Final answer:
Megasporangia and microsporangia in Isoetes are located at the base of their leaves, and they have a specialized stem called a corm. Rhyniophytes are significant as early vascular plants with fossils found in the Rhynie chert of Scotland.
Step-by-step explanation:
Isoetes Sporangia Location and Specialized Stem
- The megasporangia and microsporangia of specimens of Isoetes, commonly known as quillworts, are located within the base of their leaves. These sporangia are produced in structures called sporophylls. Isoetes is associated with a specialized stem known as a corm, which is a short, vertical, swollen underground plant stem that serves as a storage organ to enable the plant to survive winter or other adverse conditions.
Significance of the Rhyniophytes
- The Rhyniophytes are significant as they are among the earliest known group of vascular plants, providing insights into the evolution of land plants. Fossils belonging to the Rhyniophytes were found in the Rhynie chert of Scotland, which is an exceptionally preserved fossil deposit dating back to the Devonian period, providing valuable information on early terrestrial ecosystems.