During bloom time lindens are easy to distinguish by their aroma and the clusters of small yellow flowers which resemble open tulips. After the flowers bloom and the seed, or nutlet, forms the linden can still be identified by the remains of the cyme, or flower clusters, and the bracts hanging along the branches. While still on the tree, bracts and cymes look like an extra, lighter green frill hanging below the leaves.
The term bract was new to me, although on investigation, most of us are probably familiar with them in some form and think of them as “flower petals.” Instead they are specialized structures which protect the actual flowers of various species. Often, as in the case of poinsettias and dogwoods, we mistake the colored bracts for the flowers.
Most of my resources say little about the cymes and bracts of the lindens. One website did talk about the bracts on lime trees, the British name for lindens. An interesting tidbit is that along with the flowers, bracts are harvested to make linden tea, which is known to help digestive disorders. It is also used as a sleep aid. The bracts alone may be made into a “beauty lotion” for cleansing the skin
Later in the year you have a clue you are under a linden when you find thin yellow leaves, which are actually bracts, under a tree. This year at least, these seemed to fall and scatter sooner than the actual leaves, but even when they are mixed with other leaves, they are distinctive in their thin, oval shape, rather like a tongue.
There are a number of other linden trees on the City Park Arboretum tour. Most of them are either hybrids or cultivars. I can’t begin to tell a Greenspire Linden from a Redmond, although the first is a Tilia cordata and the latter is Tilia americana. According to Michael Dirr and Keith Warren in The Tree Book: Superior Selections for Landscapes, Streetscapes, and Gardens, each of these two trees, along with the many other cultivars, has its uses. The other cultivars found on the Arboretum tour are listed below with information from The Tree Book mentioned above. Numbers correspond to those on the Arboretum map.
C126 Tilia americana Sentry is narrower than most other versions and may have some resistance to Japanese beetles.
C171 Tilia americana Redmond (C171) is said to be more urban tolerant that other lindens.
C148 Tilia cordata Greenspire has the best pyramidal shape.
C177 Tilia cordata Norlin is both a fast grower and cold hardy.
A83 Tilia x flavescens Glenleven is a hybrid between the American linden and the littleleaf linden and is known at the fastest growing linden hybrid.
E22 Tilia cordata Prestige. It seems little is written about this variety but it may be pollution resistant.
C178 Tilia x flavescens Dropmore The Dropmore linden is another hybrid which is viable to zone 2.
C 149 Tilia cordata Fairview is said to have larger leaves.