Ma'anar ƙamus na kalmar "tsaron ƙarni" yana nufin wani nau'in tsiro mai ɗanɗano daga dangin agave, yawanci ana samunsa a yankuna masu bushewa na Arewa da Kudancin Amurka. Ana kiran shukar ne saboda an yi imani sau ɗaya kawai a kowace shekara 100 kafin ta mutu, kodayake a zahiri, yawanci tana fure bayan shekaru 10 zuwa 30. An san tsire-tsire na karni da girman girmansa, tare da manyan tsire-tsire sau da yawa suna kaiwa tsayin ƙafa 20 kuma suna samar da tsayin fure mai tsayi wanda zai iya girma har zuwa ƙafa 30. Hakanan ana amfani da shuka don dalilai daban-daban, gami da tushen abinci, fiber, da barasa.