The warts are natural outgrowths of the bark and the pink color is due to a harmless lichen. Hackberries are in the Elm family and have small, reddish-brown edible drupes. Commercial examples of drupes are peaches, plums, and cherries.
Further along the trail is an excellent demonstration tree. It supports the harmless Virginia Creeper (Parthenocissus quinquefolia) on the left and the insidious Poison Ivy (Rhus toxicodendron or Toxicodendron radicans) on the right. Notice that the Virginia Creeper has five or more leaflets per leaf while the Poison Ivy has only three.
Poison Ivy climbs by aerial rootlets. All parts of the plant are toxic, so avoid the roots too. Avoid any vine with rootlets like this until you find out for sure what the leaves look like.
The path here has been cut up and rutted by the passage of mountain bikes. Bikers are encouraged to stick to the grassy trails and avoid the bare paths. This rutted path in the flood plain has not been permanently damaged by erosion because the water rises into it rather than running through it.
However, the paths in the upland woods along the small drainages are especially susceptible to erosion and ought to be avoided by mountain bikers. The bikes pull soil down on the descent into the crossings and push soil down when ascending the other side. This eventually destroys plant roots that hold the soil together and makes the area even more erosion prone. These upland drainages are also the habitat of Spiranthes parksii, an endangered species.
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This collection of ruts was at the side of a large permanent mud puddle in the middle of the path. There were two of these on this stretch of the path, lying in wait for the unwary. (The city has since filled the puddles in. We sort of miss them--they were natural.)
The second puddle was more treacherous. Lying in its middle was the end of a branch that was handy to cling to until it broke off and fell in. There was usually a betting pool on who would fall in next.
Back at the right of way, there is a place where water crosses the opening. It used to be shallow and wide, but in recent years has become deep and narrow. One more example of the effects of erosion.
