Non vascular plants and most seedless vascular plants are homosporous, which means that they only produce one type of spore. Now, some seedless vascular plants and all the seed plants are heterosporous, meaning that they produce 2 distinct types of spores. And those 2 distinct types are microspores, which are made from microsporangia, and these develop into male gametophytes. So these ultimately lead to the production of sperm. And then you have megasporangia, which produce megaspores, and those megaspores will develop into female gametophytes or eggs. Now, in terms of reproduction, non vascular plants and seedless vascular plants have a big disadvantage compared to later plants. And that is that their sperm requires water in order to get to the egg. Not only does it require water, but it basically requires a continuous path of water to get to the egg. So essentially, this means that those organisms can only reproduce when it's wet out and this kind of restricts them to environments where there's enough moisture. The adaptation of pollen, which is the male gametophyte surrounded by a spore and pollen encoding, basically it's just like a tough coating. Allows for the male gametophytes, and ultimately the sperm to exist without water for a much longer period of time. They can be exposed to the air for a long time and furthermore, they can actually take advantage of the air as a medium through which to travel to the egg. So pollen was a huge, important adaptation and it essentially allows the sperm to travel through the air to the egg and not require water to actually fertilize the egg, and we'll talk about the specifics of that later when we talk about seed plants. Now the seed itself, as I said, was a big evolutionary adaptation. And the seed is basically just the embryonic plant, right? The embryo of the plant and a food supply. And this is all surrounded by a tough coating that allows the seed to resist environmental damage and degradation from being digested by an organism, for example. And seeds form from fertilization by pollen. You can see pollen here. All these little yellow dots are bits of pollen. Here we actually have an electron microscope image of pollen. You can see that there's a lot of diversity in form. Pollen can take a lot of different shapes. And here we actually are looking at the inside of seeds. This is a seed cut in half, and let me jump out of the image here. This is our embryonic plant. It's a dicot. You'll learn why later. Don't worry about it now. But if you know why it's a dicot, thumbs up. It's because it has these two things. Again, we'll talk about this later. So don't worry if you don't know what I'm talking about right just yet. So this is our embryonic plant, and this is what's called endosperm. And basically, it's the food supply for the embryo. The embryo is going to use this endosperm for energy to grow and turn into a sprout. And you can't really see it, but there you can just make out this coating around the outside of the seed here. And that's going to be the tough protective shell that will allow the seed to lay dormant for a long time and resist digestion, for example, until the conditions are right for the seed to sprout. So essentially, in a way, the adaptation of pollen, the adaptation of seeds is kind of a similar theme. They allow these facets of reproduction to persist in the environment much longer. Rather than requiring, for example, the presence of water. Now the last major evolutionary adaptation I want to talk about is flowers, and these are the reproductive structures of angiosperms. We're going to talk about them in much more detail when we talk about angiosperms, but the flower is one of the last major evolutionary adaptations of land plants, and it's in part due to the flower that angiosperms saw this explosion of diversification. They, in fact, saw what they saw was an adaptive radiation. So angiosperms actually are one of the most diverse groups of land plants around today, and it's in part because of the evolution of the flower. Alright, that's all I have for this video. I'll see you guys next time.
Table of contents
- 1. Introduction to Biology2h 40m
- 2. Chemistry3h 40m
- 3. Water1h 26m
- 4. Biomolecules2h 23m
- 5. Cell Components2h 26m
- 6. The Membrane2h 31m
- 7. Energy and Metabolism2h 0m
- 8. Respiration2h 40m
- 9. Photosynthesis2h 49m
- 10. Cell Signaling59m
- 11. Cell Division2h 47m
- 12. Meiosis2h 0m
- 13. Mendelian Genetics4h 41m
- Introduction to Mendel's Experiments7m
- Genotype vs. Phenotype17m
- Punnett Squares13m
- Mendel's Experiments26m
- Mendel's Laws18m
- Monohybrid Crosses16m
- Test Crosses14m
- Dihybrid Crosses20m
- Punnett Square Probability26m
- Incomplete Dominance vs. Codominance20m
- Epistasis7m
- Non-Mendelian Genetics12m
- Pedigrees6m
- Autosomal Inheritance21m
- Sex-Linked Inheritance43m
- X-Inactivation9m
- 14. DNA Synthesis2h 27m
- 15. Gene Expression3h 20m
- 16. Regulation of Expression3h 31m
- Introduction to Regulation of Gene Expression13m
- Prokaryotic Gene Regulation via Operons27m
- The Lac Operon21m
- Glucose's Impact on Lac Operon25m
- The Trp Operon20m
- Review of the Lac Operon & Trp Operon11m
- Introduction to Eukaryotic Gene Regulation9m
- Eukaryotic Chromatin Modifications16m
- Eukaryotic Transcriptional Control22m
- Eukaryotic Post-Transcriptional Regulation28m
- Eukaryotic Post-Translational Regulation13m
- 17. Viruses37m
- 18. Biotechnology2h 58m
- 19. Genomics17m
- 20. Development1h 5m
- 21. Evolution3h 1m
- 22. Evolution of Populations3h 52m
- 23. Speciation1h 37m
- 24. History of Life on Earth2h 6m
- 25. Phylogeny2h 31m
- 26. Prokaryotes4h 59m
- 27. Protists1h 12m
- 28. Plants1h 22m
- 29. Fungi36m
- 30. Overview of Animals34m
- 31. Invertebrates1h 2m
- 32. Vertebrates50m
- 33. Plant Anatomy1h 3m
- 34. Vascular Plant Transport2m
- 35. Soil37m
- 36. Plant Reproduction47m
- 37. Plant Sensation and Response1h 9m
- 38. Animal Form and Function1h 19m
- 39. Digestive System10m
- 40. Circulatory System1h 57m
- 41. Immune System1h 12m
- 42. Osmoregulation and Excretion50m
- 43. Endocrine System4m
- 44. Animal Reproduction2m
- 45. Nervous System55m
- 46. Sensory Systems46m
- 47. Muscle Systems23m
- 48. Ecology3h 11m
- Introduction to Ecology20m
- Biogeography14m
- Earth's Climate Patterns50m
- Introduction to Terrestrial Biomes10m
- Terrestrial Biomes: Near Equator13m
- Terrestrial Biomes: Temperate Regions10m
- Terrestrial Biomes: Northern Regions15m
- Introduction to Aquatic Biomes27m
- Freshwater Aquatic Biomes14m
- Marine Aquatic Biomes13m
- 49. Animal Behavior28m
- 50. Population Ecology3h 41m
- Introduction to Population Ecology28m
- Population Sampling Methods23m
- Life History12m
- Population Demography17m
- Factors Limiting Population Growth14m
- Introduction to Population Growth Models22m
- Linear Population Growth6m
- Exponential Population Growth29m
- Logistic Population Growth32m
- r/K Selection10m
- The Human Population22m
- 51. Community Ecology2h 46m
- Introduction to Community Ecology2m
- Introduction to Community Interactions9m
- Community Interactions: Competition (-/-)38m
- Community Interactions: Exploitation (+/-)23m
- Community Interactions: Mutualism (+/+) & Commensalism (+/0)9m
- Community Structure35m
- Community Dynamics26m
- Geographic Impact on Communities21m
- 52. Ecosystems2h 36m
- 53. Conservation Biology24m
28. Plants
Land Plants
Video duration:
6mPlay a video:
Related Videos
Related Practice