The easiest way to tell narrow-leaved cattail from broad-leaved
is to look for this green gap between the staminate and pistillate
parts of the spike. There is a very short one in broad-leaved
cattail, so that the staminate and pistillate parts are practically close
together. The color of the ripe narrow-leaved spike is much like milk
chocolate, while in broad-leaved it's more like dark chocolate.