21 June 2021

The air smells honey-sweet in Pittsburgh this month because the basswoods (lindens) are in bloom.

American basswood (Tilia americana) is a native tree in eastern North America with close relatives across the Northern Hemisphere. In Europe Tilia species are called linden trees. In the British Isles they are “lime trees” though not at all related to lime fruit. (Aha! Lindens are the “avenue of lime trees” in English novels.)

Basswoods grow naturally in the forest (left below) but are often used in landscaping. You can recognize them by their large size and distinctive teardrop shape (right below).

In June you can find them by smell, which is how I discovered the basswood at top in Schenley Park on 12 June.

Bees find them, too, so here’s a word to the wise. Never ever spray pesticide on linden (basswood) trees in bloom. A pesticide company did that in Oregon in June 2013 and killed 50,000 bees, the largest native bee kill on record.

p.s. Sometimes a linden tree drops “sap” on everything beneath it. But it isn’t sap. It’s excretion from an infestation of linden aphids (Eucallipterus tiliae) that are sucking the Tilia leaves. The Toronto Master Gardeners website explains what to do. Again, do not spray the tree while it’s in bloom!

(photos by Kate St. John, plus Vern Wilkins and Richard Webb via bugwood.org)