Bush. A low woody perennial plant with branches at or near ground level

Bustard. Large birds (Aves) of numerous species found chiefly in Africa but also in Europe and Asia (India), chiefly terrestrial but are powerful fliers; related to rails and cranes.

Butterfly. An insect (Lepidoptera) with four large wings, usually completely covered with scales, distinguished from moth by the clubbed antennae.

Buttress root. An asymmetrically thickened prop root, found at the base of certain trees.

Bypass vessel. A blood vessel which joins arteries and veins, thus bypassing capillaries. Constriction or dilation regulates the blood flow through the capillaries.