Two questions from current online AOS Bulletin

[Brooke]

These are questions concerning Phals - first question

.

My phalaenopis has a bloom spike arising out of the apical crown of the plant. What effect will this have on future flowering?

A.

Probably this means that your plant has reached full maturity, and it will cease to grow and flower after this spike is finished. However, we've seen some plants resume growth, and thenceforth act in a normal manner. Some say this atypical flowering results from too much light; others blame insecticides, especially the systemics. A plant that does not resume normal growth will usually throw one or more new plants or "keikis: from the base of the plant, so don't throw it away. Until it does produce new plants, continue to treat it in a normal manner.


Second question

Q.

My phalaenopsis plant grows quite well, but doesn't bloom. Why?

A.

One reason could be too high temperature. We find that phalaenopsis flower quite well at 62 degrees F. If you are growing the plants indoors, artificial lights nearby might cause long days and thus inhibit flowering. If the plants seem to be growing well, water and fertilizer applied as directed, temperature ideal, and still no flowers, then not enough light is probably the answer. Gradually increase the light intensity until you have about 1000 to 1500 footcandles, or roughly all the light the plants can take without burning. If growing in the home, move the plants to a nice, bright windowsill that receives an hour or two of direct sun in the very early morning or late afternoon.


I thought these answers were very concise and very easy to understand. I hope it answers some of the often asked questions.

Brooke

[katrina]

Excellent post Brooke!! The info really does a great job of cutting out some of the "mystery" as well as dispelling some of the internet myths surrounding phals. Thanks for posting the info!!

[sunshine]

Excellent post I agree, very simple and too the point

[Ron]

My phalaenopis has a bloom spike arising out of the apical crown of the plant. What effect will this have on future flowering?

A.

Probably this means that your plant has reached full maturity, and it will cease to grow and flower after this spike is finished.

Never heard of this one before, I would suspect it is one of those nonsensical story often passed around.
Fancy a plant having a death wish!
Cheerio
Ron

[Brooke]

Good one Ron!

I had never heard of that either. I thought as long as you give a plant good culture it would live forever. Usually people giving advice in the AOS newsletters or bulletins is known within that species but I've deleted the newsletter and can't check the author.

I've never had a terminal spike but did have a terminal root once. Yup, a root grew right out of the middle of the crown. The plant did produce a basal keiki and continued to grow and bloom. It took about two years for the original growth to eventually die.

Brooke

[patticake]

I agree that those are good ?/answers. Thanks for posting those, Brooke.

[kip]

Originally Posted by Ron

Never heard of this one before, I would suspect it is one of those nonsensical story often passed around.
Fancy a plant having a death wish!
Cheerio
Ron

Not exactly a death wish - The apical meristem is what the new leaves are produced from. As the plant grows, the undifferentiated cells ("stem" cells) in the meristem begin to differentiate, and form the leaves. The apical meristem produces hormones to inhibit the growth of other meristems (the "nodes" on the stem). The primitive vascular system of plants is not efficient at carrying these hormones, so once the apical meristem has advanced far enough, the older nodes are no longer inhibited, and can then form a new apical meristem ("basal keiki" for phals), or they can begin to differentiate, and form floral meristems (spikes) or root apical meristems (new roots). If a phal is producing a spike from the crown, it means that the apical meristem has partially differentiated, and has been converted into a floral meristem. There is no longer an apical meristem to continue growth of new leaves. Under good conditions, the other meristems in the nodes can produce basal keikis. There are usually some undifferentiated cells left in the floral meristem, so it is also possible for it to form keikis from the spike.
sorry for the long winded explanation, but I hope it clears things up a little.

the credits for the Q&A from the AOS bulletin are below:
George P. Woodward, Jr. (Santa Cruz, CA)
reprinted from the American Orchid Society Bulletin - March 1968

personally, I've never heard of him, but given the 40+ years since the original publication, it's possible he's no longer around.

[Dendian]

To make an excellent technical discussion simpler for us newbies, lets see if I got it right.

When a Phal puts up a flower spike or root from the top it means it lost the "apical meristem" which grows leaves (and doesn't allow roots and flowers to grow) and will grow no further. After this the plant will either grow new plants ("apical meristems") from there or the flower spike might produce keikis. Also, it is possible that this might trigger the "nodes" futher down the plant to produce new plants ("apical meristems").

Did I understand correctly?

This might also explain why the flower spikes and roots only come out further down the center stem on the plant, the apical meristem there has been converted into a floral or root meristem now that it is no longer needed to produce leaves.

And why, if you apply "keiki" paste onto a spike it will grow keikis - because it converts the stem into an apical meristem. WOW

This is really neat, thanks.

[Ron]

When a Phal puts up a flower spike or root from the top it means it lost the "apical meristem" which grows leaves (and doesn't allow roots and flowers to grow) and will grow no further. After this the plant will either grow new plants ("apical meristems") from there or the flower spike might produce keikis. Also, it is possible that this might trigger the "nodes" futher down the plant to produce new plants ("apical meristems").

Interesting , unfortunately I have never read or heard of this happening.
In the plant world, many things grow weirdly when things go wrong.
If this happens in Phallies I suspect it is one in a million accurance as if it happen a lot they would no longer be such a popular grown plant.
Will keep my ears open!
Ron

[kip]

when you hear people talking about a terminal spike, that's generally what they're talking about. It's not a very common occurance, but it does happen in some species. and there's nothing to keep the plant from recovering, since the inhibitors that keep new growths from forming are gone.

[Brooke]

Thanks for the info Kip. I assumed they were referring to what we call a terminal spike.

Interesting they were asking the same questions in 1968 that are still being asked today.

Brooke