Covering eighty-three acres, Holliday Park borders Indiana's White River, which originates near the state's eastern edge and snakes southwest, taking a circuitous route through Indianapolis and finally emptying into the Wabash River. The heavily wooded park is crisscrossed by trails, some with boardwalks that help the hiker negotiate the wetter zones. When the White River is at normal stage, it is bordered by a narrow, muddy beach. Wetland plants grow in shallow water nearby, while the inland floodplain is covered with tree species that can tolerate periodic flooding. Farther off, low hills are home to a drier, upland forest containing a wide variety of trees, shrubs, and wildflowers.
Most botanists believe it is distantly related to verbenas.
It has pink blooms and, for a plant that is often less than a foot tall, relatively large leaves. The seed capsules, shaped somewhat like parrots, lie fiat against the stem and point straight down. Several natural springs on the hill slopes yield clear, cool water that trickles in rivulets toward the river. And at the convergence of the rivulets is an extensive wetland known as a fen, a boglike habitat more frequently found in northern Indiana, northern Illinois, Michigan, and Canada. Whereas bogs are acidic, the water in a fen is basic, owing to the presence of bedrock composed of limestone or dolomite.