Bean plants are dicotyledons. This means that they have two embryonic leaves: the initial baby leaves that sprout from a seed. There is a particular leaf structure that dicotyledons, like bean plants, have. These parts of the leaf are essential for a bean plant's well being--its growth, flowering and production of pods and beans.
Leaf structure, also known as leaf anatomy, was first studied by Theophrastus of Eresus around 300BC. Theophrastus is known as the father of biology. In 1665, Robert Hooke became the first person to look at a leaf under a microscope, and the study of plant cells began. 200 years later, Gregor Johann Mendel used a type of bean--pea plants--to study genetics.
The leaves of a bean plant perform many tasks, including photosynthesis and respiration. During photosynthesis, the bean plant absorbs sunlight and converts it into energy for the plant to grow and thrive. Respiration uses the energy produced during photosynthesis to process carbon dioxide and release oxygen.
There are many types of leaves: fronds found on ferns, the sheath-shaped leaves of grasses and needle-shaped leaves of conifers. Pea plants have a leaf type known as angiosperm, which means that the plant flowers. One of the most common types of bean plants is the runner bean, which commonly has red or white flowers.
Parts of the Bean Leaf
The bean leaf consists of a variety of parts. The epidermis is the outermost layer of the bean leaf, and it regulates water and air intake. The mesophyll is the middle part of the bean leaf, where photosynthesis takes place. Veins are the final part of the bean leaf, and they consist of xylem and phloem: veins that bring water from the roots to the leaves, and that bring the energy produced from photosynthesis to the rest of the plant.
Exterior of a Bean Leaf
The exterior of a bean plant leaf is made up of three parts: the blade, margin and petiole. The blade is the part of the bean leaf that most people recognise, as it is the widest, fleshiest part of the leaf. The margin is the outermost edge of the leaf, its external border. The petiole is the point on a bean leaf where the blade and the stem join.