Plant growth is primarily based on two conditions: Genetics and environmental conditions. I havent taken either into account whilst writing this, and this another extremely in depth topic in itself. The growth rate of certain varieties can vary within and particular geographical race and genetic makeup of the strain, the growth curves are always characteristic of the varieties. Plant development is dependant upon temperature and the availability of nutrients and water.This guide is not a step by step grow guide, it is merely a reference for information on the Cannabis plant anatomy. I hope it helps and educates others, and if there is anything you would like to add, please feel free to mention it!
Generally with most Cannabis plants you end the vegetative period by altering the light cycle. The vegetative cycle can be divided into different phases:
The Germination Phase: This involves the germination of the seed and lasts until the firat pair of true leaves on the germinating plant reach the size of the cotyledons and are capable of photosynthesis.
The 'Slow Growth" stage: Is started from the initial appearance of the first set of true leaves, and lasts approximately until the growth of the fifth set of leaves.
The 'Rapid Growth" stage: Which lasts from the start of the Slow Growth stage up until the formation of flowers.
The Period between the growth of flower buds in the leaf axis and the time when the first flowers open, after which growth gradually slows.
Flowering: Extends from the time when the anthers on the first male flowers open and release their pollen to the time when the flowers in the upper third of the inflorescence open and their pollen is released.
The growth of the achene: Lasts from the initial swelling of the seed embryo to the maturation of the first seeds.
Under adequate conditions, roots begin to form after 24-48 hours after planting the seed. After this the cotyledons will appear, from which the hypocotyl develops. The next process is the growth of the epicotyl. Concertedly the primary pair of first leaves will develop. Growing oppositely oriented, sets of pairs of leaves continue to grow along the epicotyl and then eventually after the cotyledons nutrients are expended, the cotyledons dry out and the plant starts to live autonomously. It is very important that a grower does NOT remove the cotyledons whilst the plant is growing, as this is a very valuable nutrient resource for the seedling, and may result in problems with the growth of it. After approximately two weeks (Strain and environmentally dependant) the stem segments become longer and the first axial limb buds will begin to form and branch out.
Now, you might notice that the leaves are starting to differ from eachother in the size, and the amount of individual 'fingers' or pinnations, also known as leaflets. The number of leaflets are determined by three antecedent factors. Variety and genetics of the strain, age of the plant and the position on the stem. In the vegetative phase the leaves will grow decussate, their position changing later to an alternate node positioning. Each leaf is supported to the main stem via petioles, which above these petioles grow the axial limb buds. Odd shaped leaves are common on some plants, and develop from fused leaflets, from a dual-leaf formation, or from chlorophyll defects, resulting in leaflets with teratogenic formations.
The male flowers develop in pairs at the petiole nodes (intersections) of the inflorescence. The male flower consists of a simple calyx (floral sheath) with five petals that are yellowish-green. The petals surround five stamens that consist of anethers (pollen sacs) suspended on thin filaments. The anthers have an elongated prism shape prior to maturation and turn light-yellow following maturation. The open male flowers appear star-shaped when viewed from above. The number of male flowers primarily depends on spacing of the plants. Fiber help plants having fewer branches that are thinner and longer have relatively few male flowers because inflorescences develop only on the tip of the plant. One secondary branch of a widely spaced male plant has considerably more flowers than another in a dense crop. Cannabis is a crop-pollinated, wind-pollinated plant. The pollen is dry and floury, and forms dense clouds during the flowering period. These pollen clouds can reach an altitude of 30 meters and travel as far as 10km.
The secondary branches of the female inflorescece are very short, bearing tightly clustered female flowers. Therefore the female inflorescence is dense and club-shaped after pollination and during harvesting. The female flower consists of a green, single leaf calyx that surrounds the 'hidden' ovary, which has one seed. Only the two thin pistils protrude from lateral slits. They bear dual-forked stigmas that are initially white but later become a red colour. The end of the flowering period sees the glandular hairs on the pistils and the surrounding calyx ecrete sticky resin.
Epicotyl - The stem of a seedling or embryo located between the cotyledons and the first true leaves. http://dictionary.re...arch?q=epicotyl
Cotyledon - A leaf of the embryo of a seed plant, which upon germination either remains in the seed or emerges, enlarges, and becomes green. Also called seed leaf. - http://dictionary.re...rch?q=cotyledon
Hypocotyl - The part of the axis of a plant embryo or seedling plant that is below the cotyledons. http://dictionary.re...rch?q=hypocotyl
The attached images are properties of their rightful owners and I've asked permission to use them from most of them.
Edited by Nath, 10 August 2004 - 08:59 AM.