Basic nomenclature of cannabis genetics

What are IBL, S1, BX, F2 or landrace cannabis plants?

Hindu Kush by Sensi Seeds
Hindu Kush by Sensi Seeds

Often, when it’s time to buy cannabis seeds, the beginner grower can quickly become confused by some of the acronyms that are written next to the name of the variety. Simply by learning some basic concepts you'll be able to make the correct choice between seeds with the same name, but different acronym.

There is a big difference between acquiring a second filial generation (F2) or an IBL, even if we talk about seeds of the same variety. These differences will condition the growth pattern of the plants, and also the final product, so that it is almost essential to learn exactly what is the meaning of these acronyms to be more accurate in choosing which seeds to buy, saving ourselves deceptions and getting closer to our preferences.

Pure varieties

Also known as landraces or purebreds, pure cannabis varieties have been the basis of cannabis breeding over the past decades. These species are endemic to a geographical area, where they have developed without having been crossed (hybridised) with other varieties. There are a large number of landraces from all around the planet, belonging to any of the three families of cannabis, C. sativa, C. indica and C. afghanica. Nepal is a good example; in this country different pure cannabis varieties (mostly narrow-leaved mixed use varieties) are grown and you can easily see the differences between genotypes based on the height above sea level at which they are cultivated.

Each variety expresses its genetic code (genotype) with a certain growth and flowering pattern (phenotype), so that pure varieties - with a purest genotype - show great uniformity, with just a few slight differences between phenotypes. We can expect very little variation between landrace specimens of the same variety, giving plants with very similar growth, organoleptic and psychoactive traits. Good examples of these varieties can be Hindu Kush (Sensi Seeds), Colombia Punto Rojo (Cannabiogen) or China Yunnan (Ace Seeds).

IBL or stabilized cannabis hybrids

F1 Hybrid
F1 Hybrid

The IBL acronym (in-bred line), means that the cross was made using plants with almost identical genotype (inbreeding). On the contray, outbreeding is employed to introduce new genes into the variety. Although it happens naturally, self-pollination is a common technique used by breeders to fix desirable traits and thus stabilise the genetic line, either with landraces or hybrids. In cannabis genetics IBL seeds should present a highly uniform growth. Classic IBL examples are Skunk and Northern Lights (Sensi Seeds) or White Widow (Greenhouse). There is a lot of work behind IBL's like these, as a large population of pure specimens had to be used to select the correct parents. In addition, the breeder must fight against inbreeding depression, the result of crossing parents with very similar genetic information. The reward for this job made properly is a highly stable seed variety.

If we make a cross between two different landrace or IBL lines (parental A and B) with different genotypes, the resulting offspring will be the F1 hybrid, the first filial generation from the cross of the phenotype #1 (Parent A) with the phenotype #2 (Parent B). Commonly in this kind of crosses we will observe a very uniform offspring, depending on how stable the parents are, of course. The F1 hybrid between two pure varieties or IBL's will show the so-called hybrid vigour - also known as heterosis or outbreeding enhancement - introducing new genes that will produce “better" specimens.

Varieties like Orient Express (Ace Seeds), Red Afro (Tropical Seeds) or Eddy from Original Delicatessen would be good examples of true F1 hybrid. Thus, we refer to the first filial generation of any cross as an F1, while the term "F1 hybrid" is used when the parents are different landrace or IBLs.

How to create a polyhybrid
How to create a polyhybrid

When we cross two F1 individuals (whether landraces, hybrid or polyhybrid varieties), we obtain the second filial generation or F2, and so on with next generations, F3, F4, etc. The second filial generation often gives a more heterogeneous offspring than the F1; we can expect 25% to resemble parent A, 25% to resemble parent B and 50% will be a mixed expression of traits from both parents. As a  consequence the stabilisation work must continue generation after generation ( F3, F4, F5…) until we find the generation that gives a uniform offspring with the traits that we are seeking.

