Angiosperms vs Gymnosperms
Both angiosperms and gymnosperms are the seed bearing plants. They are the spermatophytes and differ from each other because of their derived characteristics, which is discussed in detail, in this article.
What is Gymnosperm?
Gymnosperms are seed bearing plants. The group includes conifers, cycads, ginkgo, and gnetales. The dominant plant is a sporophyte, and it is differentiated into leaves, stem and roots. Vascular and mechanical tissues are present in these plants. These are dioecious plants, and female plant bears megasporophylls, while male plant bears microsporophylls in a cone. Megasporophylls bear naked ovules, which becomes the seed after fertilization. Both male and female gametophytes are small and depend on the sporophyte. No external water is necessary for their fertilization. The seed germinates to give rise to the sporophyll.
A common example for cycads is cycas. Cycas sporophyte resembles a palm. It possesses a tap root system with secondary roots branching off. Some roots are negatively geotropic, and they are called corolloid roots. In the cortex of these roots, there are cyanobacteria living symbiotically. The stem is pillar like and bears a crown of leaves at the apex. The stem is covered with leaf scars and shows secondary thickening. There are two types of leaves. Vegetative leaves are large and pinnately compound. Young leaves show circinate vernation. Alternatively with vegetative leaves are small brown colored scale leaves. The male plant bears a male cone with microsporophylls. The female plant bears a crown of megasporophylls. The megasporophylls bear naked or exposed ovules on their lateral margin. Gymnosperms are heterosporous.
What is Angiosperm / Anthophyte?
Anthophytes are the most advanced plants in the kingdom plantae. The dominant plant is the sporophyte, which may be dioecious or monoecious. The sporophyte is highly differentiated into stem, leaves and roots with well developed vascular tissues. The xylem contains vessels and the phloem contains sieve tubes and companion cells. They possess a highly differentiated reproductive structure which is the flower. Anthophytes are heterosporous. The ovules develop within the ovary. The ovaries develop by the folding of megasporophylls. Folded megasporophylls are called carpels. When a carpel is formed the ovules are enclosed within the carpel. They have well defined mechanical tissues. There is a well developed cuticle in the terrestrial plants. No external water or internal fluids are necessary for fertilization. Therefore, spermatozoids are non-motile. The pollen tube carries male nuclei or gametes towards the ovum. In anthophytes, there is double fertilization forming a diploid embryo and a triploid endosperm. A true seed is formed within the fruit. Anthophytes are considered to be well adapted for terrestrial life because of some reasons. They have a fully developed vascular system with vessels, sieve tubes and companion cells. They have a highly differentiated plant body into roots, stems and leaves. They have well developed mechanical tissues. They possess a pollen tube to carry male gamete to the ovum. Therefore, the fertilization is not dependent on external water. They have a cuticle and seeds.
What is the difference between Angiosperms and Gymnosperms?
• In gymnosperms, a male cone is present and instead, anthophytes possess a flower.
• Microsporophylls in gymnosperms are modified to stamens in anthophytes.
• Megasporophylls of gymnosperms are modified to carpels in anthophytes.
• An archigonium is present in gymnosperm female gametophyte and no archegonia in anthophyte female gametophyte.
• Multi ciliated sperms are present in gymnosperms and in anthophytes only the nuclei are present.
• An internal fluid is required for fertilization in gymnosperms, and no water is necessary for fertilization in anthophytes.