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Hi Nadine!

Nadine Vreeland


Propagation of Native American  Cypripediums

Current Status

by Aaron J. Hicks

Many of our donors request seed of Cypripedium species. If you are  not familiar with the seed propagation of these species, you are strongly  advised to carefully consider the following comments. Cypripediums are  desirable, but propagation of these species via seed is not a trivial matter.  The vast majority of orchids require specialized conditions under which to  germinate if we are to produce an acceptable number of seedlings. Cypripediums  are even more demanding, requiring specialized disinfection techniques, special  media, and sometimes peculiar temperature regimes.

The first thing to consider is whether or not your cultural conditions will  permit cultivation of members of the genus. These temperate terrestrials require  a cold resting period, and are therefore unlikely to survive from year to year  without several months of cold weather. Without refrigeration or (preferably)  naturally cold conditions, they will perish.

The second thing to consider is whether or not you have the correct media  upon which to raise these species. Although some temperate terrestrials  (paphiopedilums, phragmipediums) germinate well on media formulated for tropical  epiphytes, the greatest success with growing cypripediums from seed will be  achieved using media formulated for this genus.

There are several excellent sources for details on these media. Some growers,  such as Bill Steele of Spangle  Creek Labs, utilize a modification of Harvais' (1982) medium. This formula  was written up for the North American Native Terrestrial Orchid Society, as part  of the conference proceedings in 1996. Copies are available for $25 for the  paperback copy from:

North American Native Orchid Conference
14320 Poplar Hill  Road
Germantown, MD 20874

The 1989 NANTOC proceedings are available through the Brandywine Conservancy  bookstore: (610) 388-8326

Also noted in the NANTOC proceedings are the  formulae for media that utilize amino acids for cypripedium propagation, as  written by Svante Malmgren. These media use different nitrogen sources than  "traditional" media that are generally used for epiphyte. Some growers have had  success using commercial amino acid preparations, such as Sigma's RPMI amino  acids; others use health food store amino acid preparations. Bill Steele has had  good results recently using casein hydrolysate at 200 to 400 mg/L, either singly  or in conjunction with ammonium nitrate.

What may be another important factor in germination of cypripedium seed is  whether or not the seed has been refrigerated. For temperate terrestrials, most  species must be refrigerated for at least 3 months prior to attempting to  germinate it. With only a few exceptions, all cypripedium seed shipped from the  OSP has been refrigerated at least that long before we ship it out.

Lastly, cypripedium seed is unusual in that it often contains germination  inhibitors that must be destroyed prior to successfully producing seedlings.  There is some discussion as to whether these are inhibitors being burned up, or  the seed is "wetted" through the aggressive treatments outlined below, and their  importance seems to vary between species. All the same, rigorous bleaching is  required for at least some species of Cypripedium to germinate. For  those species that require it (see Steele's excellent article, as above), the  seed is disinfected as usual- but the time is extended to the point where the  inhibitors are burned up. This can take as little as 30 minutes, or as long as 4  hours. Steele uses a 10% bleach solution, for as little as 20-40 minutes for  species like Cypripedium kentuckiense, to 2-6 hours for Cypripedium  acaule. Again, referring to Steele's article will be most helpful for those  that wish to grow cypripediums from seed.

Scott Durkee, of The  Vermont Ladyslipper Company uses Steele's techniques for propagation of  cypripediums, and expects to have several species for sale later. At this point  in time, he has mature specimens of Cypripedium reginae available as  being propagated from seed. He has also had success in flowering Cypripedium  acaule from seed, which has proven to be a difficult task in the past. His  technique differs from others in that his feed water has been acidified to  between pH 4 and 5 through the addition of cider vinegar. Although there are no  clear reasons as to why this works, Scott believes that the acidic environment  destroys pathogens that have caused failure to thrive or death in other attempts  to grow C. acaule. In conjunction with a watering schedule that tends  to keep the plants dry, Scott has had success in growing and flowering  seed-grown plants of this desirable species.

Although the OSP has offered cypripedium seed for sale almost since its  inception, we find that success is generally low for different reasons. We  provide seed first to conservation efforts, and then to hobbyists and growers,  in an effort to try to land as much seed as we can into the hands of experienced  propagators. It is expected that as word is spread that these species are now  available as live, propagated plants with reasonably high expectations of  survival (something that can not always be said of specimens dug from the wild)  will gain popularity. Soon, it may be possible to have a collection of slipper  orchids in your own garden.

The OSP will continue to provide orchid seed from donors who strive to  provide other growers with legally and ethically harvested seed in an effort to  promote the cultivation of these species "in captivity." Before long, perhaps we  will be able to provide enough plants in cultivation that we can make a serious  dent in "diggers" and other unethical operations. We look forward to progress on  this front.

News update 4/28/00

PhytoTech Labs now  sells Malmgren's medium and Steele's 1996 modification. They are not listed on  their webpage! Malmgren's is listed as M 551, and Steele's variation is T 849.  These media may be used for the germination and culture of cypripedium species;  previously, growers had to formulate their own. Bear in mind that both  Malmgren's and Steele's media have many minor variations in order to produce  optimum results with individual species; growers are encouraged to read more  about these in the NANTOC Proceedings and elsewhere to determine which  variations are best applied to culture the species of interest.


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