When I bought my very first Orienpet lily many years ago, ‘African Lady’, they were still something of a novelty, especially here in Quebec. I remember feeling as though I had discovered something rare and slightly mysterious, a lily with the fragrance and presence of an Oriental, but the strength and stature of a Trumpet. An OT, as it was called. I had no idea that a single purchase would spark a lasting fascination.

Then came ‘Tabledance’. I thought I was adding another OT, but it turned out to be something different entirely: a hybrid between Longiflorum and Oriental, known as an LO. So where does this confusion come from?

Today, my garden holds more than 110 different lily varieties. And the more I collect, the more curious I become. Each new addition sends me searching for answers about its parentage, its flower form, and those intriguing letters and numbers listed in specialist catalogues. Why is one lily placed in Division VII and another in Division VIII? And in Division VIII, aren’t there more hybrids than the Orienpet ones?

The deeper I explore, the more captivating the world of lily classification becomes. What once looked like coded shorthand now feels like a language of its own, one that reveals ancestry and character and even hints at what to expect when the buds finally open.

In this post, I would love to share what I have learned about lily divisions and how to decode the letters you see in registries and catalogues. I’m no expert. But because once I have started to understand that language, collecting lilies has become even more rewarding.

The true lilies : Lilium

Gardeners, breeders, and nurseries organize the diversity of cultivated varieties (cultivar or cv.) into standard horticultural divisions. This system lets gardeners quickly grasp what a lily is like, including its background, flower shape, growth habit, scent and how to grow it successfully.

The nine horticultural divisions

The Royal Horticultural Society (RHS) system, widely accepted internationally, divides Lilium into nine divisions based on parentage and characteristics rather than botanical taxonomy. They are found in the International Lily Register and Checklist (2007 PDF). I have listed them below:

1. Division I – Asiatic Hybrids
   Hybrid lilies derived mainly from Asian species. These are typically sturdy, earlier-blooming, brightly colored, and often unscented.
2. Division II – Martagon Hybrids
   Based on Lilium martagon and relatives — elegant but more woodland-type, often with nodding flowers.
3. Division III – Candidum Hybrids
   Including hybrids related to Lilium candidum, with their own horticultural traits and traditional garden use.
4. Division IV – American Hybrids
   Derived from North American wild species; they often have a different scent and floral structure.
5. Division V – Longiflorum Hybrids
   The classic “Easter” lilies and relatives of Lilium longiflorum — trumpet-shaped, usually white, and highly prized for cut flowers.
6. Division VI – Trumpet & Aurelian Hybrids
   Large, often heavily scented flowers; includes classic trumpet groups.
7. Division VII – Oriental Hybrids
   Known for large, often scented blooms (think Stargazer or Casa Blanca styles), derived from East Asian species.
8. Division VIII – Other / Interdivisional Hybrids
   Hybrids that span divisions (e.g., LA — Longiflorum × Asiatic, OT — Oriental × Trumpet, OA — Oriental × Asiatic, etc.) fall here.
9. Division IX – Species & their Cultivars
   All the wild species and naturally occurring forms (and cultivars selected from species) not placed elsewhere.

ABC to v: Subcodes for flower habit & form

In registries and catalogues, you’ll commonly see letters and numbers following the division. These lilies are further categorized by the way their flowers are presented and shaped. The International Lily Register also introduced this system.

• (a) = up-facing flowers
• (b) = outward-facing flowers
• (c) = downward-facing flowers
• /a, /b, /c, /d = additional codes for flower form (e.g., trumpet, bowl, flat, recurved)

So a cultivar listed as I(b/c) tells you:

• It’s in Division I (Asiatic hybrids)
• It has out-facing (b) flowers
• Its form is between two shapes (flat and/or recurved)

This shorthand gives breeders and growers a quick visual impression of what the plant looks like without a longer description.

Interdivisional hybrids

When you see two letters together, like:

• LA = Longiflorum × Asiatic
• OT = Oriental × Trumpet
• OA = Oriental × Asiatic

These are interdivisional hybrid groups. They indicate a cross between the parent groups involved and are placed under Division VIII in the register.

These combinations are especially popular because they often combine desirable traits (e.g., scent from Orientals with vigor from Trumpets).

A few things to remember

The division system used for lilies does not follow strict botanical phylogeny. In other words, it does not attempt to reflect the exact evolutionary relationships between species. Instead, it is a practical horticultural system developed by breeders and growers. Lilies are grouped by ancestry, flower form, growth habit, and bloom time, helping gardeners and exhibitors know what to expect.

t is also important to note that the registration of lily cultivars is voluntary. The international authority responsible for registering these cultivars is the Royal Horticultural Society. Because registration is not mandatory, some cultivars offered in catalogues or garden centres may not appear in the official register.

Nevertheless, the classification codes used by breeders and nurseries provide valuable insight into a plant’s background and allow gardeners to compare similar lilies more effectively. A wide range of newer hybrids can be found, particularly in Division VIII, as well as among the double Orientals and double Asiatics. Many of these are pollenless and, for now, remain unregistered, though it is hoped they will be included in the future.

In the meantime, I continue to list all my cultivars and diligently verify whether they are registered.

These codes are widely used in flower shows, plant labels, and nursery catalogues. They allow gardeners to quickly understand what to expect from a cultivar: approximate height, bloom season, flower orientation, fragrance, and overall garden performance.

For example:

• Lilium ‘Star Gazer’ (VIIa/c) is an Oriental hybrid with upward-facing, strongly reflexed flowers and a powerful fragrance. It typically blooms in mid to late summer on tall stems. It is often falsely sold in nurseries under the name ‘Stargazer’.
• Lilium regale (IXb/a) is a species of lily. The code indicates trumpet-shaped flowers that face upward, and the plant is famous for its intense fragrance. In my garden, it is definitely the tallest lily to date.
• Lilium ‘Conca d’Or’ PBR (VIIIb/b) is an OT hybrid (Orienpet). The PBR means it is protected under Plant Breeders’ Rights, giving the breeder exclusive rights to propagate. The code indicates it belongs to Division VIII (interdivisional hybrids) and has outward-facing, bowl-shaped flowers, combining the vigour of trumpet lilies with the elegance and fragrance of Oriental lilies.

Learning to recognize these divisions can help gardeners choose lilies that bloom at different times, reach different heights, or provide fragrance in specific areas of the garden, making it easier to design a more interesting and season-long display.