With the approach of winter, the needles of bald cypress trees – delicate as the fronds of a fern – turn the color of rust and flame as the trees withdraw their chlorophyll. Despite being a conifer, the bald cypress is deciduous.

Shedding leaves each autumn and beginning over again each spring is a survival strategy. It requires a considerable investment of a tree’s energy to grow new leaves. It pays off only it costs more to maintain leaves year-round.

Trees typically abandon their leaves to conserve water, especially in cold climates where leaves can become desiccated by frost. It may require substantial amounts of moisture to keep the leaves hydrated, putting the entire tree at risk. Dropping its leaves when the weather turns cold, a deciduous tree minimizes the risk.

The average winter temperature on the coastal plain of North Carolina is in the mid-30s. That hardly seems a sufficient threat for a cypress tree to violate the rules of its own phylum and become a deciduous conifer. Why do it? Why become an outlaw?

That’s a good question. I spent hours rephrasing Google searches, even wading into the obtuse nether regions of Google Scholar. I still don’t have a good answer.

Apparently, it’s one of those botanical mysteries. Like the knees of bald cypress.