I wanted to start a thread on hybridizing goals but thought it might be good to do a lead-in thread first on species & hybrid classification so the terms used are clear.
Species:
For this thread we are focusing on the genus Lilium and the species classified under this genus. There are a few genera closely affiliated with Lilium (Nomocharis, Notholirion, & Cardiocrinum) in the Liliaceae family that have been grouped with Lilium by different authors at different times but are excluded from my comments here. There are around 100 to 120 different Lilium species currently recognized and they are found primarily in the Northern Hemisphere. The definition of species can be very complicated and there are several schools of thought with respect to defining species (“Lumpers” tend to lump or group things into fewer broader species & “Splitters” tend to look at smaller variations and consider that as criteria to split things into smaller groups = more species). The definition I prefer to use for species is “a wild population of plants that resemble one another in certain key characteristics and can reproduce by seed resulting in seedlings that fall within the normal variation of the wild population and are stable over several generations.” If two wild populations can’t produce seed when crossed that would be a key indicator they are different species. There are a few naturally occurring hybrids but very few are reported in Lilium.
H. F. Comber published in the Royal Horticultural Society “The Lily Yearbook 1949” a proposed grouping of individual species into 7 different sections based on a number of criteria. Those criteria were - Germination (IE-IH-DE-DH), Leaf arrangement (whorled-scattered), Bulb scale (jointed-entire), Seeds (heavy-light), Bulb shape and habit (erect - sub-rhizomatous – rhizomatous – stoloniferous), Perianth segments (papillose-smooth), Nectary (pubescent-glabrous) , Flower shape (turk's cap-trumpet), Bulb color (white-purple), Stem habit (erect- stoloniform), Petiole (obvious - obscure or absent), Stigma (large-small), Stem roots (present-absent), Stems per bulb (one-sometimes two). This grouping was an improvement over the previous attempts to group all the lily species based on flower form alone.
Species Sections from Comber 1949
1) Martagon (Martagon)
2) American (Pseudolirium)
3) Candidum (Liriotypus)
4) Oriental (Archelirion)
5) Asiatic (Sinomartagon)
6) Trumpet (Leucolirion)
7) Dauricum (Daurolirion)
One of the best resources I have found on the internet for Lilium species is the link below & the information on this web site is pretty much what you read in most lily books that discuss the species and their organization into groups:
http://www.the-genus-lilium.co...
Since Comber’s publication and adoption of the grouping of species by section, there has been a great deal of new information. This new information comes in the form of additional data on which species can readily be crosses with one another and the most recent advances have been with genetic/DNA analysis. Based on some of this more recent data, there is certain to be some proposed changes in the groupings of Lilium species – one such proposal is shown here:
http://www.the-genus-lilium.co...
Regardless of how you group the species, it is wise to consider each one with its own special requirements as many have adapted to very specific microclimates and require special growing conditions. Some species can be very adaptable and long lived while others require exacting growing conditions to survive and even then require regular replenishment by growing new from seed. It is important to understand the soil, moisture, temperature, light, and nutrient requirements for the species you are considering growing as these can make or break your attempts with a certain species. If you can find someone growing the species you are interested in, it is great to ask them how they grow it and what their recommendations are.
For me, the species that is my white whale, great white buffalo, unicorn, or Holy Grail is Lilium speciosum var. gloriosoides from China. I have grown it for a very short time (familiar story for those who have tried) from wild collected bulbs and trying again now to grow it from seed. In this particular species, I have not found someone able to grow it for more than a few years without losing it – the closest I have heard of success was from Rod Barwick in Tasmania. In this case I believe the biggest challenge for us to learn how to grow it is the fact that it is listed as a subspecies of L. speciosum from Japan and we assume it requires similar growing conditions. In my opinion, the L. speciosum var. gloriosoides from China is a fully separate species from those in Japan and also a separate species from the form found in Taiwan. The reason I believe this is because 1) these forms do not make seed when crossed to each other, 2) they are in separate locations separated by sea, & 3) they have a physical differences in flower color/pattern & flower shape (haven’t seen them side by side to compare other attributes). I recently found there to be a large number of pictures that people have posted on Facebook of the Taiwan form and a few pictures of the China form which has further convinced me these are all separate species. I look forward to someone doing a formal evaluation of these species and would love to hear from anyone having success in growing the China form as there is very little information available on the growing conditions in the wild for the China form.
