Nature Notes

Vol. XII July, 1934 No. 7

Sword Fern
(Polystichum munitum (Kaulf.) Presl.)

Referred to occasionally as the "Christmas Fern" - because in some parts of the country the fronds of closely related and somewhat similar species are used for Yule tide decorations - this plant is one of the most abundant, beautiful and distinctive in the park. It is native to the humid transition and lower Canadian zones; from the park boundaries to 3500'. The wide spreading clumps of dark glossy-green leathery fronds (18"-30" long) add their bit to the semi-tropical appearance of parts of the dense, shaded woodland in which they grow.

sketch of sword fern

sword fern frond

The Sword Fern is evergreen. The pinnae are linear-lanceolate in outline and with edges bordered with numerous ragged "teeth". The fruit dots (sori) are found upon the underside of the pinnae and are arranged in a double row - one row on each side of the prominent mid vein. They are round in general outline and enlarge and spread as the sporangia, which compose them, mature. The root stalks are stout and creeping with erect crowns rising above the surface of the soil to bear the whorls of fronds. The Sword Fern is a common one from Alaska to Calif. and east to Idaho - in situations suited to its growth and development. Closely related species are also common in many parts of the country. (See Nature Notes, April 1934, page 35 for the short article entitled "How a Fern Grows"). C.F.B.

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