Many of the seeds that we can find in shops are polyhybrids, crosses between different hybrids. The offspring of such crosses are in many cases quite unstable, producing plants with very different traits. Keep in mind that in these cases, the genetic mix is very varied, so we can not expect polyhybrid offspring to be as homogenous as an F1 hybrid. It's easy to imagine how complex it can be to stabilise a cross, since we are mixing different genes from different varieties, which makes the selection and stabilisation process of the different traits a very hard work. The vast majority of hybrids on the market are in fact polyhybrids, like the White Russian (Serious Seeds) or Fruity Jack / Jack el Frutero (Philosopher Seeds).

BX or Backcross

Backcrossing is a common technique used by breeders to fix certain traits. This is done by crossing one of the progeny (F1, F2…) with one of the original parents (recurrent parent) which has the desired trait. To have an even more stable expression of the desirable trait, you can cross the BX1 again with the recurrent parent to have a BX2 (squaring) and so on with BX3 (cubing), BX4, BX5...

Backcrossing
Backcrossing

This technique is also used to replicate clones in seed form. It is done by choosing a male parent to cross with the clone only, backcrossing it as many times as needed to get an offspring as similar as possible to the original clone. The Apollo 13Bx (TGA Subcool) is an excellent example of this technique.

Tropimango by Philosopher Seeds
Tropimango by Philosopher Seeds

S1, feminised cannabis seeds

The acronym S1 refers to the first filial generation produced as a result of crossing the plant with itself. This is achieved by a range of techniques aimed at reversing the sex of the selected female plant, getting it to produce male pollen and using it to pollinate itself. If it’s done properly, we get feminised offspring with the same genotype of the parent used.

As always in genetics, the more stable the parent is, the more stable the offspring will be. This technique can also be used as a regular backcross, selecting and fixing traits but starting with just one parent. Thus, we can find S2 or S3 seeds, which have been backcrossed again with the original parent. Examples of S1 are Tropimango (Philosopher Seeds), S.A.D. (Sweet Seeds) or Trainweck (Greenhouse).

Comments in “Basic nomenclature of cannabis genetics” (20)

