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.
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.
The Gymnosperm's sterile_bract is a physical support structure for the ovule, which consists of the mature megasporangium, megaspore_mother_cell, integument and micropyle (an entry point for sperm cells that travel through the pollen_tube). The scale will assist with wind distribution of the mature fertilized ovum.
The male microsporophyll_tissue is asexual and provides physical support for the microsporangia. The microsporangia are chambers containing pollen_sacs, which produce the sperm and pollen_grains.
Pine pollen structure includs wings (for wind distribution), a tube_cell and a generative_cell. The tube cell contains a nucleus (tube_cell_nucleus) that controls the development of the pollen_tube. The generative cell contains a nucleus (generative_nucleus) that monitors the production of haploid sperm cells.
Pollen_tubes grow from pollen_grains and safely convey sperm to their "tsrget area".