PTERIDOPHYTE LIFE CYCLE Like the bryophyte cycle, the pteridophyte cycle also requires water for fertilization in order for the sperm to swim to the egg. However, they are dominant in the sporophyte stage. As you may have seen, the mature sporophyte of a fern develops small haploid spores on the underside of their fronds. These are called sporangia, or the singular sporangium. They are also grouped into clusters known as sori, or the plural sorus. (Shown below to the left).These hold spores, which contain sperm.
When these spores are released from the sporangium, they germinate into haploid gametophytes, then grow a set of rhizoids. These rhizoids then go flat and form a heart shaped prothallus, known as the mature gametophyte. This grows independent of the sporophyte.
Unlike other plants, the gametophyte has both the antheridia and the archegonia on the same plant. After fertilization, a diploid zygote is produced and a new sporophyte plant forms. As this grows, the gametophyte dissolves and the new sporophyte lives on for often many years. This full cycle is shown below to the right.
EXAMPLES OF PTERIDOPHYTES Some examples of pteridophytes are shown below, such as club mosses (left), horsetails (middle), and ferns (right).
COMPARE AND CONTRAST: BRYOPHYTES AND PTERIDOPHYTES Unlike pteridophytes, bryophytes are non- vascular, so they move water through osmosis and nutrients through diffusion. Pteridophytes, on the other hand, are vascular, so they transport water in their xylem (roots to shoots), and photosynthesis products in their phloem (shoots to roots), as well as their leaves and hyphae- root like structures that anchor the fern to the ground. As a result of having vascular tissue, pteridophytes can grow larger. Bryophytes also have a lifecycle dominant by the gametophyte stage, while pteridophytes are sporophyte dominant.
There are also a lot of similarities between these two groups, however. They both need water for fertilization, and use spores as a part of reproduction. They also both have sperm that have a flagella, and have to swim to the egg.