GreasyTroll
20-05-2020
Hey there great article! I have a question from my most recent Grow. I had a female God Bud and a female Amnesia (descendent from God Bud). The Amnesia hermied on me pretty late on and I could only spot 3 pollen sacs. They open and pollinated both itself and the female god Bud. This resulting in seeds in both plants. Are these seeds going to be feminized because they came from a hermie? Do I have 2 strains happening here? I’m interesting to see and will be germinating seeds from both batches in the future. Just curious. Thanks!
Tim Alchimia
20-05-2020
Hi, thanks for your comment and question. In short, yes the seeds will be feminised, or at least 99.9% certain to produce female plants. You'll have produced an Amnesia S1 and God Bud x Amnesia. However, I would strongly advise against germinating them and growing them. This is because they are the product of a hermaphrodite pant and will, therefore, carry this hermaphroditic trait on to its offspring, meaning you'll be much more likely to have the same problem with future crops, resulting in your buds being seeded again, which I'm guessing is not what you're looking for! I understand that you'd like to salvage something from your seeded crop by planting the seeds, but you will most likely only be causing more problems for yourself in the future. The difference between feminised seeds and hermaphrodite seeds is that to properly make fem seeds, a breeder must first select plants that have minimal (or none at all) hermaphrodite characteristics, this is done by stress-testing the female plants and rejecting any that show male flowers. Then, one of these "sexually stable" plants is treated with a chemical that effectively works to suppress the female flowering hormone and leads it to make male flowers, which produce feminised pollen. Reputable breeders and seedbanks will go to great lengths to avoid using unstable parents in their hybrids, mainly because of the flood of complaints and returns that they would no doubt experience from customers unhappy about all their ruined crops! By all means, feel free to germinate and test these seeds and please let us know how you get on. However, I fear that you may end up regretting it when your next crop is also seeded, effectively negating any saving you may have made by using homemade seeds. Good reliable seeds from a reputable breeder are some of the most important investments a grower can make! Whatever you choose to do, best of luck and happy growing!
Klean
14-05-2020
How are 3 way crosses made? I see lots of strain crosses that will show A x B x C but which is the male and female in this case? Are the B and C strain just the cross on the male? Or are the A and B strains the cross on the female? Or maybe B was the first male used then those seeds were hit with C pollen in a second cycle?
Tim Alchimia
15-05-2020
Hi Klean, thanks for your question. You're correct, it can definitely be a little confusing to work out the genetics in these cases. If a seed bank displays the lineage as simply A x B X C then there's really no way to know how the cross was made. The proper way of writing it is as so: (A x B) x C in which case the female is A x B and the male would be C. Alternatively, A x (B x C) would indicate that the female was A and the male was B x C. Without the brackets it's anyone's guess! Incidentally, the female (or seed-bearing plant in the case of feminised crosses) is always listed first, with the male last. Having said that I have seen breeders list things the wrong way round and state that it isn't important. Personally I wouldn't buy seeds from anyone who can't get something so basic correct! Hope that clears up any doubts. Best wishes and happy growing!
Tobs
02-05-2020
Hi, i have a plant grown from F1 seed i would like to self (s1) as i like the some phenotype i would like to preserve. Will the S1 be identical to the mother or will the seeds still come with some degree of genetic. variability. thanks
Tim Alchimia
04-05-2020
Hi Tobs, thanks for your comment and question. In this case, the S1 offspring won't be identical to the mother plant. Look at selfing like you're basically taking all the genetic information contained in that one plant and "rolling the dice" again, in other words, recombining the same genetics. The results will depend on the genetic stability of the mother, so a poly-hybrid (like most of the modern varieties out there these days) will produce a great deal of variation, a true F1 hybrid (made bt crossing 2 stable, inbred genetic lines) will give some variation while a well-made IBL (In-Bred Line) plant will reproduce fairly faithfully as an S1. If I was to set about trying to reproduce a plant in seed form, I'd probably make S1 seeds then grow out a good quantity of them to select the plants that most resemble the mother. Then I'd probably try either reversing and back-crossing one of these offspring to the mother again, or I'd take the two offspring that most resemble the mother and cross them together. I think that could be a good way to fix the traits you're looking for. I hope that's useful, best wishes and happy breeding!
Pugun
11-04-2020
Hi alchimia, How can i know about Genealogy If (A)x(B) which of (A)×(B) is male or female and Important or not , It's has a rule of this if I need to explain my strain.
Tim Alchimia
11-04-2020
