Industrial Hemp vs. Marijuana
The modern mindset lumps industrial hemp in with marijuana. Although they are members of the same species (Cannabis sativa), their resulting products are entirely different from each other.
Take dogs, as an example. A beagle and a Saint Bernard are both Canis familiaris, but no one can ever say the resulting characteristics are the same.
The same can be said of the herb Coriandrum sativum, in which either the seeds or the leaves are used. The resulting products from the same plant are entirely different from each other.
If the seeds are used, it is called Coriander, but if the leaves are used then it becomes Cilantro.
So it is with the hemp plant.
Use of the leaves makes it marijuana, but the nutritional seeds are known as that – or hemp nuts.
In addition, when Cannabis sativa is grown for its fiber and edible seed, it is a stalky crop with only a few leaves remaining on top; but if marijuana is the desired result, the crop has to be grown differently. Therefore, it becomes bushy with many leaves.
Another difference is that marijuana contains substantial percentages (3-9%) of the chemical tetrahydrocannabinol, or THC. Industrial hemp may contain negligible amounts of THC (less than 1%), but usually there are only trace amounts, if that.
These facts are scientifically verified through the use of gas chromatography. Smoking industrial hemp would cause a headache rather than the preferred ‘high’ sought in marijuana. In fact, the more that industrial hemp is smoked, the bigger the headache!
How the two are planted is another difference between the two. Stands of industrial hemp are densely planted at a rate of 300-500 plants per square meter. Hemp plants are very tall and range in height from 6 to 16 feet. They also have few leaves and no branches. By contrast, marijuana is planted at a rate of 1 or 2 plants per square meter with each becoming quite bushy, with lots of wide branching to promote flowers and buds.
Canadian researcher, Ernest Small, wrote a two-volume study entitled The Species Problem in Cannabis, in which he summarized the distinction between the two plants.
See also What Happens When You Cross Hemp and Marijuana
Botanical Descriptions
Stem Layers: The various layers of the hemp stem include the following:
- Epidermis layer is the thin outside protective layer of plant cells.
- Cortex layer is a thin layer of walled cells that has no fiber, but does contain chlorophyll.
- Phloem or parenchyma layer contains short cells that have chlorophyll and long cells that are bast fibers.
- Cambium layer is the growth area which produces hurds on the inside and bast and bark on the outside. Although this is the differentiation layer, it is also an abscission layer where fiber and hurds separate during the retting/breaking process.
- Pith layer is composed of thick, woody tissue used to support the plant. The product from this area is called hurds which comprises 60-75% of the total mass.
- Hollow core is the center of the plant and exists throughout the stem except at the joints.
Fiber Types: Total fiber content is approximately 25-35% of the stem dry matter, depending on the variety.
- Primary bast fiber – long and low in lignin
- Secondary bast fiber – intermediate and high in lignin
- Libriform – short and high in lignin
According to Dr. Ivan Bocsa, industrial fiber varieties can be classified into two basic sexual types: monoecious and dioecious. Monoecious varieties have both male and female flowers on each plant, while Dioecious varieties have entirely separate male or female plants.
The dioecious trait is the natural condition for hemp while monoecism occurs infrequently in hemp populations. The incorporation and stabilization of monoecism in fiber hemp call for the skills of a competent plant breeder.
It was a Russian hemp breeder who first recognized the utility of monoecism in solving two of the plant’s critical problems: low seed yield and uneven maturation of the sexes.
Monoecious hemp varieties require yearly selection to prevent the increasing return of separate male and female plants (dioecism) over successive generations of open-pollinated seed production.
Also, because seed from successive reproductions gives progressively lower seed yield in the dual-purpose (fiber and seed) monoecious crop, it is customary to label monoecious hemp seed according to the number of generations that have been grown since a new supply of seed was obtained from the breeding source.
Fiber Cells
In a cross section, fiber cells are easy to differentiate from the adjoining bast elements and the pericambium (primary cell tissue). Fiber cells rarely occur individually but are generally incorporated into fiber bundles. The shape of the fiber bundle can have a round, oval, elliptical, or rectangular cross-section.