Hybrids:
A hybrid is a seedling resulting from the cross of two different species, a hybrid & a species or two hybrids. Crossing two different populations (collection locations) of the same species would not normally be considered a hybrid unless the different populations are considered subspecies. Just as the species were divided into groups and assigned a section, hybrids are classified into divisions. The confusing part for me is that the species sections and hybrid divisions don’t line up. For instance, the Asiatic or Sinomartagon (Section 5) & Dauricum or Daurolirion (Section 7) species fall under the Asiatic hybrids in Division I and the Trumpet or Leucolirion (section 6) species hybrids are split into the Longiflorum Division V & Chinese Trumpet Division VI groups. The only section/division that sort of lines up is for Candidum where Section 3 goes in the Division III. I am not proposing a change here just pointing out the fact that they are different (which can be confusing) and could benefit from an overhaul based on the knowledge we have today. Each division is composed of hybrids from a defined group of species that for the most part intercross readily. There are different hybrid sub-groups within a division based on their ability to intercross – for instance in the American hybrid section, the Western American species intercross and the Eastern American species intercross but crossing Western & Eastern species has been very difficult and only been documented in a few cases. Just because a species is affiliated with other species by being grouped into the same section does not mean it will easily produce seed when crossed with other species of the same species section. It has been very difficult to get some species to hybridize with any other species or hybrid regardless of the section it is grouped into. Here is the hybrid Division groups:
Hybrid Classification Divisions
I) Asiatic
II) Martagon
III) Candidum
IV) American
V) Longiflorum
VI) Chinese Trumpet
VII) Oriental
VIII) Interdivisional Hybrids including LA’s, OT’s, OA’s, & LO’s.
And here is a drawing I made to try to represent the relationship of the species sections to the hybrid divisions:
There are different preferences when it comes to species and hybrids. Some folks only grow species and have absolutely no interest in hybrids while others grow only hybrids but most people fall somewhere in the middle and choose to grow a mix of both. The beauty of the species is undeniable as is the challenge to grow some of them in each of our unique climates that often don’t match up well with some of the species native habitat. In general hybrids can be easier to grow. There are several advantages hybrids can have over species including hybrid vigor & greater adaptability to a wider range of growing conditions. Through hybridization new attributes not found in species can be achieved including new flower shapes/sizes, new flower colors & patterns, larger and smaller plant size, and greater durability. A hybrid combines the attributes of both parent plants into a new plant and each parent plant often has strengths and weaknesses. The hope of hybridizers is to maximize the best qualities of both parents and minimize the undesirable qualities. For instance, a hybridizer could choose to cross a pink flowered lily with a weak stem with an orange flowered lily with a strong stem in hopes of getting a pink flowered lily with a strong stem. The challenge is that you may also end up with an orange flowered lily with a weak stem. My point in mentioning this here is to ensure it is clear that just because a plant is a hybrid does not ensure it is a better plant.
There are some additional terms used in hybrids that would be useful to introduce here. When two lilies are crossed that are not of the same species or of the same genetic background, the first generation cross is referred to as the F1 generation. If siblings from the F1 generation are crossed the resulting seedlings are referred to as the F2 generation. If F2 siblings are crossed they produce the F3 generation and so on. This can be useful terminology when discussing multigenerational crosses. Another useful term is backcross - this is where an F1 seedling is crossed to one of its parents.
Hopefully this information is helpful as we discuss further topics.
