SporePlants213-page16 - rhizome or basal stem...

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Spore-Dispersing Vascular Plants - 16 Structural Characteristics of the Ferns Ferns are usually homosporous. The aquatic ferns are heterosporous. The vascular stem is usually an underground rhizome, or a basal stem. In tree ferns the stem is columnar, with leaves forming much of the diameter of the stem. The fern leaf is called a frond. Fronds are megaphylls, with well-developed vascular tissue. The "petiole" is called a rachis. Many fern fronds are highly dissected. Compound leaves are common. Separate sporangia-producing (fertile) and vegetative (sterile) fronds are produced in many fern species. In colder habitats, the fronds die each year, and new growth is produced from the
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Unformatted text preview: rhizome or basal stem. Fronds "emerge" by circinnate vernation, a nearly unique uncoiling process. The uncoiled young fern fronds are called fiddleheads. Spores are produced in sporangia located in a sorus, which usually has a protective indusium. The indusium is a special layer of leaf tissue. The sori and their protective indusia (plural forms) vary in shape and are located on the underside of fertile fronds. Indusium location and shape is used in fern identification. Fern sori with Indusia Sori lacking an indusium...
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This note was uploaded on 01/08/2012 for the course BIO 213 taught by Professor Makina during the Fall '09 term at SUNY Stony Brook.

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