Yes, most vascular seedless plants do have roots, which are essential for absorbing water and nutrients from the soil, but there are notable exceptions within this group.
Understanding Roots in Vascular Seedless Plants
The evolution of the vascular system was a significant step in plant history, enabling plants to grow taller and transport water and nutrients more efficiently. According to the provided reference, "With the vascular system, there appeared leaves—large photosynthetic organs—and roots to absorb water from the ground." This indicates that roots developed as a crucial structure alongside the vascular system, particularly for terrestrial life.
Seedless vascular plants are a diverse group that includes some of the earliest plants to possess this internal transport system (xylem and phloem) but still reproduce via spores instead of seeds. This group encompasses various types, such as:
- Club Mosses: These often have a root system originating from horizontal stems (rhizomes).
- Horsetails: Possess roots that anchor the plant and absorb water.
- Ferns: Typically have a fibrous root system growing from an underground stem called a rhizome.
These roots serve the primary functions of anchorage and the vital absorption of water and dissolved minerals from the substrate.
Evolutionary Adaptations and Exceptions
While roots are characteristic of many seedless vascular plants, evolution can lead to the modification or even loss of certain structures over time. The reference specifically highlights an example of this phenomenon: "...whisk ferns, which lost leaves and roots by reductive evolution...".
- Whisk Ferns ( Psilotum and Tmesipteris): These are a unique group of seedless vascular plants that, as the reference states, have undergone reductive evolution, resulting in a simpler structure that lacks true leaves and roots. Instead of roots, they possess underground stems (rhizomes) anchored by root-like structures called rhizoids, often living in association with symbiotic fungi (mycorrhizae) to aid in nutrient and water uptake.
This example demonstrates that while the appearance of roots is generally associated with the evolution of vascular tissue, specific lineages within the seedless vascular plants have secondarily lost these structures.
In summary, while the majority of familiar seedless vascular plants like ferns, horsetails, and club mosses have roots, it is not a universal feature across the entire group, with examples like whisk ferns being a key exception.
