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Tree Flowers

Dirty trees 

American sycamore, sweetgum, buckeye,
Siberian elm, and silver maple

There is a magnificent American sycamore (Platanus occidentalis) growing alongside Henderson Avenue just west of its intersection with North High St. in Columbus. American sycamores, whose girth can be greater than that any other eastern North American tree (early settlers sometimes lived in hollow sycamores) manage to persist in urban areas, remnants of the day when these neighborhoods were not so urban. Urban foresters nowadays frown upon having such "forest giants" as these, or tulip-tree, or silver maple, in the city. Sycamores are well known for having bark that peels off, exposing lighter, almost white, bark beneath.   

sycamore shed bark

American sycamore July 18, 2006, Columbus OH.

sycamore bark

Shed bark of American sycamore July 18, 2006, Columbus OH.  The large piece looks like a face.

In fruit, Amercian sycamore produces inch-wide globe-shaped clusters of one-seeded fruits (achenes) tipped by a cluster of tawny hairs that enable them to drift in the wind. Starting in late winter, and extending into early spring, the fruits break apart and masses of them accumulate near the trees.  

creamy violet

Hairy achenes of American sycamore, along with flat samaras of American elm, mid-May, Orange Rd and Rte 315, Delaware OH.

The early American botanist William Bartram correctly pointed out that Sweetgum (Liquidambar styraciflua, family Hamamelidacae) is a tree that you would not want to dance beneath barefoot! Sweetgum is well known as the source of spherical spiny clusters of capsules, one of which is shown below along with a lot more sweetgum bud scales that fell on a 1994 Honda Civic Del Sol in late April..

sweetgum achenes and bud scales

Sweetgum cluster of capsules and bud scales, April 26, 2006.

Seetgum is monoecious, i.e., it produces unisexual flowers, with both types found on on the same tree. After they have released their pollen, branched clusters of male flower heads fall to the ground.

sweetgum staminate flowers

Sweetgum staminate flower clusters, May 2, 2008, Columbus, OH

The beloved Ohio buckeye, Aesculus glabra (Family Hippocastanaceae) can be quite the litterbug too. Many plants, including buckeye, produce many more flowers than fruits, and then initiate many more fruits than they finally end up maturing. Aborted flowers and fruits are scattered annually on buckeye-lined Powell Road in Powell, Ohio.

buckeye flowers on road

Road adorned with fallen buckeye flowers, May 10, 2006, Powell, Ohio

buckeye flowers on the ground

 Fallen buckeye flowers, May 10, 2006, Powell, Ohio

buckeye fruits on road

Sidewalk adorned with immature buckeye fruits, June 23, 2006.

buckeye fruits close

Immature buckeye fruits, June 23, 2006, Powell, Ohio.

In the American midwest, just when it seems summer is finally upon us, it starts snowing! The "snow" is the wind-blown seeds of the aptly-named eastern cottonwood (Populus deltoides, family Salicaceae) that sometimes forms drifts as shown here along Lake Erie in Mentor, OH.

cottonwood cotton

Drifted windblown seeds of eastern cottonwood, June 2002, Mentor, Ashtabula County, OH.

Elms produce wind-disseminated one-seeded fruits (samaras). On the campus of Ohio State University in Columbus, there are many Siberian elm (Ulmus pumila, family Ulmaceae) trees planted perhaps as a subsitute for American elms lost to Dutch elm disease. They are prolific fruit producers, and they collect along the curbs in parking lots near the trees, as shown here in front of Aronoff Laboratory.

Siberian elm fruit parking lot

Siberian elm fruits along curb at edge of parking lot, OSU Columbus campus, May 15, 2008.

In a more natural setting by the Olentangy River, the native red elm (also called "slippery elm"), Ulmus rubra, is fairly common. Beneath a large tree, an inch-thick mat of fruits covered the edge of the road bordering Delawanda Park in Columbus. Notice that these fruits are larger than those of American elm (shown above with American sycamore), and they have smoth, not hairy, edges. 

red elm fruits

Red elm fruits on the ground, May 6, 2006.

Speaking of samaras, the most well-known ones are the double "helicopters" of maples. Silver maple (Acer saccharinum, family Aceraceae) fruits early and abundantly.

silver maple sidewalk
Silver maple samaras at edge of sidewalk, May 10, 2008

samaras of silver maple

Silver maple samaras, May 10, 2008.

samara s in the grass

Silver maple samara in grass, in a seemingly ideal position for germination, May 10, 2008.

"Dirty trees" might be a nuisance at times, but that's a small price to pay for the fascinating glimpse they provide into the world of plant adaptations. Carbon sequestration is good too!