These species are resistant to decay in their natural state, due to high levels of organic chemicals called "extractives", mainly polyphenols, providing them antimicrobial properties. Extractives are chemicals that are deposited in the heartwood of certain tree species as they convert sapwood to heartwood; they are present in both parts though. Huon pine ("Lagarostrobos franklinii"), merbau ("Intsia bijuga"), ironbark ("Eucalyptus" spp.), totara ("Podocarpus totara"), puriri ("Vitex lucens"), kauri ("Agathis australis"), and many cypresses, such as coast redwood ("Sequoia sempervirens") and western red cedar ("Thuja plicata"), fall in this category. However, many of these species tend to be prohibitively expensive for general construction applications.