Poaceae groups, using the C3 and C4 photosynthetic pathways for carbon fixation. The C4 grasses have a photosynthetic pathway, linked to specialized Kranz leaf anatomy, which allows for increased water use efficiency, rendering them better adapted to hot, arid environments and those lacking in carbon dioxide. The C3 grasses are referred to as "cool-season" grasses, while the C4 plants are considered "warm-season" grasses. The grass family is one of the most widely distributed and abundant groups of plants on Earth. Grasses are found on every continent, including Antarctica with the presence of Antarctic hair grass on the Antarctic Peninsula. Grasses are
I Should Have Known Better solo) and thus draws a line under a significant period of their early music. The song's middle sixteen section features George Harrison's brand new Rickenbacker 360/12 12-string guitar. The mono and stereo versions have slightly different harmonica introductions. In the stereo version, the harmonica drops out briefly. Also, a noticeably clumsy and audible tape edit is heard during the second chorus between "You're gonna say you love me too, oh," and "And when I ask you to be mine." In the UK, "I Should Have Known Better" appeared on "A Hard Day's Night" and was released on 10 July 1964.