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Ecological Manual of New York City Plants

Ferns and related (seedless, vascular) plants (Pteridophyta):

Ferns (Filicopsida: all fern families), horsetails (Equisetaceae) and club mosses (Lycopodiaceae) are vascular *, non-flowering plants that do not produce seed (Maddison and Schulz 2004). All of these seedless, vascular plants have a life cycle separated into two distinct stages. The large plant, called the sporophyte (spore producing plant), produces spores by meiosis, the cell division process that creates sex cells. Cells produced by meiosis have only one copy of each gene (i.e. one set of chromosomes rather than two). These “haploid” spores germinate and produce the second life cycle stage called the gametophyte (gamete-producing). Gametophytes are either very small, green, moss-like plants, in the case of most ferns and horsetails, or underground tuber-like plants closely associated with, and dependent upon, specific types of mycorrhizal fungi, in the case of many club mosses. The gametophyte produces haploid sex cells (gametes: sperm and eggs) by ordinary cell division (mitosis). Sperm requires water to swim to the eggs (usually rain). The resulting fertilization produces a diploid sporophyte plant with the standard, two sets of chromosomes (i.e. two copies of each gene). As is evident from the above, these plants produce neither flowers nor seeds. Spores are generally produced in specialized parts of the plant. Ferns may have spore cases (sporangia) on the undersides of some leaves or leaves that specialize entirely in spore case production. Club mosses and horsetails often produce spore cases in cone-like structures, usually at the tips of stems.

*A vascular plant is one with “veins” made up of tube-like xylem and phloem cells that conduct water and nutrients to and from roots and throughout the plant.

Ferns (Pteridophyta)

New York City has lost nearly 40% of ferns found here prior to 1980 (DeCandido 2000).