What adaptations do seed plants possess in addition to seeds that seedless plants lack? – There are numerous additional adaptations that distinguish them from seedless plants. The gametophyte is the multicellular, haploid stage of both seeded and non-seeded plants.
Both plant groups contain vascular tissues, with angiosperm containing xylem and phloem and the remainder consisting of tracheid. What adaptations allow plants to reproduce in the absence of water? Flowers or cones, the transfer of sperm via pollination, and the protection of embryos within seeds are adaptations that enable seed plants to reproduce without water.
What are the four gymnosperm groups?
What additional adaptation do seed plants possess?
Other reproductive adaptations of seed plants include ovules, pollen, pollen tubes, and animal pollination. In seed plants, an ovule is a female reproductive structure that contains a tiny female gametophyte.
Important adaptations to (increasingly arid) terrestrial life – The following material was taken from OpenStax Biology 25.1 Early land plants could not survive far from a source of abundant water. Over the course of evolution, land plants have developed strategies to survive in increasingly arid environments.
- In many ways, nonvascular plants, or Bryophytes (liverworts, mosses, and hornworts), are physically connected to water. Their major adaptations to life on land are a waxy cuticle and structures resembling roots (rhizoids). Aside from these two characteristics, their life cycle is highly dependent on water
- they must live in extremely humid environments near water sources. They are extremely short because no mechanism exists to move water against gravity. Their gametes are not protected from desiccation, and the flagellated sperm must swim in water to find the egg in order to mate.
- Compared to nonvascular plants, seedless vascular plants (lycophytes, ferns, and horsetails) have two major adaptations: true roots and vascular tissue. In the early colonization of land, these adaptations allowed seedless vascular plants to outcompete nonvascular plants.
- True roots penetrate the soil more deeply than rhizomes, allowing for a more efficient absorption of water and nutrients.
- Vascular tissue (xylem and phloem) is composed of tube-shaped cells that transport water (in xylem) from the roots to the leaves and sugars (in phloem) from the leaves to the rest of the plant’s tissues. The adaptation of vascular tissue allowed these plants to reach greater heights than bryophytes (and thus get more access to sunlight for p hotosynthesis). Lignin, a rigid component of some plant cell walls that provides structural rigidity and allows for greater water movement against gravity, will first evolve in these groups, resulting in taller plant growth.
- Aside from these two adaptations, seedless vascular plants are still dependent on water for reproduction
- similar to Bryophytes, their sperm and eggs are susceptible to desiccation, and the sperm must swim through water to reach the egg.
By combining the strength of lignin with the phenomenon of secondary growth, gymnosperms (gingkos, cycads, and conifers) are able to attain greater heights on land (e.g. tree rings). They have two additional adaptations beyond those of nonvascular and seedless vascular plants that allow them to colonize drier environments:
- Pollen is a mechanism that transfers sperm to the egg in the absence of water. Numerous sources assert that pollen and sperm are identical, which is untrue. Pollen actually produces sperm. This topic will be revisited later in the course, so for now, just know that pollen protects sperm from dehydration and provides a means for sperm to reach the egg without water. Wind transports pollen (and consequently sperm) to the eggs of seeded non-flowering plants.
- In multiple ways, seeds protect the fertilized egg on land. Clearly, the seed is a tough physical structure that protects the fertilized egg (embryo) from dehydration. But additionally, and less obviously, the seed is a form of’suspended animation’ for the embryo, pausing development until environmental conditions are optimal for seed germination (emergence of the embryo from the seed to start growing as a plant).
Flowering plants, or angiosperms, have the most recent adaptations to terrestrial life: the flower, double fertilization and the endosperm, and fruit.
- Flowers may not appear to be an obvious adaptation to life on land, but they rely on pollinators (insects, birds, bats, and other animals) to transfer pollen (and thus sperm) to eggs. Reliance on pollinators is significantly less random than reliance on the wind, representing an important adaptation to life on land as well as co-evolution with particular pollinators.
- Endosperm and double fertilization: In flowering plants, double fertilization is a unique process in which one sperm fertilizes the egg to produce an embryo and a second sperm fertilizes a structure adjacent to the egg to produce an endosperm. Endosperm undergoes a pseudo-development in which its mass and content increase in order to provide nutrients to the embryo during germination. These concepts will be covered in greater depth later in the course.
- Fruits are any structure that aids in seed dispersal, such as something sweet that is consumed by an animal so that the seed is deposited somewhere new in the feces (along with its own fertilizer!). Thus, fruits allow seeds to colonize new territories away from the parent plant.
Flowers may not appear to be an obvious adaptation to life on land, but they rely on pollinators (insects, birds, bats, and other animals) to transfer pollen (and thus sperm) to eggs. Reliance on pollinators is significantly less random than reliance on the wind, representing an important adaptation to life on land as well as co-evolution with particular pollinators.
Endosperm and double fertilization: In flowering plants, double fertilization is a unique process in which one sperm fertilizes the egg to produce an embryo and a second sperm fertilizes a structure adjacent to the egg to produce an endosperm. Endosperm undergoes a pseudo-development in which its mass and content increase in order to provide nutrients to the embryo during germination.
These concepts will be covered in greater depth later in the course. Fruits are any structure that aids in seed dispersal, such as something sweet that is consumed by an animal so that the seed is deposited somewhere new in the feces (along with its own fertilizer!). 
The phylogenetic tree displayed below illustrates the evolutionary relationships between modern plants and the origins of adaptations in each plant lineage: Phylogeny of plants illustrating the major land plant lineages and adaptations. Image attribution: Shana Kerr
What are the adaptations that distinguish seed plants from seedless plants?
Seeds and pollen distinguish seed plants from other (seedless) vascular plants; they are two crucial adaptations to drought and reproduction that does not require water. Both adaptations were required for the bryophytes’ and their ancestors’ colonization of land.
The plants are alive:
- They evolve and perish
- They generate new people.
- They consist of cells.
- They require nutrients, oxygen, and water.
- They react to their surroundings.
Plants differ from animals in part because, with a few exceptions, they use the energy from sunlight through a process known as photosynthesis. Plant cells and animal cells share many similarities, but their structures are distinct. There are numerous types of plants.
- Plants that generate seed (flowering plants and cone plants).
- Plants producing spores (ferns, mosses, liverworts and green algae).
Seed plants have specialized structures (flowers or cones) where male and female cells join in a process known as fertilization. In a seed, a tiny plant called an embryo develops following fertilization. The seed protects and stores food for the embryo.
- Gymnosperms are coniferous plants.
- Angiosperms are flowering plants.
What characteristics are specific to plants that produce seeds?
Pollen Production Is a Characteristic of Seed-Producing Plants – Pollen production is a characteristic of seed-producing plants, as there can be no seeds without pollen. Pollen grains contain male sperm, which must fertilize an egg in a female spore to produce a viable seed.
