Bud Botany

In our monthly Homegrowing with the CGC newsletter, we cover botany terms and concepts related to growing Cannabis at home. Here’s what our resident botanist, Mary Dudley, has shared in past editions!

Calyx

A calyx is a part of a flower, specifically the outer whorl of sepals. Sepals are the protective, leaf-like structures that enclose and protect the flower bud before it blooms, and the calyx collectively refers to all the sepals of a flower. Its main function is to protect the developing flower bud and provide support for the petals when the flower is in bloom. It also forms the protective foundation for the reproductive parts of the plant. The calyx can vary significantly in appearance and structure across different plant species. An eggplant is an example of a plant that has a persistent calyx.

Cuttings & Clones

What’s up with cuttings & clones? A cutting is a clone, which means it's a method of asexual reproduction that results in an exact genetic copy of the mother plant. When we talk about the ability of Cannabis plants to produce clones from cuttings, we're referring to her ability to grow new plants from pieces of leaves and stems.

New roots are grown with energy captured from existing leaves, so it's important that your cutting has a few leaves that can continue to photosynthesize. Ideal cuttings have at least three nodes (the spots on the stem where new leaves form). This allows for one bottom node to produce new roots and two top nodes to retain leaves.

Use a pair of sharp scissors or pruners to remove the cutting from the stem, then remove the leaves from the bottom node. Submerge this node in water, soil or a rooting cube. New roots will form from it because masses of undifferentiated cells are centered at plant nodes and can develop roots where leaves once grew. Many plants can take advantage of this form of reproduction.

Fan & Sugar Leaves

Healthy green leaves are essential for plants as they photosynthesize and produce sugars used by roots, stems and buds as they grow. The cooler temps and decreased sunlight trigger the decay of green chlorophyll in plants, allowing the other pigments to be more visible.

Mature Cannabis leaves come in two main forms: fan leaves and sugar leaves. The sugar leaves have all my attention as I use my loupe (described in Tool Talk below) to assess when the trichomes have matured, signaling harvest time. My fan leaves have begun to lose their green hue as the buds reach maturity, turning yellow and curling up or, in the case of OG Kush, showing off the signature purple seen in photos. While this type of leaf change would be alarming in earlier growing stages, it's totally normal during the late flowering stage. For more details on Cannabis leaves, check out this article.

These fan leaves I will wet trim and feed to my rabbits and chickens. The sugar leaves I will dry trim and use for infusing butter and oil to make baked goods and topical ointments.

Lollipop Pruning

Pruning is always a source of conversation amongst gardeners new and experienced alike. As I searched the internet for photos of inspiration during my first crop, I kept seeing images of plants that seemed to have been browsed by small herbivores, totally defoliated from the buds down.

At first I thought this was the result of a specific strain adaptation or characteristic. When sitting down with Jordan at the Fab Ferments tap room, we chatted about our affinity for strong root systems, and he sent me some pics of previous grows. I noticed the signature look of those defoliated stems, and we started chatting about lollipop pruning on Cannabis plants.

In order to properly “lollipop” a plant, growers remove all growth on the lower parts of the stems, essentially removing any parts that are not in full sun/light range. This technique has been very useful to growers as they seek to increase yields.

Pest Management

Healthy plants are less susceptible to pests, and the key to helping plants stay healthy is to make frequent observations and follow up on any abnormal signs with appropriate treatment. When we inspect our plants for any male flowers, opportunities for pruning or low stress training, the development of cloudy trichomes, or to ensure they have enough moisture, we should also be checking for leaf damage, mottling, webbing, insect excrement and so on.

A bite mark on a leaf can be a sign of a caterpillar, which may continue to damage foliage and tunnel into buds. Another way to notice caterpillars is by their excrement, which looks like small black dots as they stick on the leaves and buds. An infestation of spider mites will result in thin spiderwebs surrounding buds and leaves will have a blotchy look. There are more detailed photos on this website if you want to dig deeper.

Photoperiod vs. Autoflowering Strains

Cannabis strains that require a reduction in day length to initiate the flowering phase of their life cycle are known as photoperiod strains. They allow for control over the timing of flowering so growers can continue to take cuttings from plants and maintain them in the vegetative stage as they grow large enough to produce a decent harvest.

In contrast to photoperiod plants, autoflowering strains do not depend on the length of day and instead complete their entire lifecycle as they mature in a single season. They can be a fun option for those looking to have a Cannabis plant nestled in with the rest of their houseplant collection and not worry about precisely controlling the amount of light exposure.

