Tuesday, August 13, 2013

Names the Make Kids Laugh - Duck Potato

Take the word "Duck" and add "Potato" after it.  Duck Potato.  How could combining those two words not make a kid laugh?  What exactly is a Duck Potato?

The Duck Potato is found throughout most of North America, but is most common in the eastern United States.  Overall it is native every state of the Lower Forty-eight except Nevada.  It is found across Canada in all ten provinces.  It's range extends south through the Caribbean and into South America.  It has been introduced into (and is considered invasive in) Hawaii, Australia, and Europe.

With a range this large, why do more people not know about this plant?

Perhaps it is because Duck Potato is not the name by which it is best known.  It is better known by a name whose origin should be completely obvious.  You may not know the Duck Potato, but you are likely to be aware of the Common Arrowhead.  There are ten species of Arrowhead distributed across North America, but Common Arrowhead (Sagittaria latifolia) is the most widespread.  The leaves of the Common Arrowhead are distinctly shaped like arrowheads.

Rising to a height of 6 to 36 inches, Common Arrowhead is typically an emergent plant of shallow wetlands.  It can growing in shallow mud along streams, shorelines, ditches, lakes, and marshes.  The leaves of the Common Arrowhead grow on long stems arranged in a basal cluster.  There is a lot of variation in the shape and size of the leaves.  Leaves of emergent plants may be broadly or narrowly arrow-shaped, those of submersed plants may be be grasslike.

Common Arrowhead with broad leaves
Common Arrowhead with narrow leaves

A narrow-leafed form of the S. latifolia that is commonly found in Michigan is occasionally known as Narrow-leafed Arrowhead (Sagittaria latifolia forma gracilis).

Narrow-leafed Arrowhead (S. latifola f. gracilis)
The flowers of the Common Arrowhead are arranged on a separate stalk (raceme) in the center of the basal cluster of leaves.  The flowers grow in whorls along the stem, with three flowers in each whorl.  Each individual flower may be up to 1 inch (or slightly more) across. 

Individual plants will have both male and female flowers.  Each flower is composed of  three green sepals and three white petals with a pearly luster.  The sepals are shorter than the petals.  The petals surround either six (or more) yellow stamens or green pistils.  Normally the male (staminate) flowers will occur higher on the stalk than the female (pistillate) flowers.  The flowers bloom sequentially from the bottom of the raceme to the top ensuring cross-pollination.Occasionally pistils and stamens will occur on the same flower. 

So why is the plant known as the Duck potato?

The plant reproduces from seed, but it in the fall in northern habitats it also sometimes produces small tubers (corms) on its roots that allow it to reproduce vegetatively.  These corms, like those of a lily, are storage devices for starch that give the plant an important jump-start on growth in the following year.

These corms are readily eaten by wildlife.  Oddly enough, while they are readily consumed by muskrats, geese, and swans, ducks rarely consume the corms.  In fact, many Native American tribes refer to the plant as the "Swan Potato" rather than the Duck Potato. The Anishinaabe name for Common Arrowhead is waabiziipin (Swan tuber/potato) combining the words waabizii (swan) and opin (potato). 

In addition to feeding wildlife, the corms from the plant served as an important food for many Native American tribes.  The corms were gathered in the fall and early winter after the vegetation had died back for the year.  Women of many tribes would wade into the shallow waters where the plants could be found and seek out the corms with their feet.  Once their feet had freed the corms from the mud, the corms (potatoes) would float to the surface where they could be gathered.  The corms were then stored like any other root vegetable and used as important source of starch throughout the winter months.  The Duck Potato was such an important source of food for many tribes that it was mentioned repeatedly in the journals of the Lewis and Clark expedition.

I wanted to take a picture of one of the "potatoes" but after digging around several Common Arrowhead plants I was unable to find any.  My guess is that it is just too early in the year to find them.  I will go back sometime in the fall and if I find any I will post a followup to this blog.

Basic Information

Common Arrowhead (Duck Potato)

Sagittaria latifolia

Height:  6-36” tall

Habitat:  aquatic, ditches, streams, shorelines, marshes

Flower Color:  white with yellow center

Bloom Time:  July – September

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