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The leaf-like organs of bryophytes (e.g., mosses and liverworts), known as phyllids, differ greatly morphologically from the leaves of vascular plants. In most cases, they lack vascular tissue, are a single cell thick and have no cuticle , stomata, or internal system of intercellular spaces.
Variation in leaves from the giant ragweed illustrating positional effects. The lobed leaves come from the base of the plant, while the unlobed leaves come from the top of the plant. Although plants produce numerous copies of the same organ during their lives, not all copies of a particular organ will be identical.
The epidermis is the outermost cell layer of the primary plant body. In some older works the cells of the leaf epidermis have been regarded as specialized parenchyma cells, [1] but the established modern preference has long been to classify the epidermis as dermal tissue, [2] whereas parenchyma is classified as ground tissue. [3]
Organography as a scientific study starts with Aristotle, who considered the parts of plants as "organs" and began to consider the relationship between different organs and different functions. In the 17th century Joachim Jung, [ 1 ] clearly articulated that plants are composed of different organ types such as root, stem and leaf, and he went ...
Surface of an organ facing away from the organ's axis, e.g. the lower surface of a lateral organ such as a leaf or petal. [2] Contrast adaxial. abort To abandon development of a structure or organ. [3] abscission Natural shedding of an organ that is mature or aged, as of a ripe fruit or an old leaf. [4] abscission zone
The lobed leaves come from the base of the plant, while the unlobed leaves come from the top of the plant. There is variation among the parts of a mature plant resulting from the relative position where the organ is produced. For example, along a new branch the leaves may vary in a consistent pattern along the branch.
Leaf – the photosynthetic organ of a plant that is attached to a stem, generally at specific intervals. Leaf axils – the space created between a leaf and its branch. This is especially pronounced on monocots like the bromeliads. Leaf buds – buds that produces leafy shoots.
Fourteen days later, leaves have developed (right). Shoot apical meristems are the source of all above-ground organs, such as leaves and flowers. Cells at the shoot apical meristem summit serve as stem cells to the surrounding peripheral region, where they proliferate rapidly and are incorporated into differentiating leaf or flower primordia.