Plants....
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Plants....
Tina Wed Dec 31, 2008 11:40 am
Plants…
1. Non-vasclar plants (Bryophytes):
Ans: Non-vascular plants are a general term for those plants without a vascular system. Although non-vascular plants lack these particular tissues, a number of non-vascular plants possess tissues specialized for internal transport of water.Non-vascular plants have no roots, stems, or leaves, since each of these structures is defined by containing vascular tissue. The lobes of the liverwort may look like leaves, but they are not true leaves because they have no xylem or phloem. Likewise, mosses and algae have no such tissues. All plants have a life cycle with an alternation of generations between a diploid sporophyte and a haploid gametophyte, but nonvascular plants include the only plants that have a dominant gametophyte generation. In these plants, the sporophytes grow attached and are dependent on gametophytes for taking in water and other materials. Non-vascular plants grow from spores.
2. Seedless plants (Pteridophytes):
Ans: The pteridophytes are vascular plants that neither flower nor produce seeds, hence they are called vascular cryptogams. Instead, they reproduce and disperse only via spore’s.These living groups of pteridophytes are several groups now extinct and known only from fossils. These groups include the Rhyniophyta, Zosterophyllophyta, Trimerophytophyta, and the progymnosperms.Modern studies of the land plants agree that all the pteridophytes share a single common ancestor. However, they are not a clade because the seed plants are also descended from within this group - probably close relatives of the progymnosperms.
3. Non-flowering plants (Gymnosperms):
Ans: Gymnosperm is a group of spermatophyte seed-bearing plants with ovules on the edge or blade of an open sporophyll, which are usually arranged in cone-like structures. The other major group of seed-bearing plants, the angiosperms, [from the Greek, 'angion' - container] have ovules enclosed in a carpel, a sporophyll with fused margins. A carpel consists of a stigma, style and the ovary. The term gymnosperm comes from the Greek word gumnospermos, meaning "naked seeds" and referring to the unenclosed condition of the seeds, as when they are produced they are found naked on the scales of a cone or similar structure.
4. Flowering plants (Angiosperms):
Ans: The flowering plants or angiosperms are the most widespread group of land plants. The flowering plants and the gymnosperms are the only extant groups of seed plants. The flowering plants are distinguished from other seed plants by a series of apomorphies, or derived characteristics.
By: Tina.....
1. Non-vasclar plants (Bryophytes):
Ans: Non-vascular plants are a general term for those plants without a vascular system. Although non-vascular plants lack these particular tissues, a number of non-vascular plants possess tissues specialized for internal transport of water.Non-vascular plants have no roots, stems, or leaves, since each of these structures is defined by containing vascular tissue. The lobes of the liverwort may look like leaves, but they are not true leaves because they have no xylem or phloem. Likewise, mosses and algae have no such tissues. All plants have a life cycle with an alternation of generations between a diploid sporophyte and a haploid gametophyte, but nonvascular plants include the only plants that have a dominant gametophyte generation. In these plants, the sporophytes grow attached and are dependent on gametophytes for taking in water and other materials. Non-vascular plants grow from spores.
2. Seedless plants (Pteridophytes):
Ans: The pteridophytes are vascular plants that neither flower nor produce seeds, hence they are called vascular cryptogams. Instead, they reproduce and disperse only via spore’s.These living groups of pteridophytes are several groups now extinct and known only from fossils. These groups include the Rhyniophyta, Zosterophyllophyta, Trimerophytophyta, and the progymnosperms.Modern studies of the land plants agree that all the pteridophytes share a single common ancestor. However, they are not a clade because the seed plants are also descended from within this group - probably close relatives of the progymnosperms.
3. Non-flowering plants (Gymnosperms):
Ans: Gymnosperm is a group of spermatophyte seed-bearing plants with ovules on the edge or blade of an open sporophyll, which are usually arranged in cone-like structures. The other major group of seed-bearing plants, the angiosperms, [from the Greek, 'angion' - container] have ovules enclosed in a carpel, a sporophyll with fused margins. A carpel consists of a stigma, style and the ovary. The term gymnosperm comes from the Greek word gumnospermos, meaning "naked seeds" and referring to the unenclosed condition of the seeds, as when they are produced they are found naked on the scales of a cone or similar structure.
4. Flowering plants (Angiosperms):
Ans: The flowering plants or angiosperms are the most widespread group of land plants. The flowering plants and the gymnosperms are the only extant groups of seed plants. The flowering plants are distinguished from other seed plants by a series of apomorphies, or derived characteristics.
By: Tina.....
Tina- Posts : 8
Join date : 2007-12-10
Age : 28
Location : Taiwan
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