Kalmar “genus” a ilmin halitta tana nufin wani matsayi na haraji da aka yi amfani da shi wajen rarraba rayayyun halittu, wanda ya haɗa da rukunin nau’in halittu waɗanda ke da alaƙa ta kud da kud dangane da tarihin juyin halitta da halayensu na zahiri. "Physostegia" wani nau'in tsire-tsire ne na furanni a cikin dangin Lamiaceae, wanda ya haɗa da kusan nau'in 10 na herbaceous perennials 'yan asalin Arewacin Amirka. Ana kiran waɗannan tsire-tsire da tsire-tsire masu biyayya saboda kowane furanni na iya juya su ta hanyoyi daban-daban ba tare da karya tushen tushe ba. halittar Physostegia.