David C. Zlesak, University of Minnesota Extension Educator
Martagon, Asiatic, Oriental, trumpet, and tiger lilies (blooming approximately in this order from late spring through summer) are groups of amazing lilies that have beautifully graced our Minnesota gardens for decades. The martagon lilies have beautiful whorled foliage, flower early with wonderful clusters of typically downward facing flowers with recurved petals, and are even relatively shade tolerant. The Asiatic lilies are probably the easiest for us to grow here in Minnesota. In amenable sites they typically multiply well and provide a glorious show of blooms in probably the widest color range possible of all the different commercial lily classes. The Oriental and trumpet lilies have large, intoxicatingly fragrant flowers. The fragrance is especially powerful in the evening and throughout the night. I love coming home at night and being taken back by the rich, wafting fragrance of my Lilium regale lilies (a white trumpet lily) and ‘Casa Blanca’ Oriental lilies as I walk to the front door. Tiger lilies have magnificently speckled orange or yellow blooms typically with recurved petals similar to the martagon lilies.
We can routinely find cultivars of these traditional lily groups in our favorite catalogs and garden centers. However, in recent years there has been amazing advancements in very wide crosses between lily classes that previously were not able to produce successful offspring. Crosses between different classes have led to the development of new lily classes with many of the positive features of their parents. Special pollination techniques and techniques using tissue culture to “rescue” embryos have made it possible to recover hybrids from these wide crosses. These wide crosses are often called intersectional crosses because they are crosses made between different sections of the genus.
Botanically under the level of genus (Lilium is the genus of true lilies) there is the taxonomic level of section. Lily species that are within the same section are more similar genetically than lily species in different sections and tend to cross more easily among themselves (typically without the aid of tissue culture). For instance, crosses of multiple lily species in the section Sinomartagon led to the modern Asiatic lily cultivars we enjoy. Without tissue culture, sometimes intersectional hybrid embryos form, but the nutritive tissue (endosperm) around the embryo fails within a couple to few weeks after pollination and then it dies. If the embryo can be removed from the mother plant before it dies and placed in tissue culture where it can receive the nutrition it needs and continue growing. There are several modifications that can be made to the process in order to find ways that will work to recover different wide crosses.
These are some of the most popular intersectional lily classes on the market.
LA refers to Longiflorum and Asiatic. These lilies are crosses between Easter lily (Lilium longiflorum) and Asiatic hybrids. They first came on the market in the early 1990’s. They look a lot like Asiatic lilies (flowers tend to be flat like Asiatics), but tend to have larger flowers with thicker petals than the Easter lily parent. Early LA hybrids tended to have colors within the pastel shades. Breeders have been able to backcross early LA hybrids to Asiatic lilies to intensify color and strengthen hardiness and other traits. Interestingly, breeders have not reported successful backcross hybrids to Easter lily parents. Modern LA hybrids tend to be as durable in Minnesota as Asiatic lilies. They are used widely in the cut flower industry and tend to be relatively easy to force in pots like Easter lilies.
Orienpets are crosses between Oriental and trumpet lilies. They tend to have huge, wonderfully fragrant flowers in a very wide array of colors and color combinations. The flowers generally tend to be more open faced like the Oriental parent. In Minnesota Orienpets tend to be more adaptable and durable than Oriental lilies. Plants typically are quite large. Many common Orienpet hybrids routinely grow to about 6’ tall and benefit from staking. The North American Lily Society has a yearly popularity poll. Those that win over multiple years are eligible to eventually be elevated into the lily Hall of Fame. Two very popular Hall of Fame lilies are of the Orienpet class and are ‘Silk Road’ and ‘Scheherazade’.
‘Silk Road’ is a lovely red / white bicolor and ‘Scheherazade’ is beautiful red / yellow bicolor.
LO hybrids are crosses of Easter lily and Oriental lilies. They have just come into the marketplace the past few years. The most common cultivar gardeners are likely to find is ‘Triumphator’. In many ways it looks like an Easter lily with its beautiful, elongated trumpet, but the throat of the bloom is a gorgeous, rich red. It will be exciting to see more LO cultivars come on the market in the near future. Early reports are favorable for ‘Triumphator’ being able to overwinter in Minnesota. More time is needed to be confident how well cutivars of this new class will routinely perform in Minnesota.
Progress is being made on additional intersectional classes. For instance, there are beautiful hybrids in existence between martagon and Asiatic lilies. Hopefully soon they will become widely available. Recent intersectional lily hybrids offer even more great lily options for the Minnesota gardener.
The North American Lily Society (NALS) is a great resource to learn more about lilies. There are also local chapters. In addition, NALS has a nice seed exchange they host each year where members can obtain seeds of amazing lily species and also seeds of crosses and open pollination of lilies in almost every major class.