Shaine,

The seed size is more related to the size of the flower than the size of the plant. I assume you have put fresh pollen of the Alcantarea extensa onto the stigma of the Vr. hieroglyphica? It is very difficult to cross them the other way around, due to the floral parts being larger of the alcantarea - the pollen has a longer distance (than usual in nature) to travel down the style to the ovary. I've tried, and failed, even after performing micro-surgery on the style of the alcantarea in the wee hours of the morning when the stigma was receptive (around midnight 'til 3am).
Did you remove the anthers of the hieroglyphica flower before its pollen was ripe? If you did, then you might be successful with your bigeneric cross. If you did not, then sorry, but your seed pod is likely a "selfed" hieroglyphica. Does your hieroglyphica have other ripening seed pods? Both Alc. extensa and Vr.hieroglyphica are renowned for selfing - i.e. without human (or critter) intervention.

Either way, the seed will be about the same size for those two, successfully crossed or selfed. The fluffy parachutey parts of the extensa seed are a bit coarser than those of the hieroglyphica, and the actual seeds are slightly thicker and longer.
I think (?) that any bigeneric seed will be closer to the same size as 'normal' seed of the mother plant.

Do others agree?

I hope this hasn't confused you further!

Cheers,
Kerry

I can't see why the seed would be effected by the DNA they carry. The seed parent already has her DNA for producing seed and that shouldn't change with the introduction of pollen.

I second both of the above. The size of the seed produced by the mother plant is already determined, and will be the same no matter what pollen you put on it. Now, when that offspring matures, the size if its seed may be somewhere in between the two parents, assuming it's even fertile, which most bigeneric crosses aren't.

I'm not sure by your question if you think that a larger pod means larger seeds, but that is not the case either. If anything, it just means more of them.

Kerry also makes a good point about the possibility of self-pollination, particularly on Alcantareas.

Thankyou for your replies.The information is very useful. Kerry the pod plant is the alcantarea I removed the anthers before they open and the covered the stigma twice with the pollen. The pollen is very swollen ready to open.I have made several crosses in the past few months with lots of full seed pods forming.they say its easy for vriesea hieroglyphica to produce seed but I couldn't get one pod from my plant. Kerry I was a member of the gold coast bromeliad society but now I have joined the caboolture club now that I live up this way. Happy growing to all.

Kerry,
how do you know when a stigma is receptive?
Ali

Hey Ali,
When receptive, the stigma has a clear type of mucous blob on the end of it - looks rather like a dew drop on the end. From my understanding, this actually stimulates the pollen to travel down the (inside)length of the style to the ovary - allowing pollination to occur.
For bromeliads, this receptive stage differs between various genera (...and for human females!). As Lisa has advised, the stigmas of neoregelias are most receptive between 9 - 11am. Most broms are pollinated in the day time. However, many of the foliage vrieseas and alcantareas are, in nature, pollinated by night creatures eg. bats, moths, but also ants.
From my own experience, I have noticed some foliage vrieseas first get that sticky muck on their stigmas at various times of the early evening, through to about 2am. Well actually, many still have the 'blob' in the more people-friendly morning - I know of some hybridisers who still apply the pollen to the 'blob' in the early morning, with success.
When each flower first opens, the anthers have unripe pollen - it's hard and can't be removed. For a confident cross-pollination, it is best to remove the anthers before the pollen is ripe - to ensure self-pollination does not occur. (although not all broms self-pollinate). You know when the pollen is ripe when it can be easily removed and has the consistency of flour. The pollen is usually ripe before the stigma is receptive i.e. has the 'blob' on its end. You can cover the end of the stigma with fresh or stored viable pollen before it gets the 'blob', and this usually works too - as some pollen will still be on it at the receptive stage. I think you have more chance of successful pollination if you apply the pollen to the 'blob' either before or during the receptive stage - not after.
I have collected pollen of day-flowering vrieseas (usually the green-leaved ones) and tillandsias, and then applied it at night to those foliage vrieseas which don't open 'til the evening. I have also noticed that some foliage vriesea hybrids which have one green-leaved vriesea parent, are receptive in the late afternoon - in between the two parents.
Vriesea racinae opens its flowers earlier than I expected - more like around 5pm. Once, when I was eagerly awaiting the next flower, or pair of flowers, to open - I was running late for some social event, and was hanging out for it to open so I could remove the anthers and whack the stored pollen of another foliage vriesea on its stigma pre-blob (it only has about 6 to 8 precious flowers). So - I placed the small potted vriesea in a dark space at around 4pm, and sure enough the next 2 flowers opened earlier due to the less light...ha!

Hope this info helps Ali - and any others interested in the nitty-gritty. I learned much of this on this forum :)

And Hi to Shaine, now in Caboolture - good luck with your hybridising.

Cheers,
Kerry.

Thanks Kerry, that is useful knowledge. I have only tried crossing Dyckia x Deutercohnia so far, but I have a ripening seed pod...

Kerry's right, but for most Bromelioideae crosses you can just go pluck a flower at 10:30am and rip out the anthers and then rub them on any stigma you can find. You'll be right enough that you will soon have more seeds than you can handle. If you don't find yourself at home at 10:30am then you'll have to take your plants with you!