Worrying to realise how much of this I've forgotten!!

1 a, maybe also c
2 c and d ??
3
4
5 d
6 agree does seem to be a and d
7 probably dead ;-)
8 a (I think!)
9 a (I think!)
10
11
12 d
13 c

riverminty, welcome to the world of learning. It is strewn with questions. These can be answered and/or explained. You will choose which you want and you will find your particular response. I wish to commend to you the Chinese proverb, "Give a man a fish and you feed him for a day. Teach a man to fish and you feed him for a lifetime."
Learn to research. You will need the ability for the rest of your life.

When I was a teenager, my bio teacher told me prokaryotes can reproduce sexually, but now I'm not sure if she was referring to plasmid exchange.

I have another botany question: is "polyembryonic" synonymous with "chimeric"?

I was thinking just what Ronalawn82 wrote, but could not have expressed nearly as well.

Joanie, I'm wondering if there is something more to your question than first appearance or if the question is misworded. The terms "polyembryonic" and "chimeric" are completely different. And, unless I'm missing something, I don't even see any similarities.

I was confused about whether a polyembryonic seedling was the result of many embryos combining into one organism.1 Mostro said the sprouts from a polyembryonic seed are their own organisms, so that would be a no. So the remaining question is: are all the embryos in a polyembryonic seed identical? I read somewhere that if polyembryonic seedlings are allowed to remain together, they don't need a pollenizer, so I suppose that would be a no, too, but I don't know if whoever wrote that had any experience or academic knowledge of such things. (Besides, don't plants know who their siblings are?)

1. While we're on the subject, is there a word for this that distinguishes it from other forms of chimerism, such as maternal stem cells joining with fetal stem cells?

I have read online some time ago that citrus seeds are polyembryonic and that only one seedling was the result of cross pollination. The others are supposed to be identical to the mother plant. I don't have any journals or support, bust I'm just throwing it out there if it. Chunerism I believe, is when the parent cells fuse and every one keeps their own traits. The resultant is something that is not as stable genetically. Some cannas exhibit chimerism and are prized for this genetic unstability because each leaf may be different.

Polyembryonic plant seedling are the result of a single fertilized egg splitting into two or more identical embryos (similar to polyembryony/identical-twining in animals) . The result is genetically identical offspring, and those offspring would only be sexually compatible if the individuals themselves were self-fertile.

Chimerism is the combining of two or more genetically different groups of cells.

BTW, interesting article about plant sibling recognition, but I don't think it has anything to do with whether polyembryonic plants are sexually compatible.

Origami, were you referring to this?

Brandon, are you sure you don't mean that only the embryos from the maternal cells are identical? That would explain why two self-sterile adults from the same seed can cross-pollinate, if they need only to be nonidentical, not dissimilar.

Brandon is referring to the case where multiple embryos are all derived from the same zygotic embryo (cleavage polyembryony). All the embryos would therefore be genetically identical.

I believe you are thinking of the situation where multiple egg cells within the same ovule are fertilized independently (simple polyembryony). Typically the eggs are all derived from the same cell, but provided the male donated gametes are different the resulting embryos would not be genetically identical.

Either, neither, or both can occur in the same seed. Most often only the dominant embryo survives. Chimerism is very unlikely to occur under natural conditions but may arise when embryogenic cultures are established from polyembryonic seeds.

Actually, I was referring to the opening of the article I cited. "Citrus exhibits polyembryonic seed development, an apomictic process in which many maternally derived embryos arise from the nucellus surrounding the developing zygotic embryo." (Emphasis mine)

Also, according to EXTENTO, "Polyembryonic mango varieties, like the so-called common or Hawaiian mango varieties, produce two or more plants of nucellar (maternal) origin from each seed. These plants are predominantly true to type, and may be grown from seed without the necessity of grafting."

So I suppose now I'm left with the question of whether the nucellar embryos are clones or parthenogenic. I'd probably know that if I paid more attention to biology in high school. Is the nucellus haploid or diploid?

The nucellus is derived from sporophyte tissue so it is diploid. The nucellus normally produces a megasporocyte which eventually undergoes meiosis to form four megaspores. Usually only one of the megaspores survives to become the female gametophyte that subsequently produces eggs.

When embryos are derived from the nucellus it is called nucellar embryony, a type of sporophytic apomixis. These would be clonal because they are produced asexually. This is different from parthenogenesis which is when an embryo forms from an unfertilized egg.

Unfortunately they don't allow you to edit posts here. I should probably clarify that both apomixis and parthenogenesis both produce offspring asexually. The only difference is the donor tissue.

Thanks. I could really use a refresher course!

HELP! IVE KILLED ALL MY BEES.I BROUGHT MY JAMINE PLANT IN FOR WINTER AND EVERY FLOWER HAD A BEE STUCK IN IT.THEY HAD GONE IN TO GET POLLEN AND GOT STUCK HAS ANYONE EVERY HEARD OF THIS? IS IT LIKE A FLY EATING PLANT? I ACTUALLY FEEL BAD FOR THEM.

pennyroyal1961, I don't have a good answer but I found some interesting tricks which flowers play on bees at this site..
http://library.thinkquest.org/C002061/textversion/txtfnf.htm

Pennyroyal1961,

I noticed you're new to Gardenweb. Welcome and I hope you find it to be a helpful and fun place.

I don't have any answer to your bee question, but would like to offer three suggestions:

1) Please start your own thread when asking questions not directly related to the original post. There are many reasons for this including:
a) It's very confusing when someone starts there own conversation within another conversation.
b) The original poster is now getting responses to your post emailed to them, clogging up their email with answers to your question.
c) You are not getting the answers emailed to you because your question is in another thread.
d) It is much harder to find information when searching for information when threads have multiple topics intermixed.

2) Try to post your questions to relevant forums. For instance you could post your question above to the Bees & Beekeeping Forum (linked below).

3) Don't type in all caps. It is considered rude and/or shouting by many.

Here is a link that might be useful: Bees & Beekeeping Forum