On 14 Jan 2003 00:14:41 GMT, (MMMavocado) wrote:

Plants in many families can make fruit parthenocarpically (seedless fruit is
the result, so for a fruit grower that's still ok, but not reproduction). But
if not parthenocarpic, even fruits won't form.
Examples of dioecious plants that come to mind a

date palms (Phoenix dactylifera)
persimmon (Diospyros virginiana, D. kaki)
red maple (Acer rubrum)
Some hollies (not all) (Ilex spp.)
at least some of the ashes (Fraxinus spp)
papaya (Carica papaya), which has staminate, pistillate, and perfect-flowered
individuals
Some grapes, including the southern muscadine (Vitis rotundifolia), which, like
papaya, has all three types.
fig (Ficus carica), although females are often parthenocarpic, and of course,
the syconium is not really "fruit" tissue anyway, in the sense of being an
ovary.
Brazilian pepper (Schinus terebinthefolia)

In most of these examples, except for some horticultural cultivars selected for
their parthenocarpy, an isolated pistillate ("female") plant will not bear
fruit.




Question: re. the Solo Papaya grown widely in Hawaii. I was told the
normal spawn was one third Female, two thirds bi-sexual. My guess was
that the males had a fatal gene and died. Is this correct?

I liked the fruit from the female trees better, but it was much less
available.


_

- Charles
-
-does not play well with others

On Mon, 13 Jan 2003 19:09:23 GMT, "P van Rijckevorsel"
wrote:

Isn't there any number of fruit trees who need to have a 'male' planted
somewhere near them for them to bear fruit? Maybe I can think of them when
feeling a little less woozy.
PvR

cra2 schreef
So, if I moved a female plant, for example, to an area of the country
where no plants of the opposite sex existed, the plant could not reproduce,
correct?

Can you name any specific examples? Are there are any commonly known
instances of this... where you have to have an "opposite sexed" plant
somewhere in your neighborhood or the plant won't reproduce?




ginkgo

The cycad you refer to is actually a "male" clone of Encephalartos
woodii. It is apparently extinct in the wild but the surviving clone
has been propagated and as many as 500 specimens exist in botanic
gardens and private collections.

There are efforts to propagate E. woodii by tissue culture, to induce
a sex change to produce a "female" clone, and to breed a "female" by
first crossing with a closely related species and then repeatedly
backcrossing to the "male" clone.

Some people question whether E. woodii was ever a widespread species.
It may have been a single individual that arose as a intergeneric
hybrid. So maybe they never were any "females."

Reference

SEX CHANGE IN CYCADS - HOPE FOR WOODII?
http://www.plantapalm.com/vce/biology/sexchange.htm


David R. Hershey


"P van Rijckevorsel" wrote in message ...


+ + +
To pick more nits: it is debatable if the option to be propagated still is
reproduction. IIRC there is a species of Cycad of which only a 'female'
specimen is known (perhaps it is in Kew?), so as a species it is just about
extinct.
PvR

Thanks. This looks like it. Nice link!
PvR

==============
David Hershey schreef
The cycad you refer to is actually a "male" clone of Encephalartos
woodii. It is apparently extinct in the wild but the surviving clone
has been propagated and as many as 500 specimens exist in botanic
gardens and private collections.

There are efforts to propagate E. woodii by tissue culture, to induce
a sex change to produce a "female" clone, and to breed a "female" by
first crossing with a closely related species and then repeatedly
backcrossing to the "male" clone.

Some people question whether E. woodii was ever a widespread species.
It may have been a single individual that arose as a intergeneric
hybrid. So maybe they never were any "females."

Reference

SEX CHANGE IN CYCADS - HOPE FOR WOODII?
http://www.plantapalm.com/vce/biology/sexchange.htm

David R. Hershey

This sort of thing happens in botany too. A somewhat similar case is that of
the St Helena redwood (extinct in the wild) and the St Helena ebony (down to
two specimens in the wild), of which hybrids are doing well

http://home1.swipnet.se/~w-17282/endemic/ebony.html
http://home1.swipnet.se/~w-17282/endemic/redwood.html

PvR

=============
to breed a "female" by first crossing with a closely related species
and then repeatedly backcrossing to the "male" clone.

Iris Cohen schreef
I understand similar efforts are underway to preserve a species of bird of
which there is only one left.

Iris,