By Robert Bergman, ILoveGrowingMarijuana.com
The Plant Kingdom is the foundation of almost every single ecosystem on the face of the Earth. Without plants, there would be no animals— no insects, mammals, or birds. No humans. Animals (humans included), depend on plants for food. Plants, however, are not held down by the same restrictions. They transmute their food through the process of photosynthesis, requiring only water, C02, and sunlight. Plants of the Cannabis genus are no exception. But what characteristics identify cannabis? How do the mechanisms of photosynthesis function within the plant itself? These questions are simple but significant. In order to properly grow marijuana, we must first understand how it works, down to each constituent part.
In this quick educational summary, we will break the Cannabis plant down into five parts:
– Flowers– Foliage– Stems– Root system– Tissues
The Role of FlowersLike other members of the plant kingdom, it is the flowers of the Cannabis plant that serve as reproductive organs. Cannabis usually has imperfect flowers, meaning that plants are separated into male and female. Male flowers contain stamen, which are composed of a thin tube-like filament capped by a pollen covered anther. Female flowers have pistils, with a pillar-like stalk (called a style) ending in a stigma. The stigma is usually sticky or feathered so that it can catch grains of pollen.
Cannabis plants reproduce by getting pollen from the stamen of a male plant to the pistil of a female. In plants, this style of reproduction is known as pollination. In addition to being vital for reproduction, it is the cannabis flower that contains THC and CBD, the two primary active ingredients, and the reason the plant is smoked. In order to maintain high levels of these active ingredients, and thus maintain a high-quality product, it is important not to let the female flowers be fertilized. After fertilization, a female plant begins to put resources into the production of seeds. Unfertilized, a plant will devote resources to producing more calyxes, teardrop nodules that typically contain high concentrations of trichomes. Those are the glands that secrete THC and other cannabinoids.
Foliage (Leaves)The most important part of every plant is the leaf, where photosynthesis occurs, and therefore the source of food. Photosynthesis is conducted by chloroplast cells, which gather sunlight and store it as ATP.
A plant leaf is comprised of a petiole (stalk), mesophyll and veins. Mesophyll is the meat of the leaf, where the cells with chlorophyll capture sunlight and convert it with CO2 into energy. Veins extend from the very tips of leaves all the way down to the roots, comprised of xylem and phloem. The xylem transports water and phloem transports sugar (energy). Stomata are located on the underside of the leaf. These function as the locks to the interior of the plant, opening and closing at different times to allow for the transmission of CO2, oxygen and water vapor.
From a practical standpoint, leaves do better in sunlight. They will grow to be healthier, more robust, and more full of chlorophyll. More chlorophyll means more sugar, which means more energy, which means a better plant. Leaves in shade have a much lower threshold for sugar production than leaves in sunlight.
Nodes are the intersection points of leaf bundles.One way to help ascertain the health of a plant is to examine the nodes. The first node of a plant always sprouts single-fingered leaves, the next three-fingered leaves, the next five-fingered leaves and so on. The better the plant’s environment, the more fingers the leaves will have, and the healthier the plant will be. Keep this in mind while you are pruning. Pruning can be advantageous, but it is important to know what you are pruning and why.
Because of the way leaves intake carbon dioxide and output oxygen, it’s important to note that the air directly surrounding your leaves might have a different temperature or humidity than the rest of the air in your greenhouse or growing environment. In order to help maintain a more accurate control over the environment, be sure to install fans to maintain proper air flow.Sturdy Healthy StemsThe stem is the primary structural axis of a plant. This is the highway over which nutrients and water are transported throughout the plant, as well as what keeps it standing straight and reaching for the sun. As discussed earlier, leaves meet the stem at the node, whereas the rest of the stem (between nodes) is known as the internode. The height of a given plant is determined by the number and length of its internodes. Remember, once a plant begins to flower, it produces buds, and the number of internodes will not change.
Like the leaf, the stem contains xylem and phloem, which run all the way down to the root. Xylem transport water and minerals from the grasping roots all the way up to the newest leaves, bringing it all up from the soil. Originating in the leaves, the phloem transports sugar and energy all over the rest of the plant.
A solid stem is essential for any plant, but especially for cannabis. A thick stem both maximizes the efficiency of energy transportation and also ensures that the plant is sturdy enough bear a harvest of dense buds without falling over. One thing a grower can do to help create a sturdy stem has to do with air flow— make sure a fan is always blowing on the plant (not too hard, especially for a young plant). This will cause the plant to thicken its stem in response to the stimuli as it grows.Contained Root SystemsWhat humans imagine when they think of plants is usually just the tip of the iceberg. With a wild cannabis specimen, for example, only half of it is visible. Underground, a root system extends tendrils out beneath the visible stem, sometimes reaching the size of the rest of the plant itself. These extensive root systems are what allow plants to survive droughts and dry times, as well as reach out more widely for nutrients in the soil. The good news— a cultivated, domestic plant can survive with a denser, smaller root system. A cannabis plant will thrive in a pot or hydroponics system, as long as the grower is careful to provide it with all the water, light, and nutrients it requires.
Roots absorb water and nutrients, keep the plant safe in the soil, and store extra nutrients. A healthy root tip is white and covered with tiny hairs. If the tips of your roots are brown, it’s probably an indication of an unhealthy plant. If this is the case, you might want to double-check the soil levels, or see if you can find any symptoms of root disease.
Evaporation is the foundation for water and nutrient uptake in a plant. Extra water is evaporated through the stomae in the leaves while, below the ground, water presses up against the roots and creates pressure. The combination of root pressure below and evaporation above create a suction system in the plant that helps promote the flow of nutrients and water from the bottom to the top. Download my free marijuana grow guide for more information about growing marijuana at this linkPlant Growth and TissuesThe sum growth of a plant occurs through cell division and cell elongation. Division is when the plant cells split apart and create copies of themselves, while elongation is when the cells expand outwards and become bigger. The most cell division in a plant occurs at the crown, the tips of the roots, and at the fringes of any leaf nodes. If a plant is growing at all, it means that cell division is occurring in these areas, often at astounding rates. If you had the patience to watch a plant for a day, you could actually see it grow.
New cells created through cell division then undergo cell elongation and absorb water from the xylem and swell up to significantly larger sizes. A healthy plant being cultivated in a well- provided for environment can easily grow up to 3 inches in a day.
New cells start out being unspecialized— which means they can grow to meet a variety of needs for the plant, depending on what’s required. For example, a newly divided cell at the end of a petiole might become a leaf cell, one of the building blocks of photosynthesis. There are many types of cells, which we can organize into groups of tissues. To make things simple, we can divide cells into three primary groups: ground, vascular, and dermal tissues.
Most of the cells of a plant are ground cells, called parenchyma. These are the functional parts of an organism. For example, leaf cells are made up primarily of parenchymal ground cells, with the exception of the stomata and the veins.
The next set of tissues are the cells systems responsible for transportation of nutrients and water within the plant— vascular tissue. Xylem carries water and minerals up from the roots to the rest of the plant, while phloem carries the products of photosynthesis from the leaves to anywhere else they’re needed. Sugars produced in the leaves, for example, are required for energy in other parts of the plant. Vascular tissue is what makes it all work.
Finally, the external outer layer of plant cells— the dermal tissue. This is the protective layer, which guards against pests, parasites, high heat, and cold. The dermal tissue includes cell wall, waxy outer layers, and also the stomata, the locking door mechanisms of the plant, which allow it to breathe in and out, absorbing CO2 and evaporating water.