Pteridium aquilinum (Linnaeus) Kuhn
var. latiusculum (Desv.) Underw. ex A.Heller
bracken fern
Family: Dennstaedtiaceae

ultimate segments
false indusium

Pteridium aquilinum is a common and distinctive fern in Wisconsin. The blades are 3-pinnate (at least at the base), broadly triangular and are often held more or less horizontally. Sori are borne along the margins of the segments and are covered by the false indusium (and a true indusium beneath the false). The blades tend to be large and although they are spread out along a rhizome they often form stands dense enough to thoroughly shade the ground beneath. Four varieties of this species are recognized, but only variety latiusculum is present in Wisconsin.

Pteridium aquilinum var latiusculum ranges from Newfoundland to Florida, west to Texas and southeastern Manitoba. In Wisconsin it is common throughout the state in forest clearings, barrens, pastures, roadsides and other uncanopied sites and persists long after forest has reclaimed cleared areas. Extensive, robust stands often develop after clear-cutting of trembling aspen. In number of fronds produced it is probably the most numerous fern in Wisconsin.

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