Pteridophytes (chapter 17)
Pteridophyte characteristics |
They are vascular (they have roots, stems, and leaves) |
The cells are cylindrical or elongated, and network throughout the plant |
Xylem moves water and ions (positive and negative) around the plant |
Phloem moves organic molecules, like sugars, around the plants |
The sporophyte is the dominant phase in the life cycle |
Pteridophytes (chapter 17)
Club mosses - the Lycophytes |
Selaginella is the only genus of the family Selaginellaceae |
Most are found in tropical areas, and a few (seven genera) are found in the US and Canada |
The club mosses are homosporous |
Selaginella has an herbaceous sporophyte that bears microphylls. Its sporophylls are arranged in strobili |
Selaginella has a ligule (small, scalelike outgrowth) with unisexual gametophytes |
The club mosses have sporangia, which are modified leaves (or leaf-like organs) that bear the spore-producing sporangia |
Each sporophyte of Selaginella has a single sporangium |
In the US and Canada, nonphotosynthetic sporophylls are grouped into strobili (cones) at the ends of the aerial branches |
Megasporophylls produce megasporangia |
Spores of club mosses bring bisexual gametophytes about during germination |
Microsporophylls produce microsporangia |
Megasporangia and microsporangia occur in the same strobilus |
The sperm of Selaginella require water to swim to the archegonia and fertilize the eggs. Fertilization occurs after the gametophytes have been shed from the strobilus |
Isoetes, the quillworts, is the only genus of the family Isoetaceae |
Isoetes is heterosporus |
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Pteridophytes (chapter 17)
Ferns - the Monilophytes |
The phylum Monilophyta is made up of the ferns and horsetails |
There are four major lineages of the Monilophytes: the Psilotopsida, the Marattiopsida, the Polypodiopsida, and the Equisetopsida |
Ferns are either eusporangiate or leptosporangiate, in terms of the structure and method of development of their sporangia |
In a eusporangium, the parent cells (or initials) are located at the surface of the tissue from which the sporangium is produced |
Leptosporangia come from a single superficial parent cell, which divides transversely or obliquely |
Sporangia are stalked, and each has a special layer of unevenly thick-walled cells called an annulus |
The leaves, or fronds, of the Polypodiopsida are called fronds. The fronds are megaphylls, and they're the most conspicuous part of the sporophyte |
The ferns are the only seedless vascular plants to have well-developed megaphylls |
The fronds are compound; the lamina is divided into pinnae (leaflets), which are attached to the rachis (extension of the leaf stalk) |
In almost all ferns, the young leaved are circinate (coiled), and they're referred to as "fiddleheads" |
Circinate venation refers to the type of leaf development in which leaves of young ferns are curled |
In many genera of ferns, young sori are covered by specialized outgrowths of the leave called the indusia (singular: indusium) |
The sporangia occur in clusters called sori (singular: sorus) |
Gametophytes typically develop rapidly into a flat, heart-shaped structure called the prothallus |
The water ferns are heterosporous, leptosporangiate ferns |
The rhizomes of the water ferns grow in the mud, in damp soil, or often with the leaves floating on the surface of the water |
The leaves of Marsilea resemble the leaves of a four-leaf clover |
Azolla and Salvinia are small ferns that float on top of the water |
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Gymnosperms: chapter 18
Coniferophyta (the conifers) |
Cycadophyta (the cycads) |
Ginkgophyta (ginkgo, or maidenhair tree |
Gnetophyta (the gnetophytes) |
Gymnosperms
Characteristics of gymnosperms |
Seeded, vascular plants |
There are extinct and living gymnosperms |
The extinct gymnosperms are the seed ferns and the cordaites |
There are four phyla of living gymnosperms. They are: Coniferophyta (the conifers), Cycadophyta (the cycads), Gingkophyta (the gingko, or maidenhair, tree), and Gnetophyta (the gnetophytes) |
Their seeds and ovules are exposed on sporophylls (modified leaves) |
Microgametophytes (male gametophytes) develop as pollen grain. Water isn't required as a medium for transporting the sperm to the egg |
Pollination is when the pollen grain (partly developed microgametophyte) is transferred bodily to the vicinity of a megagametophyte (female gametophyte) within an ovule |
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