Since stalks grow from the inside out, on older plants, fiber bundles are located toward the outside. Individual fiber cells, called fundamental cells, are held together in bundles by binding substances consisting mainly of pectins. The fundamental task of the processing industry is to break down the fibers by biological mechanisms or chemical processes (called retting).
The cross sectional shape of individual cells is 3- to 7-sided. Fibers are pressed tightly together during the secondary growth stage of the rest of the stalk, which alters their original circular shape. The ends of the fiber cells are rounded off but often show a forked-shape branching.
The most important component of the fiber is cellulose. Fiber bundles also contain hemicellulose, pentosans, pectins, and lignins, which are decomposed by bacteria during retting. However, cellulose is not decomposed as easily by these processes; and, therefore, relatively clean fiber bundles can be obtained by mechanical fiber processes.
Stalks
Hemp stalks are dependent upon two things: the sex of the hemp plant and how closely they are planted together. Male stalks are generally 10-15% taller than female stalks, even though the female vegetative period is 6-7 weeks longer. Stalks planted in close proximity to each other average 4-8 inches and increases as available area increases. Male plants also have thinner stalks while female stalks are shorter and thicker.
Historically, farmers pulled up male plants on their small plots separately from the female plants and used the male plant fibers for fine linens (bedding, hand towels, and clothing). The female plant fibers were used to make coarser fabrics (bags and tarp). Today, precise tests reveal that male plants surpass female ones in all qualitative parameters except tensile strength. Common fiber hemp in a mixed plot takes a median position between both sexes. In terms of quality, its fibers are closer to male fibers than female fibers.
When separated from the roots and leaves, the stalk constitutes about 65-70% of the total mass of a fully grown plant. If fiber hemp is densely sown, the leaves fall off during the developmental phase and tiny calluses form at these points. The crop loses most of its leaves, and fiber hemp does not have many branches. However, the area available for one plant to expand is two square feet; meaning roughly five plants per square meter or a 3-foot square plot.
The hemp stalk consists of wood and bast tissue.
- Bast tissues are the most important tissue for hemp cultivation and processing. Bast tissue forms the exterior layer of the stalk and is composed of phloem, bast parenchyma, bast radial parenchyma, and bast fibers. Bast tissues function as the plants transport system, carrying the products from photosynthesis from the leaves to the roots. Then it turns around and carries nutrients, taken up by the roots, back to the leaves. However, the main function of the bast cells is not the transportation of nutrients, but rather to reinforce or strengthen the stalk. These fiber cells, in contrast to wood fibers, do not provide vertical strength as much as tensile strength and break or torque resistance. In bast tissue, groups of fiber cells whose strong outer cell walls have thick layers of cellulose are formed. Hemp is cultivated for these fiber cells and generally viewed as an integral component of the bast tissue even though they are located outside between the cortex and the bast. Bast tissue consists of 65% cellulose, 15% hemicellulose, and 4% lignins.
- Wood tissue consists of tracheids, wood parenchyma cells, and wood fibers, which transport water and nutrients. The wood tissue forms the hurds, which contain 37% cellulose, 35% hemicellulose, and 21% lignins. Wood fibers are responsible for the vertical strength of the stalk. The length of the wood fiber cells does not exceed 0.02 inches. Wood fibers are significantly stiffer and less flexible than bast fibers.
Leaves
Hemp has finely formed pinnate leaves, with each containing several individual pinnations called ‘fingers’ or ‘leaflets’. Their numbers are determined by three factors: variety, age of the plant (since the first true leaves have only one leaflet which increases as the plant continues to develop), and the position of the leaves on the stalk. (During the vegetative stage, leaves grow opposite one another [decussate]; but later changes to a staggered position [alternate] at the beginning of the generative stage.)
The leaves are supported by stiff leaf stems called petioles. The leaf surface is covered with numerous top hairs and a few glandular hairs capable of excreting varying amounts of THC in the resin. Irregularly shaped leaves are common and develop from fused leaflets, from a dual-leaf formation, or from chlorophyll defects resulting in different colors (teratogenic formations).
