As in other mammals, thermoregulation is an important aspect of human homeostasis. Most body heat is generated in the deep organs, especially the liver, brain, and heart, and in contraction of skeletal muscles. Humans have been able to adapt to a great diversity of climates, including hot humid and hot arid.
Japanese knotweed is a perennial weed, producing tall canes, up to 2.1m (7ft) in height during the summer. The canes have characteristic purple flecks, and produce branches from nodes along its length. These branches support shovel-shaped leaves.
In Japan, fiddleheads of flowering fern (Osmunda japonica), known as zenmai (è), as well as those of the ostrich fern (Matteuccia struthiopteris), known as kogomi (ã³ã´ã), are commonly eaten in springtime. Fiddleheads in Japan are considered sansai, or wild vegetables.