Basic structure of dicotyledonous stem-Sunflower stem. Inner structure of dicotyledonous stem reveals epidermis, cortex and stele. Epidermis. Epidermis is protective in function and creates the outermost layer of the stem. Epidermis is a single layer of parenchymatous rectangular cells.
Culture. Plumbago is propagated from cuttings in the summer, but you can also grow it from seed. Plant plumbago in light, sandy, well-drained soils, spacing each shrub 36 to 60 inches apart to allow room to grow. If spaced properly, blue plumbago will naturally cascade in a fountain shape.
Polyanthas an miniatures can be planted 12 to 18 apart. In areas of the country that the climate has little or no frost these distances can be 6 more on each type plant to allow for more profuse growing habits. Shrub and garden roses vary in size so an ideal spacing will range accordingly. A good rule of thumb would be to plant them as far apart as they will grow high. This would be 4 to 6 feet apart. In warmer climates you can add 6 to 12 to those distances. Climbers to be trained on an fence should be planted 8 to 10 feet apart. Climbers to be trained on a vertical up and over arbor or on a trellis or wall can be planted as close ad desired to provide good coverage.