Hi Pugun, as a general rule, the female seed-bearing plant goes first in the description of the cross, so if, for example, you pollinated an OG Kush female with Skunk #1 male pollen, the cross would read OG Kush x Skunk #1, and likewise if you were to pollinate the OG Kush female with pollen from say a reversed Forum Cookies female, then the cross for the feminised seeds produced as a result would be OG Kush x Forum Cookies. I hope that helps clear up any confusion. Best wishes and happy growing!
Thomas Smith
21-11-2019
I bought regular Skunk#1 seeds from Sensi Seeds and wanted to pollinate a female with male pollen in order to build my own supply of seeds. Is there any negative aspects of doing this?
Tim Alchimia
22-11-2019
Hi Thomas, thanks for your question. There's no negative aspect to making your own seeds, although selecting the parent plants which you will use to make the seeds is an important step in the process. Choose one, two or more females that have the characteristics you're looking for, and then pick a male or two that match them. Of course, you can make seeds with just one of each parent, but there's always the risk of creating a "genetic bottleneck" when working with a limited number of plants. This can lead to inbreeding depression, where detrimental recessive genes are allowed to proliferate. When working to reproduce a line such as Skunk, I would recommend using as many parent plants as possible, but being sure to reject any weak or mutated plants. I hope that helps, all the best and happy breeding!
bettyloo
12-09-2019
HI TIm, Thanks so much for this very detailed article. Ive been crossing my tomatoes for practice, looking for the perfect canning tomato. lol ALSO, Ive been working on 2 strains for 2 years now. I call it Biker weed meets Hippy weed. Both were strains from back in the old days that got self pollinated, so to try and save those 2 strains, I crossed each with SSH, taking those crosses and back crossing with themselves as to not intodce any more genes, and try and stablize the strains. Reasons for that, HI tch, HI end of cbd levels, with sativa sweet taste, lots of sweet terpenes for pain, and Shorter budding time. SSh is stated to be difficult, but with the biker or hippy weed mixed in, it buds out quicker. (they both had some afghani and kush in them) Also in doing this, helps to climatize it to our short season for next year. ANyway, I didnt know about labeling s.1, s2....I guess Im at s2 (or 3) this year if I ever want to register this strain. it was very popular among friends, flew out the door faster than any other strain Ive grown (20yrs now). So smooth, great terpine profile for pain, and easy on the lungs. the smell is like heaven, I love pruing those plants, I could live inside there. Anyway, Im happy to know Im doing things the right way from past limited agricultral experience. Your article was Very well explained. Similar to what Im doing with the tomatoes, only a little easier to seperate male from the females and collecting pollen is much easier for sure. Thanks again for this info. Much better than depending on "bro science" like some seed mills. Thanks for the links to those also. Nice to know who is legit.
Tim Alchimia
17-09-2019
Hi bettyloo, thanks for your comment, I'm happy to hear you're making your own cannabis and tomato crosses and that the article was useful. I'm a big fan of SSH myself, it was one of the first clones I grew around ten years ago. Definitely a good variety to work with, it's sure to improve most anything it touches! As for the labelling, if I understand it correctly, you have clones of 2 old varieties and you've crossed them both with SSH, and then crossed the offspring of each cross back to the clones? If you're working with non-feminised ie regular genetics, with males and females, and pollinating the original clone with each successive generation, then what you're doing is backcrossing, and once you made the initial outcross (with SSH) the generations would be Bx1, Bx2, Bx3 etc. S1, S2, S3 etc would be if these were feminised backcrosses, where the plant was reversed and the pollen used to pollinate another clone of the same plant. S2 would be a case of reversing a selection of the S1s to the original clone, or vice-versa. I hope that answers your doubts, if not, please let me know! I wish you all the best, and continued success with your hybrids, happy growing!
Blake
06-09-2019
Judging from the dates on some of the other comments, this is an older article, but this is my first exposure to the Alchimia brand, much less the blog, and I just wanted to thank you for providing this information in a concise, effective, and easily-digestible manner. Especially considering, according to the author, it was translated from Spanish. Very informative for someone like me, who loves cannabis (and even works in the legal cannabis industry in the USA, PNW area) but doesn't know much about actually growing the stuff. Not my department, but I'm slowly learning. This page is getting bookmarked, and I will be exploring more articles!
Keith H
27-06-2019
Hello Tim i love the post but there are a few questions i did not see answered in the post. Lets say i have a f1 hybrid or any strain for that matter and i want to stabilize it. I have picked out a nice mother plant with traits i want what criteria do i use to for the male plant? all the one i have ever grown are tall and lanky . How would i know what kind of traits the male plant would produce before I pollinate it to a female?
Tim Alchimia
28-06-2019