How were these autoflowering plants first discovered? The autoflowering trait is recessive and is found in a particular species of Cannabis known as Cannabis ruderalis. The other two common species are Cannabis sativa and Cannabis indica. All autoflowering plants express a recessive gene from Cannabis ruderalis, making most of the seeds available for growers hybrids between two or all three of these Cannabis species. (Time to dust off those biology lessons and remember your Punnett squares! For a refresher, check out our Botany Bistro archive, which includes three sessions on plant breeding and genetics.)

How did this trait develop? The initial range of Cannabis ruderalis was modern-day Russia, much farther north than the typical range of Cannabis indica in Asia. These plants had to contend with climate pressures favoring plants that were able to flower depending on age. For more info, check out this video.

Pollen & Seeds

Most of us have no desire to produce seeds in our homegrow, and the threat of drifting pollen keeps us awake at night. Cannabis sp. can be monecious (hermaphroditic) in some instances, but the majority of us are striving to grow dioecious plants, which maintain separate male and female parts on separate plants. The seeds I grew were feminized, but I still had to be on the lookout for male flowers and be ready to destroy on sight!

Why was I so against these little banana-shaped flowers invading my grow space? They produce clouds of pollen that drift on small breezes for hundreds of miles. Once this pollen lands on a female flower, it will initiate the growth of seeds. Because the production of seeds takes a lot of energy, it reduces the development of cannabinoids and terpenes—which is why I'm not currently interested in allowing any pollen to develop around my girls.

Storage

The way we store mature Cannabis matters. It is a dehydrated herb and will lose potency over time and with exposure to the elements. The culinary herbs in my pantry also have a shelf life; the recommended storage of herbs is typically a year. I'm willing to bet, though, that most of us have a few jars of oregano, bay leaves or savory that have been collecting dust for several years in our kitchens. I can guarantee you that I have some random herbs I received as a wedding gift more than a decade ago…so I have cleaning to do!

To extend the life of our precious herbs, including Cannabis, a best practice is to store them in airtight containers that are kept in a cool, dry, dark place such as a cupboard or pantry. If you come across a stash that's been hiding for a while, use your sense of smell to determine if those terpenes are still active. If you smell what you expect, that’s a good sign it's still usable. If the smell is faint or you smell something uncharacteristic (which could be a sign of mold), it’s time to put that herb into the compost and thoroughly clean your jars.

Terpenes

When I was young and my mother would start to lay out her oil paints and brushes, I knew a familiar smell would soon take over our kitchen. The jar of yellow liquid was a signal for my sister and me to escape to the backyard for a while as our mother tinkered with her art supplies. The jar held turpentine, and all I knew was that I needed to get out of sight before it became my job to clean bristles and prep canvases.

Fast-forward three decades and I hear a friend mention “terpenes” as they describe a Cannabis strain. A little part of my memory jogs, and I wonder if these two things are connected. Indeed they are! The terpenes found in turpentine are what allow it to thin paints, along with a myriad of other uses.

The chemistry of terpenes is fascinating, and their properties not only produce aromas but are crucial to biological processes. Essential oils used for aromatherapy and antibacterial purposes are taking advantage of terpenes. There are 20,000 terpenes identified in the natural world, hundreds of which can be found in Cannabis plants.

The cooperation of terpenes with cannabinoids relays a powerful medicine termed the “entourage effect.” Terpenes are found mainly in the trichomes of unfertilized female Cannabis flowers. A few common terpenes you will encounter in Cannabis plants include myrcene, caryophyllene, limonene, linalool and that turpentine partner pinene. Myrcene gives off a fruity, earthy scent and can be calming and relax sore muscles. Caryophyllene smells spicy like cloves and can relieve pain and ease gastrointestinal stress. Limonene produces a fresh lemon or citrus aroma and can reduce acid reflux. Linalool gives off a lavender scent, which is calming. Pinene has been studied for its potential benefits in memory retention and as an anti-inflammatory. It has that timeless smell of pine sap, and its ability to recall specific moments from my childhood speaks to the power these compounds hold to unlock a world of possibilities for our health and wellbeing.

Trichomes

The word trichomes originates from Ancient Greek τρίχωμα (tríkhōma) 'hair'). These small structures can be found on plants, algae, lichens, and certain protists. They are very diverse in structure and function including hairs, glandular hairs, scales, and papillae. A covering of any kind of hair on a plant is an indumentum, and the surface bearing them is said to be pubescent.

The trichomes on Cannabis plants are glandular, which means they produce a secretion. This is similar to the essential oils produced by members of the mint family (Lamiaceae). Plants benefit from the presence of trichomes as they tend to deter predation by herbivores, protect the plants from extreme sunlight and reduce transpiration in dry climates. A favorite tea ingredient of mine, stinging nettle, requires that I cook the leaves to neutralize their trichomes, which are responsible for the stinging aspect.