Libocedrus decurrens

Koch/Tamarack Larix occidentalis Nutt./ Western larch Libocedrus decurrens Torn/ Incense cedar Picea engelmanni Parry ex Engelm./Engelman spruce Picea glauca (Moench) Voss/ White spruce... 

Cupressaceae Chamaecyparis lawsoniana Juniperus horizontalis Libocedrus decurrens Pinaceae Abies concolor... 

Zavarin E, Anderson A B 1955 Extractive components from incence-cedar heartwood Libocedrus decurrens Torrey). I. Occurrence of carvacrol, hydrothymoquinone and thymo-quinone. J Org Chem 20 82-88... 

Durability of heartwood is dependent on the kinds and concentration of extractives present, their chemical stability, and their resistance to microbial inactivation. Many tree species (e.g., Madurapomifera or Robiniapseudoacacia) contain only one or two toxic compounds, often in very small quantities, yet the wood is extremely durable (45, 54). In other species a number of similar toxic compounds may occur together (Libocedrus decurrens (5)), or toxic compounds of a very different chemical nature may be present in the heartwood of a single species (stilbenes and ellagitannins in Eucalyptus sideroxylon (23). In either case, the combination of compounds acts additively or perhaps even synergistically to produce an inhibitory environment. 

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