The giants of the plant world. Indeed, the biggest living things on the planet are towering trees. When fully grown, these trees have a true presence, soaring to dizzying heights. Standing at the foot of such a specimen one has to lean back and crane the head to see the top, 30m or even 40m above, as high as a 10-storey building. Such trees may be in their third century, having been planted during the collection craze of the 19th century. More than anything else, this era of establishment of arboreta was given momentum by the discovery of these giants in temperate areas of the world, especially in western North America, including redwoods, Sitka spruce, western hemlock, Douglas fir and western red cedar. The western red cedar, Thuja plicata, from western North America, makes a conical tree of bright green to over 20m, though often less. As it ages the side branches arch outwards, sometimes touching the ground. In turn, these develop so the mature tree (at about 100 years) has several majestic, curving trunks. Its foliage is scented with resin and can be detected some distance away on a warm day.