The tamarack is unusual because it is the only conifer native to Minnesota that is not evergreen. The photos below show how local tamaracks have changed color from September to October prior to dropping all their needles.
A disadvantage for deciduous trees is that they must expend considerable resources to make new leaves each year. During summer these leaves are very effective in capturing solar energy for the tree, but they are shed in fall because they are not suitable for winter. In contrast the leaves (needles) of evergreen trees are not as good at capturing energy in the summer, but they are made for winter survival and last several years before needing to be replaced. Plus, evergreen needles capture solar energy year-round.
Tamaracks have developed a survival strategy that is a mix of deciduous and evergreen traits. Like the evergreen conifers, tamaracks have needles. However its needles are “cheaply made” — thin, flimsy and not meant for winter survival. The open architecture of the tamarack tree maximizes the sun exposure for each needle, which somewhat compensates for the fact that the needles are only available to capture energy in the summer. Dropping needles is also advantageous to the tamarack because it helps the tree avoid structural damage caused by clinging heavy snow.
Another North American conifer that drops its leaves each fall is the Bald Cypress, the state tree of Louisiana. It is an interesting coincidence that both of these deciduous conifers prefer swampy environments. Perhaps a plentiful water supply is also key to their survival strategy?
Tamarack trees near Laporte, Minnesota are still green on September 23. Their characteristic scraggly form is evident in the picture on the left above.
The picture on the right above shows a tamarack beginning to turn from green to yellow. This tree is near the Shingobee River on the Paul Bunyan Trail, October 9.
Tamaracks that have turned yellow in fall are very striking trees. These tamaracks photographed on October 18 are near Williams Lake in Hubbard County, Minnesota.