Garlic mustard - a plant with two faces
Garlic mustard (Alliaria petiolata) was probably brought to North America as a culinary herb (as the name suggests, it can be used as a garlic substitute). It has since gone from the status of an obscure culinary herb to an even more obscure culinary herb. On another front, however, it has gained great notoriety. It is one of the more invasive of the alien plant species that have invaded our region. Garlic mustard can penetrate far into the interior of forests, and competes well, sometimes forming near monocultures in the understory, to the near exclusion of native species.
Garlic mustard is a biennial, which means that in the year the seed germinates, it produces only vegetative growth. In this way, it focuses on using sunlight to join carbon dioxide and water into carbohydrates, which it stores for future use as food. In the second year, the plant uses this stored energy to quickly produce flowers, which then develop into fruits containing the seeds to start the process anew. Seed production has been recorded as high as 107,580 per square meter1.
The appearance of garlic mustard changes from the first year to the second to the point where it would be easy to mistake one species for two. In the first year (see inset photo), the leaves are close to the ground, and are kidney-shaped with rounded teeth - resembling the leaves of a stemless blue violet, or large leaves of ground-ivy. In the second year, the plant produces an upright stem bearing triangular leaves with sharper teeth (the enlarged plant bearing flowers in the photo).
1 Cavers, P. B., M.I. Heagy, and R.F. Kokron. 1979. The biology of Canadian weeds. 35. Alliaria petiolata. Canadian Journal of Plant Science. 59(1): 217-229
The above photo of flowering plants was taken by Stanley W. Arnheim, the insert showing first year plants is by Weidong Chen.
Vote for your favorite WPC Daily in February.
View the winning WPC Daily entry for January (as voted overwhelmingly by our readers)
|
E-mail Today's WPC Daily to a Friend! |