Life Along Expressways

     I have driven on expressways in southeastern Pennsylvania many times over the years and noticed a variety of outstanding plants growing on what had been disturbed soil on the banks and shoulders of those roadways.  But today I decided to tally the plant species of interest to me as I drove by them.
All these plants are successional species that pioneer disturbed soil, holding it in place with their roots and enriching it with their fallen leaves and other parts that decay into the ground.  And they grow unimpeded by mowing or plowing in many stretches of those roadsides, providing food and cover for mice, small birds, hawks, skunks and many other kinds of wildlife.
     Four species of trees are outstanding on those disturbed, but recovering roadsides, including red junipers, Bradford pears, staghorn sumacs and ailanthus.  Junipers are a kind of native conifer that has evergreen needles but strange cones.  Their masses of pale-blue cones are berry-like.  But if examined closely, one can see the few faint scales on them.  A variety of birds, including starlings, cedar waxwings, American robins, eastern bluebirds and others, feed on those cones through winter, adding their feathered beauties to those of the junipers.  Those birds digest the pulp of the cones, but pass the seeds in their droppings, thus spreading junipers across the countryside.
     Alien Bradford pear trees escaped captivity as an ornamental planting on lawns and along city streets by birds eating their fruits and passing their seeds far and wide.  Groves of this species grow in abandoned places, such as roadsides.  This type of tree has striking red and maroon foliage in November, helping to make it an attractive tree.  And it provides abundant food for wildlife of many kinds, including rodents, birds, opossums and other species.  Red-tailed hawks and American kestrels perch in trees to watch the roadsides for vulnerable rodents to catch and eat.
     Staghorn sumacs are small, native trees that have red leaves by September and into October, adding more beauty to the roadsides.  On top of their twigs, they have attractive, pyramid-shaped clusters of red, velvety seeds that are again consumed by rodents and small birds, birds that, again, spread the inner seeds around in their droppings.
     Ailanthus trees are from Asia, but were planted in big city streets in the United States because their leaves can resist air pollution.  However, because female ailanthus have orange seeds that float away on the wind, this tree has spread across the countryside, including along expressways where they are usually ignored.
     It's interesting to me that many low spots along the expressway shoulders that are always wet or moist have wetland plants growing in them, most notably patches of cattails, phragmites, and crack willow trees.  Cattail and phragmites seed heads are quite attractive, particularly in winter when they are more noticeable.  Phragmites seed heads are fluffy-looking, especially when sunlight shines through them.  Cattails provide cover for nesting red-winged blackbirds and song sparrows.  And muskrats eat cattail roots and stems and use them to make their homes.  Mallard ducks sometimes land on roadside puddles to ingest aquatic vegetation. 
     Broom grass and foxtail grass are attractive along roadsides, particularly in winter when they are most noticeable.  Clumps of broom grass are orange-yellow and seem to glow in sunlight.  Patches of foxtail grass are pale-yellow and have obvious seed heads in winter that are loaded with seeds and do look like foxes' tails.  The grass seeds, and those of roadside common milkweeds, goldenrods, asters, evening primrose and other seed-producing, wild plants feed mice and seed-eating birds such as sparrows and finches all winter.
     And there are many stretches of expressway shoulders and banks that have been planted to short grass that is regularly mowed.  Though we might think those manicured parts of roadsides are a waste of space to wildlife, they are not.  Cottontail rabbits, wood chucks, and, in places, white-tailed deer come out of roadside thickets to graze on that grass, within yards of the expressway.  Groups of starlings and American robins drop to those roadside lawns to eat invertebrates out of the short grass.  And flocks of honking Canada geese land on those roadside lawns to eat the grass itself.  All that is well for the wildlife and us, as long as the critters stay out of the fast-moving traffic.    
     When riding along an expressway, watch for the many wild plants and animals that can be seen along them.  they can make a ride more interesting.