I would like to start a topic on the interesting Bryophyta and Tracheophyta phylums. Any facts about the two groups would be acceptable. Thanks for posting!
Thanks for pointing that out Knights. Here is an article on the Bryophyta phylum. I would like to know more about the two phylums as well, as my knowledge on this topic is somber. Here are some articles on the Bryophyta and Tracheophyta phylums...
Phylum Bryophyta
Bryophytes include the mosses, liverworts, and hornworts. Bryophytes are the simplest of plants (excluding the algae, which are not considered plants by most botanists). Bryophytes are small, seldom exceeding 6-8 in (15-20 cm) in height, and usually much smaller. They are attached to the substrate (ground, rock, or bark) by rhizoids, which are one or a few-celled, root-like threads that serve only for anchoring and are not capable of absorbing water and nutrients from the substrate. Brypohytes lack vascular tissue (the specialized cells grouped together to pipe water and nutrients to various parts of the body), or in the rare cases when this tissue is present, it is not well differentiated. The leaves of bryophytes are technically not true leaves, because in most species they lack vascular tissue. However, they are functionally equivalent to leaves, containing chlorophylls a and b for photosynthesis. Leaves are usually one-cell thick, except for the midrib, which may be up to 15 cells thick. Bryophytes satisfy their nutritional requirements by absorbing minerals from dust, rainfall, and water running over their surface.
The life cycle of bryophytes is characterized by an alternation of generations, one of which is a multicellular, diploid individual called a sporophyte, having two of each type of chromosome per cell. This stage alternates with multicellular, haploid individual called the gametophyte, with only one of each type of chromosome per cell, as is also the case with animal sperm. Bryophytes are unique among plants in that the dominant, conspicuous generation is the haploid gametophyte. In all other plants, the dominant stage is the diploid sporophyte.
Most reproduction of bryophytes is asexual, occurring by fragmentation of body parts, and by the production of specialized vegetative units called gemmae. Gemmae may be produced as microscopic plates (in the genus Tetraphis), as bulbils in the axils of leaves (in Pohlia), or as microscopic filaments (in Ulota). When sexual reproduction occurs, it always involves a flagellated sperm (produced in a specialized organ called an antheridium) that must swim through water to reach an egg located in a specialized, flask-shaped organ (the archegonium). The antheridia and archegonia are surrounded by a layer of sterile cells, which protects the sex organs from mechanical damage and desiccation.
Phylum Tracheophyta
The phylum Tracheophyta is an extremely large and diverse group and contains almost all of the terrestrial plants, or what people consider plants. The group probably arouse in the early Silurian with the evolution of a remarkable new cell type, the tracheid. These tracheids strung together provided plants with a plumbing system (vascular system) that allowed water and nutrients to be moved through the plant. This innovation is important because it provided a route for the long-distance movement of water and nutrients from a source to where they were needed and it also served as a structural support system. These two functions allowed plants to adopt a truely terrestrial existence.
Edited by Darius of Parsa - 16-Nov-2007 at 18:04