Are Phals really Monopodial

[RosieC]

Ok, bear with me, my thoughts have wandered on this subject over several months. I have very little biology knowledge so I'm very likely missing a key thing here

Everything I have read says that Phals are Monopodial while orchids like Phaps are Sympodial.

Now as far as I can tell from the internet...

1. Monopodial means they grow from a single growth point.

2. Sympodial means they have multiple growth points and in botanical terms it also means that the "apical meristem is terminated" which as far as I can tell means the growth of each of the growth points will come to an end, often in a flower spike or will just abort.

OK so on the surface this matches BUT...

1. Phals grow basil Keikis. Are these REALLY keikis or are they just a new sympodial growth. Because we are conditioned to believe that Phals are Monopodial we seperate them and assume they are keikis. Maybe orchids like Phals are just less prone to new sympodial growths than ones like Paphs.

2. Phals can grow 'terminal spikes' which bring the growth point to an end. I have read that some people believe that a basil Keiki is more likely when this happens. So again, is it just that Phals grow a lot lot longer before terminating, or are more likely to grow for a long time before terminating, than something like a Paph. Sympodial orchids like Dendrobium can flower out the side as well as out the top, just like Phals do

This is the sort of thing I wonder about when I can't sleep.

[King_of_orchid_growing:)]

Wow...what a question.

I don't know!

The way I think about this is that people are the ones who like to classify things in a nice and neat way. This is how our mode of recognition and memory works by the way (sorry, don't know details, I only took psych as supplemental learning).

Nature, however, always likes to throw curve balls. That's why I don't bother with "monopodial or sympodial".

I'm more concerned about:

rambler?
pendulous?
upright?
"non-directional"?
clumping?

Stuff like that.

But good question!

[jkofferdahl]

I think Phals are really monopodial. There are exceptions to every rule, of course.

[orkie]

So my understanding (but I'm not an expert, so please let me know if if I'm off here!):

Phals are really monopodial...they belong to the vandaceous alliance, of which all plants are monopodial (right?). Some, like phals do make keikis/multiple growths...but so do Neofinetias, Ascocentrums, and others (please correct me if I am wrong though in some way!). Additionally, I am under the presumption that monopodial and sympodial orchids can never cross...you never see a phal catt hybrid-I think the podial-ness has a lot to do with that and is just a part of why they are not closely related (obviously flower features have a lot to do with that as well).

Also, though a phal can make a keiki, it doesn't have to in order to keep growing/flowering, it can just keep going up if there are no problems, but for a sympodial to continue growing, it does need to make additional pseudobulbs, once the bulbs have matured, they don't later begin growing again (to the best of my knowledge!).

You might want to think about the plants as far as alliance rather than whether they are mono or sympodial, such as catt alliance, vandaceous alliance, etc.

There are probably other things I am not thinking of as well here, I hope my thoughts help though!

Sara

[orkie]

A side note that is related: Something I've been wondering is, are any monopodial orchids found in the Americas? I am under the assumption that all vandaceous/angraecoids are in Africa, Asia, and the South Pacific.

Are there any other monopodials that are native to the Americas?

Oh, I may have just answered my own question! Vanilla seems to qualify!? But does anyone know any others? What about ghost orchids? Are they considered monopodial...since all they have are roots???

Sara

[quiltergal]

The key difference between the two which has not been pointed out yet is the existance of a rhizome that connects the many growths of a sympodial plant vs no rhizome on a monopodial plant. Some rhizomes are larger/longer and more visible than others. They are quite obvious in many Bulbos, Catts etc, while almost (not quite) invisible in other such as Paphs.

[Psyguy10]

Thats an interesting point you've brought up, Rosie!

My vote is monopodial: basel keiki's are normally produced when the mother plant can no longer grow as it should. (survival mechanism ) Terminal spikes are produced mainly on hybrids i believe(?) probably due to some genes flipping out on each other.

but maybe i shouldn't be in this discussion... because quite a few of my phalaenopsis are

[BikerDoc5968]

Rosie, this query is just too much to think about during the summer months... maybe you should think about more mundane things when you can't sleep.... you could always see if I'm up and on the computer seeing as there is 5 hrs difference... well, with day light savings it's only 4 hrs.

[Ray]

BINGO, Terri!!!

The existence of a rhizome is the key.

[orchidbingo]

Rosie,

I don't want you to stay up nights losing sleep so I'll try to help you sleep so ...

Sympodial growth occurs where the apical meristem ceases activity annually and growth is continued by a lateral bud.on the horizontal rhizome-- underground stem. When the apical meristem stops growth, the levels of IAA auxin (plant hormone) drops. Apical buds require much higher concentrations of auxin to grow than do lateral buds. Lateral buds growth is actually supressed by high levels of auxin because they are much more sensitive.

Are you sleepy yet?

In monopodial plants, where the apical meristem grows continuously, the apical bud remains dominant (apical dominance) because the presence of high levels of IAA necessary for its growth keep the lateral buds dormant-- remember that lateral buds are more sensitive to IAA and too much suppresses growth. If you destroy the apical bud then you recreate the sympodial IAA conditions. Monopodials with damaged apical buds have greatly decreased IAA and this stimulates growth of the lateral buds along the stem (just doesn't happen to be underground)

If your are still not sleepy, something must be seriously wrong. This method ALWAYS works with my students!

bingo

P.S. How many more times can I post before I turn into a pumpkin?