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Tom Waters

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The Fertile Families of Bearded and Aril Irises


Welcome to Telperion Oasis, Tom Waters's web site devoted to the theory and practice of hybridizing bearded and arillate irises.

Since the middle of the 20th century, iris enthusiasts have been aware of the importance of chromosome configurations in iris breeding. Some configurations have limited fertility, while others constitute "fertile families" that can be developed and refined by multigenerational breeding programs.

This site focuses on the six tetraploid fertile families of bearded and arillate irises:

The 48-chromosome bearded irises, both tall and median (TTTT)

The 44- to 46-chromosome amphidiploid arilbreds, both tall and median (AATT)

The 40-chromosome amphidiploid dwarfs and medians (PPTT)

The 40- to 44-chromosome tetraploid arils (AAAA)

The 32-chromosome dwarf species Iris pumila (PPPP)

The 36- to 38-chromosome amphidiploid aril/pumila hybrids or "arilpums" (AAPP)

(For an explanation of the four-letter notation, see Chromosomes: Concepts and Terminology.)

Within each of the groups, the irises are generally fertile with each other, allowing one to breed for generations to select for new and desirable traits. Each one of these families is hence a reservoir of genetic potential for the irises of the future. With many wild irises threatened in their natural habitat or difficult to maintain in gardens, it is important that each of these families include a robust range of genetic material from as many species as possible. Although most hybridizers will continue to work with the newest garden varieties in the hopes of creating improved varieties that will win the appreciation of gardeners and judges, it is also important to ensure the long-term diversity of each family by including some of the plants that are more difficult to obtain or work with.

I hope you enjoy the site and the photos of my rather modest iris collection. Photos of this year's bloom are on the Bloom Season 2017 page. Blooms from previous years (many photos) can be seen by clicking the year-by-year links on the About the Garden page.

I've donated many seeds of Iris pumila as well as some Iris attica to the 2014 and 2015 SIGNA seed exchanges. The 2014 donations were all hand pollinated. Refer to this page for an illustrated description of each cross.

Tom Waters

September 2010

updated November 2017

Unless otherwise noted, all text and illustrations copyright Tom Waters and all photographs copyright Tom or Karen Waters. Please do not reproduce without permission.