Chapter 12 



FERNS AND THEIR ALLIES 



Higher Plants With Chlorophyll; With True Leaves, Stems, 

 AND Roots; With Vascular Tissues (Phloem and Xylem) ; With- 

 out Seeds; Forming Multicellular Embryos (Subkingdom Em- 

 bryophyta) 



GENERAL CHARACTERISTICS OF FERNS AND THEIR ALLIES 

 (CLUB "MOSSES" AND HORSETAILS) 



1. Ferns and their allies belong to the subkingdom Embryo phyta be- 

 cause they form multicellular embryos and to the phylum Tracheophyta 

 because they possess true vascular tissues of varying degrees of complexity. 



2. The phylum Tracheophyta includes such subphyla as ( 1 ) Lycopsida 

 (club ''mosses") having simple vascular tissues, small, green leaves, usually 

 spirally arranged, and branched stems and roots, (2) Sphenopsida 

 (horsetails), having a simple vascular system, small leaves in whorls 

 (sometimes scalelike), jointed, and hollow stems which are usually rough- 

 ened by ribs and silica, and (3) Pteropsida (ferns), having a rather com- 

 plex vascular system and usually large, conspicuous leaves. 



3. Tracheophytes possess true leaves, stems, and roots, skeletal mate- 

 rials for upright growth, stomata for the exchange of gases, and a pro- 

 tective layer of cutin. 



4. Club "mosses," horsetails, and ferns have somewhat similar methods 

 of reproduction and life cycles. 



5. The gametangia (sex organs) are multicellular, as in the Bryophytes, 

 but in contrast to the unicellular sex structures of the Thallophytes. 



6. Tracheophytes possess an alternation of generations in which a 

 gamete-producing gametophyte generation alternates with a spore-form- 

 ing sporophyte generation. 



7. The gametophyte bears characteristic multicellular sex organs 

 known as the male antheridia and the female archegonia. 



8. The sporophyte is relatively large and independent (with true 

 leaves, stems, and roots), while the gametophyte is usually rather small 

 and inconspicuous (contrast with bryophytes) . 



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