The Seedless Vascular Pants: Ferns and Their Relatives

Outline Phylum Psilotophyta (Whisk Ferns) Phylum Lycophyta (Club Mosses) Phylum Equisetophyta (Horsetails) Phylum Polypodiophyta (Ferns) Fossils

Phylum Psilotophyta The Whisk Ferns  Loosely resemble small, green whisk brooms.  Structure and Form - Sporophytes consist almost entirely of dichotomously forking aerial stems.  Have neither leaves nor roots.  Enations spirally arranged along stems. Life Cycle:

Phylum Lycophyta Ground Pines, Spike Mosses, and Quillworts  Collectively called club mosses. - Only two living representatives of two major genera.  Lycopodium  Selaginella  Sporophytes have microphylls.  Have true roots and stems.

Phylum Lycophyta Lycopodium - Ground Pines  Often grow on forest floors.  Resemble little Christmas trees, complete with cones.  Stems are simple or branched. - Develop from branching rhizomes. Reproduction

Phylum Lycophyta Selaginella - Spike Mosses  Especially abundant in tropics.  Branch more freely than ground pines.  Leaves have a ligule on upper surface.  Produce two different kinds of spores and gametophytes (heterospory). Reproduction

Phylum Lycophyta Isoetes - Quillworts  Most found in areas partially submerged in water, and least part of the year.  Microphylls are arranged in a tight spiral on a stubby stem.  Ligules occur towards leaf base.  Corms have vascular cambium. Reproduction

Phylum Equisetophyta The Horsetails and Scouring Rushes  Structure and Form - About 25 species scattered through all continents. - Significant silica deposits accumulate on the inner walls of the stem’s epidermal cells. - Branches, when present, are normally in whorls at regular intervals along the jointed stems.

Phylum Equisetophyta Both branched and unbranched species have tiny microphylls in whorls at the nodes. Leaves fused at their base forming a collar. Stems are distinctly ribbed and have obvious nodes and internodes.  Pith breaks down at maturity leaving a hollow central canal.  Aerial stems develop from horizontal rhizomes. Reproduction

Phylum Equisetophyta Human and Ecological Relevance  Many giant horsetails used for food.  Scouring rush stems used for scouring and sharpening.

Phylum Polypodiophyta The Ferns  Structure and Forms - Approximately 11,000 known species of ferns vary in size from tiny floating forms less than 1 cm to giant tropical tree ferns up to 25 m tall.  Fern leaves are megaphylls that are commonly referred to as fronds.  Typically divided into smaller segments.

Spore Release From a Fern Sporangium

Phylum Polypodiophyta Human and Ecological Relevance  Extremely popular house plants. - Serve as air filters.  Cooked rhizomes serve as food.  Folk Medicine  Fronds used in thatching houses.

Fossils A fossil is generally defined as any recognizable prehistoric organic object preserved from past geological ages.  Conditions of formation almost always include quick burial in an accumulation of sediments. - Hard parts more likely preserved than soft parts.

Fossils Molds, Casts, Compressions, and Imprints  After being buried in sediment, the organic material may be slowly washed away by water percolating through the rock pores. - If air space remains - Mold - If silica fills space - Cast  Compression takes place when objects are buried by layers of sediment and greatly compressed so that only a thin outline is left.

Fossils Petrifications  Petrifications are uncompressed rock-like material in which the original cell structure has been preserved.

Review Phylum Psilotophyta (Whisk Ferns) Phylum Lycophyta (Club Mosses) Phylum Equisetophyta (Horsetails) Phylum Polypodiophyta (Ferns) Fossils

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