Hi Keith, thanks for leaving your comment and question. Yes, males will usually tend to be more tall and lanky than female plants, I'd imagine that this is a trait that evolved to allow them to stand over the females and spread their pollen further than if they were the same size as them. As for selecting a male, it's not an easy process. You can start choosing plants based on visual and olfactory traits such as structure, colour, leaf shape and aroma when rubbing the stem, selecting the individuals with traits that match the mother plant you want to stabilise. Unfortunately, though, there's no short cut when it comes to knowing what traits the male will pass on to the offspring. The only way to be sure is to make seeds and test the progeny, which is a long and potentially costly process. Another option would be to make a backcross of your mother plant. This involves making an initial outcross with a different male and then pollinating the mother with the males from this first outcross, creating the BX1 generation (backcross). Maes from this BX1 generation could then be used to pollinate the mother again, creating the BX2 generation, and so on, in a process known as "cubing". I hope that's answered your doubts, if not please let us know. All the best and happy breeding!
Aaron
04-06-2019
Hi Tim, Is it still labeled a F1 if a female was open pollinated outdoors and the male is unknown? Or, would it be considered an heirloom? I'm just trying to correctly label my seeds and keep track of the generations. Thanks!
Tim Alchimia
04-06-2019
Hi Aaron, thanks for your question. Strictly speaking, a true F1 would be a cross between two unrelated, stabilised (inbred) lines, however, these days the cannabis world uses the term for any cross between two different plants. In this case, I'd probably label the cross F1 OP (for open pollination) just for clarity. Hope that helps, all the best and happy growing!
MichiGreen
27-01-2019
Many breeders today are crossing 2 strains of cannabis to create a new strain that they sell. From reading this article it appears that they are probably both hybrid parents and not likely to create a true F1 strain that would show hybrid vigor and the best traits of both parents. More likely, the seeds produced would show a wide variety of genetic traits (unstable) and be unsuitable for breeding unless a large number are grown and the succeeding generation parents carefully selected. Am I correct in this line of thinking? Or are these multitudes of "breeders" actually producing seeds that will show stability and expected qualities?
Tim Alchimia
30-01-2019
Hi MichiGreen, thanks for your comment. In short, yes you're correct. The vast majority of seeds available these days are poly-hybrids, or poly-hybrids of poly-hybrids! Cannabis trends/fashions and the speed they move mean that very few seed banks are willing to put in the work required to properly "stabilise" a strain before releasing it, preferring instead to simply cross one hype clone with another and release the results. For the most part it seems to matter little, as many growers these days are happy to "pheno-hunt" for a spectacular example, different to anything anyone else has, that they can clone for future crops, rather than expecting to sow 10 seeds and end up with ten almost identical, "stable" plants. However, with the advent of legalisation in different countries around the world, it's more likely that good, conscientious breeders will be able to make careful selections from large populations of plants to breed with. Hopefully we'll see some progress in that direction and get some stable seed lines. All the best, happy growing!
C. Doyle
06-01-2019
It's elementary Watson
S Holmes
30-12-2018
D Watson. Your self-assured-ness is worrying. Perhaps Afghanistan has had a deeper impact on you than I first thought.
D Watson
04-08-2018
BTW there are no Homogenous varieties being sold, all cannabis is Hetrogenous, and as Cannabis is a dioecious obligate outcrosser that will not change soon.
Tim Alchimia
08-08-2018
Hi again Sam, and thanks for the comment. OK, so if I understand this correctly, we should be talking about uniformity in cannabis plants rather than using the term "homogeneity"? I get that in genetic terms there's a difference, and that cannabis isn't homozygous, it's heterozygous, but can we not describe plants as homogeneous in appearance and behaviour? Personally, I'd argue that homozygous and homogeneous aren't the same, they mean two different things, with homozygous referring to a gene having two matching alleles, while homogeneous, which as far as I know is not a term with a genetic basis, refers to uniformity. I think it's probably fair to describe as homogeneous a seed variety that consistently produces plants with an almost identical appearance, behaviour, terpene profile and effect, even if it isn't homozygous, genetically speaking. Is this wrong? All the best and thanks again for your contribution.
D Watson
04-08-2018
You say STRAIN in this article but that is not a correct term for Cannabis which has seed Varieties or clone Cultivars, you also say Cannabis Indica, Sativa and Ruderalis but the proper taxonomic terms are WLD wide leaf drug, NLD Narrow leaf drug, both are Cannabis Indica, all hemp is Cannabis Sativa, no one is sure about Ruderalis if it a third variety or is just escaped cultivated varieties. Before you attempt to teach you should learn the real terms to use.
Tim Alchimia
08-08-2018
