Plants are placed into two simple kingdom subsections: nonvascular and vascular plants. The big distinction between the two groups is that vascular plants have vascular_tissues: tissues that conduct water and dissolved food in the plant body. The vascular tissues include xylem, which moves water and minerals upward through the plant and phloem, which moves dissolved food downward in the plant.
Nonvascular plants lack these tubes, and therefore must be small and thin so that each cell can acquire its needed materials via passive_transport from the plant's surface, or from other cells within the plant that are located near the surface.
Regardless of whether a plant is vascular or nonvascular, it has structures that (1) anchor it into the soil, (2) provide physical support for its photosynthetic structures, and (3) specialize in performing photosynthesis.
The difference is that in nonvascular plants these structures are called root-like, stem-like, and leaf-like because they lack vascular tissues. True roots, stems, and leaves are those body structures that contain vascular tissues.
Highly developed vascular systems allow the production of an effective adult plant body, with sufficient reserves to allow the investment in specialized body structures used for reproduction. Good vascularization also provides for structures used to enhance dispersal of the gametes and/or zygotes (fertilized eggs).
All Gymnosperms are perennial and many live for centuries. Oldest known living organism is the bristlecone_pine (Pinus_aristata) in the mountains of California. It is approximately 5,000 years old. Most Gymnosperms are trees, but a few are shrubs and vines. Their ovules develop within a cone, which is known as a strobilus. Gymnosperms differ from Angiosperms, in part because their ovule (which becomes the seed) is not enclosed by the tissue of the sporophyll.
These pine embryo sectiond show the remains of the megasporangium , as well as a well-developed embryo. Locate the female gametophyte (reproductive tissue), cotyledons (first embryonic leaves), epicotyl (first stem), hypocotyl (first root), apical_meristem (region of rapid stem growth), and root_meristem (area of rapid root growth).
The micrographs on pages 64-65 of your Photo Atlas show the embryonic developmental sequence of Capsella, a typical Angiosperm. Please emphasize the review of figures 65D and 65E as they will most closely resemble the stages present on most of our lab microslides. You should be able to identify:
cotyledons (first leaves),
epicotyl (first stem),
endosperm (food storage tissue),
hypocotyl (first root),
root_cap (physical protection for the developing root tip) and
seed_coat (physical protection for entire seed).