Polypodium virginianum, commonly known as Rock Polypody, Rock Cap Fern, or Common Polypody, is a small evergreen

Evergreen

In botany, an evergreen plant is a plant that has leaves in all seasons. This contrasts with deciduous plants, which completely lose their foliage during the winter or dry season.There are many different kinds of evergreen plants, both trees and shrubs...

 species of fern

Fern

A fern is any one of a group of about 12,000 species of plants belonging to the botanical group known as Pteridophyta. Unlike mosses, they have xylem and phloem . They have stems, leaves, and roots like other vascular plants...

 native to the Eastern United States

Eastern United States

The Eastern United States, the American East, or simply the East is traditionally defined as the states east of the Mississippi River. The first two tiers of states west of the Mississippi have traditionally been considered part of the West, but can be included in the East today; usually in...

 and Canada

Canada

Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

. It generally grows on rocks and occasionally on tree roots in nature.

Description

Polypodium virginianum is a small rhizomatous

Rhizome

In botany and dendrology, a rhizome is a characteristically horizontal stem of a plant that is usually found underground, often sending out roots and shoots from its nodes...

 fern

Fern

A fern is any one of a group of about 12,000 species of plants belonging to the botanical group known as Pteridophyta. Unlike mosses, they have xylem and phloem . They have stems, leaves, and roots like other vascular plants...

  with narrow leaves 8-40 cm long and 3-6 cm wide borne on smooth, scaleless petioles

Petiole (botany)

In botany, the petiole is the stalk attaching the leaf blade to the stem. The petiole usually has the same internal structure as the stem. Outgrowths appearing on each side of the petiole are called stipules. Leaves lacking a petiole are called sessile, or clasping when they partly surround the...

 (3-15 cm). Leaves are evergreen, oblong and pinnatifid

Pinnate

Pinnate is a term used to describe feather-like or multi-divided features arising from both sides of a common axis in plant or animal structures, and comes from the Latin word pinna meaning "feather", "wing", or "fin". A similar term is pectinate, which refers to a comb-like arrangement of parts...

 with acuminate tips.

Large, circular sori are prominently featured on the underside of fertile fronds

Frond

The term frond refers to a large, divided leaf. In both common usage and botanical nomenclature, the leaves of ferns are referred to as fronds and some botanists restrict the term to this group...

 in late summer and autumn. Sporangia

Sporangium

A sporangium is an enclosure in which spores are formed. It can be composed of a single cell or can be multicellular. All plants, fungi, and many other lineages form sporangia at some point in their life cycle...

 are intermixed with long brown glandular hairs.

Taxonomy

Polypodium virginianum has several synonyms including: P. vinlandicum A. Love & D. Love, P. vulgare L. var. americanum Hooker, P. vulgare L. var. virginianum (L.) D. C. Eaton. It is generally treated as distinct, though some have recommended it is equally well treated as a North American variety of the circumboreal P. vulgare.

This species is an allotetraploid of hybrid origin, the parents being Polypodium appalachianum

Polypodium appalachianum

Polypodium appalachianum is a recently-recognized fern species, native to eastern North America. Sometimes called the Appalachian rockcap fern, it is very similar in appearance to Polypodium virginianum. For years, P...

and P. sibiricum.

Habitat and distribution

Polypodium virginianum typically grows on boulders, cliffs, and rocky slopes and does not need well-developed soil. It is common throughout Eastern North America; its native distribution ranges from Newfoundland

Newfoundland and Labrador

Newfoundland and Labrador is the easternmost province of Canada. Situated in the country's Atlantic region, it incorporates the island of Newfoundland and mainland Labrador with a combined area of . As of April 2011, the province's estimated population is 508,400...

 to Yukon

Yukon

Yukon is the westernmost and smallest of Canada's three federal territories. It was named after the Yukon River. The word Yukon means "Great River" in Gwich’in....

 south to Georgia

Georgia (U.S. state)

Georgia is a state located in the southeastern United States. It was established in 1732, the last of the original Thirteen Colonies. The state is named after King George II of Great Britain. Georgia was the fourth state to ratify the United States Constitution, on January 2, 1788...

, Alabama

Alabama

Alabama is a state located in the southeastern region of the United States. It is bordered by Tennessee to the north, Georgia to the east, Florida and the Gulf of Mexico to the south, and Mississippi to the west. Alabama ranks 30th in total land area and ranks second in the size of its inland...

, and Arkansas

Arkansas

Arkansas is a state located in the southern region of the United States. Its name is an Algonquian name of the Quapaw Indians. Arkansas shares borders with six states , and its eastern border is largely defined by the Mississippi River...

.