April 08, 2009


Photographer: Dale Hugo
Summary Authors: Dale Hugo, Jim Foster

The photo above shows a soft maple tree weeping sap near my home in Arlington Heights, Illinois. I noticed that sap was excreting from this tree during a warm spell in early March 2009, but when temperatures plummeted soon afterwards (falling 45 degrees F or about 25 degrees C in 20 hours), this attention-getting sap stalactite formed. The tree is probably about the age of our sub-division, approximately 45 years. It’s about 3.5 feet (over 1 meter) in diameter at eye level. Note that the sap is colored by tannin from the bark that the sap-cicle is seeping over. Striations in the sap mass are reminiscent of "cave bacon," where soluble limestone moves over something like manganese oxide (MnO2), forming visible lines in the stalactites. My wife, Anne, and I have taken the same walking route through our neighborhood for over 30 years, in all sorts of weather conditions, but had never previously observed a sap-cicle.

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