Monday, May 31, 2021

Plant Profile: Wild Geranium

Several pink-flowering stems of wild geranium.

Wild geranium (Geranium maculatum) is a native, herbaceous perennial of open woods and woodland edges. It begins blooming in May, about the same time as Trillium, with loose clusters of pink to lavender flowers at the ends of hairy stems. The plant is also called wild cranesbill or storksbill for the long, beak-like capsules produced after flowering.

In the flower on the left, the inner ring of anthers is releasing pollen.
The stigma is not yet mature. On the right, the anthers are past maturity
and the curled, five-parted stigma accepts pollen.
The anthers in a flower mature first – an outer ring and then an inner ring – followed by the stigma of the pistil, a sequence that favors cross-pollination (1). A variety of bees, flies and beetles visit the flowers for nectar and pollen, guided, or maybe lured, by the lines on the flowers’ petals. Larvae of several insects also feed on the plant (1).

Collecting seeds from wild geranium can be tricky. As a capsule matures and dries, each of its five parts separates from the central column and curls upward, flinging the seed from the oval chamber at the base. To catch the seeds, it's best to collect the capsules when they just begins to change color. Put them in a closed paper bag to dry and release its seeds. 

The seeds need a period of cold, moist conditions before they will germinate, so either sow them outdoors in fall or treat them artificially (2). Instructions are available from Prairie Moon Nursery, prairiemoon.com.

Left: A nymph of the Fork-tailed Bush Katydid (Scuddaria furcata) visits a Wild Geranium flower. Right: A Thick-headed Fly (Myopa species) sips nectar.


Wild geranium also reproduces vegetatively. Thick rhizomes produce patches of plants that can be divided, ideally in spring or fall. Cut the rhizomes where they make right angles (2). Of course, don’t harvest rhizomes on public land or on private land without permission.

Immature (left) and post-mature (right) capsules of Wild 
Geranium. Seeds have already been released from the 
capsules on the right.

A few plants have leaves that look like wild geranium. Sanicles, also called black snakeroots (Sanicula species), grow in a similar habitat but have alternate leaves on the stem, in contrast to the opposite leaves  of wild geranium. Also unlike wild geranium, Sanicle stems and leaves have no hairs (5). Canada anemone (Anemone canadensis), usually found in wetter habitats than wild geranium, has leaves with sharper teeth (3). Like wild geranium, its stems are hairy, but the hairs are spreading or ascending. In contrast, the hairs on the stems of wild geranium point downward (5)

 


Wild Geranium spreads vegetatively by rhizomes. The largest
one is about as thick as a thumb.

References

(1)    Pollinators of Native Plants, by Heather Holm. Pollination Press, Minnetonka, MN. 2014.

(2)    Wild Geranium, Geranium maculatum. Wisconsin Horticulture, Division of Extension. University of Wisconsin-Madison. Website accessed May 31, 2021. https://hort.extension.wisc.edu/articles/wild-geranium-geranium-maculatum/

(3)    Geranium maculatum (Wild Geranium). Minnesota Wildflowers. Website accessed May 31, 2021. https://www.minnesotawildflowers.info/flower/wild-geranium

(4)    USDA, NRCS. 2021. The PLANTS Database (http://plants.sc.egov.usda.gov, 05/28/2021). National Plant Data Team, Greensboro, NC USA.

(5)    Flora of the Great Plains, by the Great Plains Flora Association. University Press of Kansas, Lawrence. 1986. 






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