Ploidy and Fertility

J.E. Shields
Wed, 12 Dec 2007 09:55:50 PST
Hi all,

I'm going to take the liberty of cross-posting this to PBS because I 
suspect there may be a couple people in this list who are interested in 
Hippeastrum species and breeding:

Posted to the Hippeastrum Species Group (on Yahoo Groups):

In looking into publications transferring species from Amaryllis to 
Hippeastrum, I have received a copy of one paper of more interest:

Margot Williams & T.R. Dudley, "Chromosome count for Hippeastrum 
iguazuanum" in TAXON, vol. 33: 271-275 (1984)

These workers found that H. iguazuanum has a chromosome number 2N = 24 
whereas the normal diploid number for most Hippeastrum species is usually 
2N = 22. They also comment that H. morelianum has 2N = 24 while H. forgetii 
has 2N = 22 + B.

The B is a small chromosome fragment, and Williams suggested that the 12th 
chromosome pair in iguazuanum and morelianum may have originated with the B 

Crosses of either iguazuanum or morelianum with a diploid (2N=22) species 
would yield offspring that were aneuploid. They confirmed that such a 
hybrid was aneuploid with 2N = 23. I made the cross [iguazuanum X 
leopoldii] (or perhaps someone sent it to me? I can't recall) about 30 
years ago, and found it quite sterile. It resisted all attempts to cross it 
with anything else. See it at:…

We can expect the same with crosses of morelianum, and this latter species 
(unlike iguazuanum) is regularly available as seed from Mauro in Brazil.

Has anyone made crosses with Hippeastrum species and found the offspring to 
be fertile? Please tell us about it!

Best wishes,
Jim Shields
in sunny central Indiana (USA)

Jim Shields             USDA Zone 5             Shields Gardens, Ltd.
P.O. Box 92             WWW:
Westfield, Indiana 46074, USA
Tel. ++1-317-867-3344    or     toll-free 1-866-449-3344 in USA

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