+ Phylum Lycophyta

 Three groups of lycophytes exist today:

 1. Lycopods, which are often called club mosses or ground pines can be found looking a lot like little pine trees as they grow along the forest floor in temperate regions. + Phylum Lycophyta

 2. Spike mosses are flatter and more moss-like in their appearance than the lycopods. Some species of the spike moss like Selaginella are know for their ability to survive in harsh, dry conditions. Other species grow within the tropical rainforest canopy. + Phylum Lycophyta

 3. Quillworts are spiky little plants that almost look like tufts of grass and are typically found growing in marshy areas. + Structure of lycophytes

 Lycophytes have true leaves, roots, and stems that contain vascular tissue.

 The leaves of lycophytes are microphylls. + Sporophyte growth form

 Club Mosses…..

 Branches: Shoots may be branched or unbranched. Shoots that do branch spit evenly, making symmetrical forks in a type of branching called isotomous branching.

 Leaves: Small leaves wrap around the stems, either in a spiral or in individual rings of leaves called whorls.

 Roots: Adventitious + Sporophyte growth form

 Spike Mosses…..

 Branches: Shoots usually look flat, and their branching is typically anisotomous—when the shoot splits, one branch at the fork grows longer than the other.

 Leaves: Small leaves are arranged in spirals around the shoot. At the base of each leaf is a small flap of extra tissue called a ligule—which means tongue.

 Roots: Adventitious roots, sometimes called rhizophores, look like little brown strings dangling down from the stem and then growing into the soil. + Sporophyte growth form

 Quillworts…..

 Branches: The short, thick stems of quillworts form perennial underground corms.

 Leaves: Longer leaves are arranged in a tight spiral around the short stem, growing up like tufts of quills. Bases of leaves have ligules.

 Roots: Adventitious and dichotomously branched. + Life cycles of lycophytes

 Within the lycophytes, club mosses are homosporous, while spike mosses and quillworts are both heterosporous.

 When lycophyte sporophytes are ready to make spores, they produce little bean-shaped sporangia that are tucked into the pockets, or axils, where the leaves meet the stem.

 Leaves that have sporangia on them are called sporophylls.  If megasporangia, then megasporophylls  If microsporangis, then microsporophylls + Life cycles of lycophytes

 In some lycophytes, the sporophylls look very similar to other leaves and are mixed in among them in zones along the stem.

 In others, the sporophylls are small and brown and clustered together in cone-like structures called strobili. + Life cycles of lycophytes

 Life cycle of the club moss, Lycopodium, as an example of homosporous lycophytes…..

 1. Mature diploid sporophytes produce sporangia on sporophylls.  Within the sporangis, spore mother cells divide by meiosis to produce haploid spores.

 2. The spores are released into the air, and when they land in a suitable environment, they begin to grow by mitosis to produce the haploid gametophyte.

Lycopodium

Life cycle of the club moss, moss, club the of cycle Life + + Life cycles of lycophytes  3. Club moss gametophytes are monoecious, so each gametophyte produces both archegonia and antheridia on its surface.  Cells within archegonia divide by mitosis to produce a single egg in each archegonium. Cells within antheridia divide by mitosis to produce sperm.

 4. When moisture is available, the sperm swim to the eggs and fertilize them, forming the diploid zygote.  The zygote divides by mitosis, producing first the embryo and then growing into the sporophyte.

 Some club mosses also reproduce asexually by producing little structures called bulbils in the axils of their leaves. The bulbils can fall off and grow into new sprorphytes.