Flowers
Male flowers develop in pairs and consist of a simple calyx (floral sheath) with five yellowish-green petals. When viewed from above, open male flowers appear star-shaped. The number of male flowers depends on the spacing of the plants. Hemp is cross-pollinated and wind-pollinated. The pollen from the female flowers is dry and floury and forms dense clouds during flowering season. Pollen clouds can reach altitudes of 20-30 m (65-100 feet) and travel as far as 7-8 miles. A single male hemp plant of about 10-13 feet high and planted in a wide row, can produce about 30-40 gm (1-1 ½ oz) of pollen.
Female flowers are very short and tightly clustered. They usually consist of one green, single-leaf calyx that surrounds the hidden ovary containing one seed. Only two thin pistils (fused style and stigma) protrude from lateral slits. The flowers are initially white, but later become crimson red. Female flowers are very inconspicuous. Even at close range they are hard to recognize.
When pollination is late, or if there is a deficiency, the pistils reach an unusual length and turn bright white. In varieties with a high THC content, the glandular hairs on the pistils and surrounding calyx excrete a sticky resin used to produce hashish. The whole dried female flower is described as marijuana and harvested from the end of flowering to initial seed growth.
In some countries, monoecious hemp is cultivated and its flower structure does not differ from that of dioecious hemp. However, the location of the inflorescences is different with the male flowers which are located in a whorl on the stem of the primary branches. Female flowers are situated on the tops of primary branches. Monoecious hemp has fewer male flowers and less pollen than the dioecious hemp and also fewer female flowers.
Seeds
Hemp seeds are not true seeds, but rather nuts. Each consists of a dry, closed achene that contains a single seed surrounded by the pericarp (the very thin first husk that has net-shaped veins) and sometimes still surrounded by a leaf.
Hemp seeds are either spherical or elliptical. The color varies from a light grey to brown and is often marbled. This is not a genetic characteristic of the pericarp, but rather represents the coloured imprint of the surrounding bracts at harvest. This is not a theory but a fact, since the marbled pattern can be removed by washing or rubbing.
Healthy seeds, not older than one or two years, have a bright luster. Old, moldy, or diseased seeds will be dull and will not germinate.
The hemp seed consists of two cotyledons (seed leaves) that are rich in reserve substances, a rootlet, and a thin, undeveloped endosperm containing starch. The cotyledons and rootlets are rich in oil, roughly 30-32%. The oil dries well and could be used for paints, lacquers, or varnishes; but is too expensive for these purposes and cannot compete with flax, canola, and sunflower oils. However, its composition makes it an excellent nutritious, edible oil. Hemp seed oil is expensive because much less oil is produced compared to canola or sunflowers.
Hemp seeds rapidly lose their ability to germinate, which is at 95% in the year of harvest but only 80% in the following year. After two years, seeds are no longer suitable for sowing unless kept at temperatures of 2-3°C (36-37°F) with minimal humidity. If seeds are frozen at -12°C (10°F), the germination potential rises to 6 or 8 years with no loss of quality. The oil can also be frozen to prevent rancidity.
Roots
The hemp plant has well-developed primary roots from which numerous branched secondary roots form. The primary root can reach depths of six to eight feet while the secondary roots can extend more than two feet. The depth of the root zone primarily depends on the physical and chemical characteristics of the soil. For example, the primary root reaches deeper (6.5 feet) in crumbly soil with a high mineral content than in marshy soil where most of the root mass is located in the topsoil at depths of 12-20 inches. In marshy soil, the primary root merely reaches a depth of one to two feet, with the largest root mass located in the top soil at a depth of four to eight inches.
Because of its shorter vegetation period, the root structure of the male plant is not as strong as that of the female. This depends mainly on the site but also on the method of agriculture. The root structure of the hemp is poorly developed compared to that of other economically significant plants, which explains why hemp requires high amounts of nutrients and water.
