Plant morphology share the same basic structure and development as leaves in other plants, and therefore cactus spines are homologous to leaves as well. This aspect of plant morphology overlaps with the study of plant evolution and paleobotany. Secondly, plant morphology observes both the vegetative (somatic) structures of plants, as well as the reproductive structures. The vegetative structures of vascular plants includes the study of the shoot system, composed of stems and leaves, as well as the root system. The reproductive structures are more varied, and are usually specific to a particular group of plants, such as flowers and seeds, fern sori,
Plant stem cell on earth, including Bristlecone Pines in California, U.S. (4,842 years old), and the Giant Sequoia in mountainous regions of California, U.S. (87 meters in height and 2,000 tons in weight). This is possible because they have a modular body plan that enables them to survive substantial damage by initiating continuous and repetitive formation of new structures and organs such as leaves and flowers. Plant stem cells are also characterized by their location in specialized structures called meristematic tissues, which are located in root apical meristem (RAM), shoot apical meristem (SAM), and vascular system ((pro)cambium or vascular meristem.) Traditionally, plant stem