Coleus shoot tip
Coleus shoot tip Primordial leaf
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.
The Angiosperms (flowering plants) are divided into two design categories, based in part upon the placement of their vascular tissues. The two categories are monocotyledons (monocots) and dicotyledons (dicots).
This slide shows the growth region of a Coleus shoot tip, which is known as the apical_meristem. Around the leaf buds associated with the apical growth area are numerous surface area extensions called trichomes.
Trichomes are surface structures (such as epidermal_hairs), which are derived from epidermal cells. Trichomes can increase surface area for absorption of water, help secure the plant, inject poison, create a rough surface that animals cannot land on, create a baffle to control air flow, or provide shade.