July 11, 2014: Erv's Field Notes #69

 Deb Lewis leads a prairie plant interpretive walk. 7/12/12 (Kevin Kane)

Thursday, July 10, 2014. Sunny, slight southerly breeze, 78 degrees F.

Deb Lewis, Curator of the ISU Ada Hayden Herbarium, led an informative interpretive field program of the reconstructed prairie near the Harrison Street Parking Lot. Central Iowa is in the range of the Tallgrass Prairie Region that formerly extended eastward as far as Ohio. Deb explained the key identifying characteristics of the major plant families in the prairie and discussed representative species of these families that were present along the trails.

The daisy or aster family (Asteraceae) is represented by the sunflowers and coneflowers that have complex flowering heads with many ray flowers and disc flowers. The saw-toothed sunflower is just starting to bloom. The species is names after their leaves which have serrated edges, hence the scientific name of the species, grossaserratus. The flowering heads of this species are showing evidence of MLO, also known as microplasm disease. Many of the flowering heads appear stunted with abnormal leaf-like structures growing within the disk flowers. This family includes three species that are in the same genus (Silphium) and all three are growing nearby. These are the compass plant, cup-plant, and rosinweed. The compass plant gets its name from the tendency of its flat, deeply lobed leaves to orient themselves on a North-South axis. It is said that the Early Settlers used it to guide their way. Even though these three species all have yellow-ray flowers with a central disk, they are still easily identifiable - particularly by their leaves, which are all distinct.
Nearby were several plants known as rattlesnake master. This species is in the carrot family (Apiaceae) which is well represented in prairies. The leaves and stems are relatively stiff and the edges of the leaves sharply lobed with spine-like edges that resemble the familiar yucca plant. Hence, the species name yuccafolium.

The tick trefoil is a common member of the bean or legume family (Fabaceae). The tick trefoil is common in the Hayden Park prairies but is just beginning to bloom. It has a pink flower and produces a small sticky seed known as beggar’s lice or beggar’s ticks that will attach themselves to clothing or hair. This adaptation allows the seed to be spread far and wide.

Here is the list of the plants that Deb identified and commented on during our brief walk. Sawtooth sunflower, compass plant, cup plant, rosinweed, rattlesnake master, tick trefoil, Canada goldenrod, mountain mint, purple prairie clover, dogbane, culver’s root, beebalm, yellow sweet clover, bird’s foot trefoil, hoary vervain, black-eyed susan, curled dock, smooth dock, side-oats grama, crown vetch, white sweet clover, gray-headed coneflower, butterfly milkweed, prairie dropseed, Illinois bundleflower, blue grama, cinquefoil, prairie sage, false sunflower (oxeye), horse nettle, common ragweed, giant ragweed, switch grass, yarrow, and elderberry.

Most of the grasses have not started blooming yet but in late summer and fall big bluestem, Indian grass, little bluestem and switch grass will become dominant.
The next program will be Thursday, July 17 at 6:00 pm and will be about damselflies and dragonflies. Meet at the shelter on the north side.

Erv Klaas