Close up of Japanese larch needles and cones in fall .
WHAT ’ S IN IT FOR THE TREE ? Sometimes people call us with worries about a dying tree that turns out to be a perfectly healthy larch or other deciduous conifer ( see sidebar ) dropping its needles for the cool season .
How does being deciduous benefit a larch ? Larches grow in cold , low-nutrient environments , and being deciduous helps them avoid damage to foliage by extreme winter weather . It also helps the trees to conserve resources during the least productive part of the year . For highelevation species such as western and subalpine larches , heavy snow loads are less likely to damage branches , compared to trees that retain their foliage in winter . ( The elevation range of western larch is about 1600 to 7000 feet , while that of subalpine larch is 5900 to 7900 feet . You are unlikely to see subalpine larch in Seattle because it does not thrive in mild winter climates .)
Larches are very fire resistant , and part of this has to do with the needles , which have a high water content ( and so are less flammable ) compared to those of evergreen conifers . Shedding needles may also be a defense against overwintering insects . And because larches don ’ t need to invest a lot of time and energy manufacturing chemicals such as lignins and toxins to make their leaves tough or durable — and resistant to herbivory — they have a high level of photosynthetic efficiency .
LARCH LORE Western larch is the largest larch species when growing in its native range . Its straight , upright growth makes it useful for lumber . Early 19th-century explorer David Thompson noticed 200-foot-tall larches on the Kootenai River ( northern Montana and Idaho ) and observed that they would be useful as ship masts . If he had asked the local Kutenai tribe , they could have informed him that the wood is used for the center pole in their ceremonial Sun Dance .
Frank A . Lang ’ s essay on western larch in the “ Oregon Encyclopedia ” ( oregonencyclopedia . org ) draws a connection between the name “ larch ” ( possibly from the Celtic “ lar ,” meaning “ fat ”) and the copious quantities of resin the tree holds — a polysaccharide called arabinogalactan . Native American tribes have a long history of using the sap and resin as candy or as a gum to soothe sore throats and heal cuts . ( Pliny the Elder noticed the resinous gum , too , in Old World larches : “ The wood of this tree is far more valuable , being unimpaired by time , and proof against all decay … Resin flows from this wood in still greater quantities ; it is of the color of honey , more viscous than the other varieties , and never turns hard .”)
16 v Washington Park Arboretum Bulletin