Bert wrote (regarding hybrid swarms): > How do we designate the > relationship between such > hybrids and the man made one of 50%A and 50%B and express the > fact that they may > have the same parentage but variable contributions from each parent?
Hi Bert, I think the bottom line is that the grex nomenclature system doesn't map onto natural hybrids very well. If I remember correctly, the offspring of a primary hybrid backcrossed to one of the parents have a new grex name, but when two of the same hybrid are intercrossed, the offspring retain the same grex name. If the exact same crosses occur in a natural hybrid swarm, all the plants would bear the hybrid name (e.g. Cattleya guatemalensis) If you want precision, it is probably necessary to specify the cross and give the generation (e.g. F1, F2, F3 for intercrosses and F1, N2, N3 for backcrosses). This data would, of course, be unknown for a natural hybrid swarm. Guido wrote: > I think the problem is much more complex. If you cross species A with species > B you get a hybrid which will be > intermediary, but not necessarily 50/50 ... remember Mendel's laws Actually, Mendel dictates that a first-generation primary hybrid will have exactly 50% contribution from each parent species (ignoring minor contributions from maternally inherited DNA in mitochondria and chloroplasts). It is in later generations of a cross that things become less certain. That's why those charts, so popular in orchid books, that claim a certain hybrid is 25% species X and 12.5% species Y are pretty silly. Of course, that doesn't mean that all siblings of a particular primary hybrid cross will look identical. Variation in the offsping will be dependent on the degree of heterozygosity in the parents, but those offspring will all still be 50% each parent. Nick -- Nicholas Plummer [EMAIL PROTECTED] > > Bert > Pressman > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > /pipermail/orchids_orchidguide.com/attachments/20050627/eeb7398c/atta chment-0001.htm > > ------------------------------ > > Message: 5 > Date: Mon, 27 Jun 2005 10:21:09 -0400 > From: [EMAIL PROTECTED] > Subject: [OGD] Xenia / 1854-1900 > To: [email protected] > Message-ID: <[EMAIL PROTECTED]> > Content-Type: text/plain; charset=us-ascii; format=flowed > > Thanks to Guido for his comments about Xenia which seem to confirm > that the > reference citation in the database 'Index Nominum Genericorum' for > the > first publication of the genus name Aa is accurate : > Xenia Orchid. 1: 18. 1 Apr 1854 > > ********** > From the info provided by Guido about Volume 1 of Xenia > Orchidacea > ["published between 1 April 1854 and 15 October 1858"] > one can deduce that it was published in fascicules. > > It would be interesting to establish : > 1) how many fascicules were published and on what dates ; > 2) how many volumes of Xenia Orchidacea were published between > 1858 and 1900. > > Of course, that is something that someone who has access to Xenia > Orchidacea in its entirety would be able to clarify. > I will try and contact librarians. > > ******* > Regards, > > Viateur > > > > > ------------------------------ > > Message: 6 > Date: Mon, 27 Jun 2005 13:33:54 -0400 > From: Charles Ufford <[EMAIL PROTECTED]> > Subject: [OGD] Re: herbarising > To: <[email protected]> > Message-ID: <[EMAIL PROTECTED]> > Content-Type: text/plain; charset="US-ASCII" > > on 6/27/05 1:18 PM, Guido wrote: > > > Viateur > > > > Why don't you list the story about the Kew people herbarising 17 > of 18 plants > > of Cypripedium calceolus at the only Cypripedium cite in > England! (Well I > > guess you could say that they moved to site to Kew). > > > > regards > > Guido > > > There are some good examples of 'herbarising extinction' in New > York State. > While viewing records of specimens collected for various > herbariums during > the early and mid- 1900's, I became painfully aware that several > species of > terrestrial orchids that had made headway into Central and the general > Upstate NY area from points West, North and South, had been > collected at > several locations year after year until they no longer existed in > thoseareas, extinct in the state or were in extremely small > numbers and usually > only found on Long Island. Everybody wanted to have a specimen, > includinginstitutions not in the state, and the plants just > couldn't reproduce fast > enough. Not that bad nowadays, just the backyard shovellers that > have to be > diverted somehow. > > charles > > plants jumping up and flowering quickly in this heat > -- > Charles Ufford > Oriskany, NY USA > IPA, Central NY and Southern Tier Orchid Societies > Http://www.paphiopedilum.net > Http://www.geocities.com/charlesufford > > > > > ------------------------------ > > Message: 7 > Date: Mon, 27 Jun 2005 20:35:32 EDT > From: [EMAIL PROTECTED] > Subject: [OGD] Re: Orchids Digest, Vol 7, Issue 323, Message 5. > Personal Comment (Dr. Braem) > To: [email protected] > Message-ID: <[EMAIL PROTECTED]> > Content-Type: text/plain; charset="us-ascii" > > > > What is our common goal? Discussions of orchids? > > > Stitzelweller > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > /pipermail/orchids_orchidguide.com/attachments/20050627/5deb8750/atta chment-0001.htm > > ------------------------------ > > _______________________________________________ > the OrchidGuide Digest (OGD) > [email protected] > http://orchidguide.com/mailman/listinfo/orchids_orchidguide.com > > > End of Orchids Digest, Vol 7, Issue 324 > *************************************** > _______________________________________________ the OrchidGuide Digest (OGD) [email protected] http://orchidguide.com/mailman/listinfo/orchids_orchidguide.com
