Tuliptrees, or tulip poplars, line the western half of University Avenue in Berkeley. They’re not universally popular poplars, mostly because they’re prone to aphid infestations and the aphids’ sticky excretions drip onto everything below, attract soot, and nourish sooty black molds. Too bad, because it’s a noble tree with roots in American history.
Besides not being popular, they aren’t actually poplars. They’re magnolia relatives, Liriodendron tulipifera, “the lily tree that bears tulips,” fellow members of one of the most ancient families of flowering plants. They’ve been known by a bewildering variety of names: Rakiock, American tulipwood, canoe wood, carney wood, whitewood, blue poplar, white poplar, yellow poplar, hickory poplar, tulip poplar, tulip magnolia, tuliptree, popple, and probably a few others. Lumbermen, biologists, folklorists, and cabinetmakers drive each other crazy with this sort of thing.
Their flowers do resemble tulips in that they’re upright and a bit conical or cup-shaped. Janet Lembke, in her charming book Shake Them ‘Simmons Down, describes them as “large greeny-white cups lined with touches of saffron and redgold.” They really are subtly lovely; the pity is that they’re usually held well above our range of sight, on these high-trimmed urban street trees. You might see some after they’ve dried out and fallen in winter; they look a little like papery, skinny pine cones.
The trees themselves manage to maintain some of their native shape even under the deforming stresses of city life. The incessant wind off the bay sometimes makes them a bit lopsided, though. Their tops have a gracious loose spread that turns to a widely conical top, like an enormous slow green flame. Their branches are resilient enough to give them a graceful dancing motion in the wind, where they have been allowed the space to move. Their trunks are graceful, too, straight and smoothly tapered, covered with smooth-ish light brown bark. They’re fast growers but unlike most such trees, are long-lived, sometimes to 300 years in their home range.
Tuliptrees are native farther east in North America, from Florida to New England and Ontario, west to southern Michigan and eastern Arkansas. They get—or used to get—huge on the southern coastal plain and in the Appalachians; old stories mention trees big enough to make a dugout canoe that could easily carry 20 men and their gear. It was supposed to be a tuliptree that Daniel Boone hollowed out into a 60-foot canoe to ferry his family and homestead necessities down the Ohio River into Spanish territory when he left Kentucky.
The genus Liriodendron has only one other species, and that one’s in China, L. chinense. This odd distribution happens in several ancient species groups, including magnolias, that seem to have evolved in one area and been sundered by continental drift.
The tree excited Europeans who first met it in America, and they catalogued its uses as well as its beauty. The wood is light but tough, easily worked, though by some accounts it tends to absorb and lose moisture easily and thus swell and shrink if it isn’t sealed. This doesn’t seem to hurt its reputation as a canoe wood—one of the first names Europeans called it, as it was used and recommended for that purpose to the Walter Raleigh expedition by indigenous Americans. Thomas Jefferson was fond of it and named his country estate Poplar Forest for the wild ones surrounding it, and planted more as he landscaped the grounds. He sent lots of its seeds to Europe—and he was far from the first to do so, as it’s mentioned as a garden tree there as early as 1687.
Tuliptrees can grow seriously large, but I don’t suppose we’ll ever see a street tree get as big as the one reported in 1709, one 10 feet in diameter “wherein a lusty Man had his Bed and Household Furniture, and liv’d in it.” Another associated marvel we probably won’t see with our city dwellers is their mycorrhizal associate, the morel mushroom. Then again, given the wide reach of a tree’s roots—roughly in a circle whose radius is one and a half the tree’s height, is the rule of thumb—it might prove fruitful to look around any nearby patches of dirt or lawn in the rainy season.