These plants complete their life cycle from seed to flower to seed in one year.
Some herbaceous plants are annuals, like beans and pansies, where the whole plant dies over the winter. We will explore plants with secondary growth in a different lesson. Production of xylem and phloem from cambium cells is called secondary growth and is typical of woody perennial plants. Cambium is a meristem in the vascular tissue positioned between the xylem and phloem that continues to produce new xylem cells toward the interior of the stem and new phloem cells toward the exterior. Branching of the shoot is initiated at nodes where there are axillary buds containing axillary meristems that grow into branches.Ĭontinued growth of the stem in diameter, like you find in a tree where the trunk and branches increase in diameter each year, requires an active lateral meristem called the cambium. Stems of herbaceous plants typically do not thicken very much and rely instead on branching to grow laterally (although there are exceptions like sunflower and tomato whose stems do thicken noticeably). Herbaceous plant shoots grow in length and diameter in the same way that roots do: the apical meristem at the tip of the stem produces new cells and then those new cells enlarge in length and volume in the region of elongation just behind the meristem. Herbaceous plants are plants whose above-ground plant parts die back to the soil surface at the end of the growing season. Introduction to stems Notice this image of a palm tree because it will come up again later. Describe the functions of some of the specialized cells in the stem.Distinguish monocot and dicot stems based on the arrangement of the vascular bundles.Identify the tissues that are initially produced by apical meristems and the cells into which they eventually mature.Discuss how stems grow by elongation and by increasing their girth or diameter.By the end of this lesson you will be able to:
0 kommentar(er)
