Thursday, May 12, 2016

Cat got your tail? - Identifying Cattails

A marsh with mixed cattail species

The cattail is one of the most recognized species of plants in the world.  It grows throughout North America and Europe.  Here is Mid-Michigan we have two distinct species of cattail and one hybrid.  Identifying the different species is easy if you know what to look for.

So how do you tell the difference between the species?

The two species of cattail in Michigan are the Common Cattail (Typha latifolia) and the Narrow-Leafed Cattail (Typha angustifolia).  Both species inhabit shallow water in marshes, swamps, lakes, ponds, and streams.  Both species grow from from 1 to 3 meters tall.  Both species have narrow-sword shaped leaves.  The leaves of the common cattail are typically 1-2 centimeters wide; the narrow-leafed cattail as its name implies has narrower leaves (up to 1 cm wide).  This difference in leaf width is not enough by itself to identify the two species because there is some overlap in size.  The two species also interbreed to form a hybrid Typha X glauca.  The hybrid is often taller than both parents.

The best way to identify the two species is to look at the "cat tail" that gives this plant its name.  The tail is actually the flower (and seed head) of the plant.  The flower comes in two parts a male part and a female part.  Both parts of the flower are shades of green. The female half of the flower is lower on the stem than the male half.  After pollination, the female part turns from green to brown and produces fluffy seeds that are spread by the wind.  The male half of the flower is absent after pollination.

On the common cattail, the two halves of the flower touch.

Common Cattail - note that the male and female halves of the flower touch.

On the narrow-leaved cattail, there is a distinct gap between the male and female halves of the flower. 

Narrow-leaved Cattail - note gap between male and female halves of the flower

 The gap between the male and female halves of the flower can vary from 1 to 4 centimeters.  The plant above has a wide gap, the ones below are narrower.

Another example of  Narrow-leafed Cattail.  These plants show a narrower gap between the flower halves.
Noticing this gap is all there is to separating the two species.  This can even be identified in plants that lack the male half of the flower because they have gone to seed.  Look for a change in the diameter of the stem above the seed head to identify where the male part of the flower began.

A change in the diameter of the stem above the flower identifies these as Narrow-leafed Cattails.

The hybrid also has a gap between the two halves of the flower, but there is no reliable way to identify it in the field.

The common cattail is widely recognized as being native to Michigan, but there is some debate about the origin of the narrow-leafed species.  Some books list the plant as native, others show the plant as being introduced from the Atlantic Coast or possibly from Europe.  What is generally agreed upon is that the narrow-leafed cattail is a more aggressive species and will crowd out the common cattail from wetlands over time.  In fall and winter, both species readily spread their light, wind-borne seeds to form colonies in new wetlands.

Fluffy seedheads ready to disperse in the wind

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