Hi Sam, thanks very much for your input, it's really very much appreciated. I'm going to edit the post to replace the term "strain", that's a good point, thanks for pointing it out. This article was originally written in Spanish and later translated to English, so that may explain it to a certain extent. Believe it or not, we're fully aware of the terms proposed by Karl Hillig, (just to confirm, should it be BLD Broad Leaf drug or WLD Wide Leaf Drug? I've seen both used) and while we do sometimes use these terms where appropriate (and we'd like to use them more), we're not writing scientific studies here, we're just trying to inform and help out your average home-grower. I agree, it's important to be educated in order to educate others, but I also think a balance needs to be struck between strict scientific accuracy on one hand, and accessibility of information on the other, we need to present things in way that can be easily understood, without requiring too much additional explanation: everyone knows what we're talking about when we say "Sativa, Indica or Ruderalis", and as I'm sure you're aware, most growers couldn't give two hoots about using the proper botanical terms, indeed some are proud of not using them! It's an interesting subject, and one that we'll probably address in another post fairly soon. I'm all for teaching our readers the correct terms to use when talking about cannabis, but whether they actually use it or not is another matter. Like they say, you can lead a horse to water... Thanks again for taking the time to comment, all the best!
Nicolas
22-06-2018
Hey Tim, then how would you call a "F1" cross between two diferent Hybrids?
Dani Alchimia
25-06-2018
Hi Nicolas, Tim is on holidays, so I'll reply your comment. Well, since "F1" theoretically means "first filial generation", I often call my crosses "F1" no matter if they come from a single landrace, from two different landraces or from hybrids. Some people will tell you that it only stands for a cross between two different landraces, although most breeders call the first filial generation "F1" regardless the genetics/parents used to develop it. Hope it helped!
xyz
07-06-2018
not sure if i understand the question correctly..but there is much more than just crossing..main work is selection .
Mike H
23-04-2018
Hi, Tim- How would an enthusiast breeder fix the genotype to produce both a homozygous male and female before crossing? As you know cannabis is dioecious. The goal is to produce uniformity in the F1 generation. Is backcrossing the best way to go? I can't seem to understand how backcrossing would be able to introduce desirable traits from the female if the donor is the male. Great article!
Ripper
17-03-2018
No tim an f1 is a cross between two different cannabis strains.
Tim Alchimia
29-03-2018
Hi Ripper, thanks for your comment. That's pretty much what I was saying, a true F1 is a cross between two genetically distinct but true-breeding pure lines. My point is that you can't cross two modern poly-hybrid strains together and call the progeny a true F1. All the best.
Dennis
13-12-2017
How do we find F1 seeds, can we trust the seed company? As I have never seen a seed company that says F1 seed, just the names that they Sell.
Tim Alchimia
15-12-2017
Hi Dennis, thans for your question, you're right, it's not common to see that kind of information on cannabis seed packs or catalogues. This is probably because most cannabis breeding isn't carried out by qualified geneticists specialising in botany, but by enthusiasts and veteran growers, meaning that much of the terminology employed by professional geneticists is either misused or not understood in the cannabis seed indusrty. A true F1 hybrid should be a cross using two different, pure varieties, however much of what cannabis breeders refer to as "F1" are crosses between hybrids or polyhybrids and so are not strictly "true F1" hybrids. If you're looking for good F1 hybrids from reliable and trustworthy breeders, from my own personal experience I can recommend three Spanish seed banks: ACE Seeds, Cannabiogen and Tropical Seeds, and also a great French seed bank Underground Seed Collective, all of whom do some great work with pure landrace genetics, producing some spectacular F1 hybrid seeds. I hope that helps, all the best!
Daniel S Lennox
13-10-2017
Hi All, I just want to ask if anyone ever tried using medical cannabis as an alternative meds? I have read many articles about medical marijuana and how it can help you in terms of chronic pain, bone injuries, eating disorder/anorexia, anxiety disorders and panic attacks, inflammation, even cancer and a lot more. Cbd and thc are also new to me and I don't even smoke. If this is true I cant find any solid conclusive evidence that speaks to its efficacy. Any personal experience or testimonial would be highly appreciated. Thanks
Tim Alchimia
15-12-2017
Hi Daniel, thanks for your question, sorry for taking so long to answer, I'm afraid it must have slipped through the net! In answer to your doubts, yes! Many people worldwide have experienced huge success using cannabis as an alternative to pharmaceutical treatments. There is an ever-expanding library of online articles and studies into this subject and as the legal situation improves in the USA we can expect to see even more scientific evidence as to its efficacy. Have a look at the section of our blog that deals with Medical Cannabis and if you have any more questions then leave a comment for us on the appropriate post. All the best!

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