" or "faenum", meaning "hay". The Latin word for the plant was "ferula", which is now used as the genus name of a related plant. The
Flavour (particle physics) violated by weak interactions. Therefore, such flavour quantum numbers are not of great use. A separate quantum number for each generation is more useful: electronic lepton number (+1 for electrons and electron neutrinos), muonic lepton number (+1 for muons and muon neutrinos), and tauonic lepton number (+1 for tau leptons and tau neutrinos). However, even these numbers are not absolutely conserved, as neutrinos of different generations can mix; that is, a neutrino of one flavour can transform into another flavour. The strength of such mixings is specified by a matrix called the Pontecorvo–Maki–Nakagawa–Sakata matrix (PMNS matrix). All quarks carry a