Polystichum vestitum, commonly known as the Prickly Shield Fern, is a hardy, 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...

 or semi-evergreen ground 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...

.

Description

Polystichum vestitum is a terrestrial fern with an erect and scaly rhizome

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...

, sometimes forming a short trunk and growing up to 700 mm in height. The frond

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...

s are 220–600 mm long. There are 3–7 (usually 5) round sori

Sorus

A sorus is a cluster of sporangia .In fungi and lichens, the sorus is surrounded by an external layer. In some red algae it may take the form of a depression into the thallus....

 on each pinnule, halfway between the margin and midrib, with a light brown indusium.

Distribution and habitat

The fern is native to the three principal islands of New Zealand

New Zealand

New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

 and the Chatham Islands

Chatham Islands

The Chatham Islands are an archipelago and New Zealand territory in the Pacific Ocean consisting of about ten islands within a radius, the largest of which are Chatham Island and Pitt Island. Their name in the indigenous language, Moriori, means Misty Sun...

, as well as to New Zealand’s subantarctic

Subantarctic

The Subantarctic is a region in the southern hemisphere, located immediately north of the Antarctic region. This translates roughly to a latitude of between 46° – 60° south of the Equator. The subantarctic region includes many islands in the southern parts of the Indian Ocean, Atlantic Ocean and...

 Snares, Antipodes

Antipodes Islands

The Antipodes Islands are inhospitable volcanic islands to the south of—and territorially part of—New Zealand...

, Auckland

Auckland Islands

The Auckland Islands are an archipelago of the New Zealand Sub-Antarctic Islands and include Auckland Island, Adams Island, Enderby Island, Disappointment Island, Ewing Island, Rose Island, Dundas Island and Green Island, with a combined area of...

 and Campbell Islands

Campbell Island, New Zealand

Campbell Island is a remote, subantarctic island of New Zealand and the main island of the Campbell Island group. It covers of the group's , and is surrounded by numerous stacks, rocks and islets like Dent Island, Folly Island , Isle de Jeanette Marie, and Jacquemart Island, the latter being the...

, and to Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

’s Macquarie Island

Macquarie Island

Macquarie Island lies in the southwest corner of the Pacific Ocean, about half-way between New Zealand and Antarctica, at 54°30S, 158°57E. Politically, it has formed part of the Australian state of Tasmania since 1900 and became a Tasmanian State Reserve in 1978. In 1997 it became a world heritage...

.

Macquarie Island

On Macquarie it dominates the fernbrake communities which typically occur on the eastern, leeward side of the island on valley slopes and sheltered valley floors. Although it can form dense stands in which few other plants will grow, more commonly it is found in conjunction with Stilbocarpa polaris

Stilbocarpa polaris

Stilbocarpa polaris, commonly known as the Macquarie Island Cabbage, is a species of flowering plant usually placed in the family Araliaceae. It is a megaherb, growing up to about a metre in height, native to the subantarctic islands of New Zealand and to Australia’s Macquarie Island. It was used...

, Poa foliosa

Poa foliosa

Poa foliosa is a species of tussock grass commonly known as Muttonbird Poa. It is native to the subantarctic islands of New Zealand and Australia.-Description:...

and Pleurophyllum hookeri

Pleurophyllum hookeri

Pleurophyllum hookeri, also known as the Silver-leaf Daisy or Sage-green Rosette Herb, is a herbaceous plant in the daisy family, a megaherb native to the subantarctic Auckland and Campbell Islands of New Zealand and Australia’s Macquarie Island...

. The fern is seriously affected by rabbit

Rabbit

Rabbits are small mammals in the family Leporidae of the order Lagomorpha, found in several parts of the world...

 grazing

Grazing

Grazing generally describes a type of feeding, in which a herbivore feeds on plants , and also on other multicellular autotrophs...

.