Keel (bird anatomy) Keel (bird anatomy) A keel or carina (plural carinae) in bird anatomy is an extension of the sternum (breastbone) which runs axially along the midline of the sternum and extends outward, perpendicular to the plane of the ribs. The keel provides an anchor to which a bird's wing muscles attach, thereby providing adequate leverage for flight. Keels do not exist on all birds; in particular, some flightless birds lack a keel structure. Historically, the presence or absence of a pronounced keel structure was used as a broad classification of birds into two orders: Carinatae (from "carina", "keel"), having a pronounced
Plant anatomy Pflanzen", describing microscopic studies of plant tissues. In 1813 a Swiss botanist, Augustin Pyrame de Candolle, published "Théorie élémentaire de la botanique", in which he argued that plant anatomy, not physiology, ought to be the sole basis for plant classification. Using a scientific basis, he established structural criteria for defining and separating plant genera. In 1830, Franz Meyen published "Phytotomie", the first comprehensive review of plant anatomy. In 1838 German botanist Matthias Jakob Schleiden, published "Contributions to Phytogenesis", stating, "the lower plants all consist of one cell, while the higher plants are composed of (many) individual cells" thus confirming and