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
fragment.

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:
http://shieldsgardens.com/amaryllids/…

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)

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