Bulb Definitions

[fisher60]

This may sound very silly but what is the difference between a Psuedobulb and a Backbulb? I wanted to try starting a new Cymbidium and the propagation instructions I found tell me to use a "Backbulb"?

[King_of_orchid_growing:)]

Backbulbs are old pseudobulbs.

A pseudobulb is a swelling of the stem in epiphytical orchids and certain terrestrial/semi-terrestrial orchids (if they're in terrestrials and semi-terrestrials, then this structure is above the ground) that is used as a means of food and water storage.

As the name implies, pseudobulbs are not true bulbs. They are above ground modified stems. True bulbs are modified underground leaves.

[trdyl]

A backbulb is a pseudobulb. The backbulbs are furthest from the growing lead. They can produce new growing leads as long as they have viable eyes and you can keep them alive long enough. Usually the roots on backbulbs are not the best. But under the right conditions once the main leads are severed will start putting out growth form the dormant eyes.

[fisher60]

Originally Posted by King_of_orchid_growing:)

Backbulbs are old pseudobulbs.

A pseudobulb is a swelling of the stem in epiphytical orchids and certain terrestrial/semi-terrestrial orchids (if they're in terrestrials and semi-terrestrials, then this structure is above the ground) that is used as a means of food and water storage.

As the name implies, pseudobulbs are not true bulbs. They are above ground modified stems. True bulbs are modified underground leaves.

Thanks. Then in my Cymbidium, the backbulb is the psuedobulb that produced the fower stem?

[fisher60]

Originally Posted by trdyl

A backbulb is a pseudobulb. The backbulbs are furthest from the growing lead. They can produce new growing leads as long as they have viable eyes and you can keep them alive long enough. Usually the roots on backbulbs are not the best. But under the right conditions once the main leads are severed will start putting out growth form the dormant eyes.

Thanks Ted. I'd like to try starting another Cymbidium and wanted to make sure I understood the terminology.

[King_of_orchid_growing:)]

Originally Posted by fisher60

Thanks. Then in my Cymbidium, the backbulb is the psuedobulb that produced the fower stem?

I guess it would be if the spike is coming out from the older pseudobulbs.

[fisher60]

The plant originally had 2 spikes. 1 in flower, the second never did open any of the buds. And it only has 2 bulbs. I have no clue if the spikes were on the original bulb or not. Others have since told me not to try to divide the plant until it gets much bigger. 4-5 bulbs. I did repot it because the roots had grown up out of the pot. I had to cut the pot open to get it out. I know most orchids like to be crowded but this one appeard to be strangling. Now I believe I'll leave it alone and hope it makes it through the summer and re-blooms again this fall.

[WhiteRabbit]

Originally Posted by fisher60

The plant originally had 2 spikes. 1 in flower, the second never did open any of the buds. And it only has 2 bulbs. I have no clue if the spikes were on the original bulb or not. Others have since told me not to try to divide the plant until it gets much bigger. 4-5 bulbs. I did repot it because the roots had grown up out of the pot. I had to cut the pot open to get it out. I know most orchids like to be crowded but this one appeard to be strangling. Now I believe I'll leave it alone and hope it makes it through the summer and re-blooms again this fall.

good call!
Ideally any divisions should consist of 3 pbulbs and a new growth. That said - bigger is better! I don't divide plants unless they would become too big to manage, or someone specifically would like a division, and the plant is large enough for me to feel comfortable doing so.

As to your 'back bulb' question - with cyms - to me at least - this generally refers to old leafless pbulbs, that are generally covered by dead bract foliage giving the appearance the the pbulb is dead. When a cym has sufficient newer growth, these old back bulbs can be removed and propagated. The back bulbs themselves won't grow roots or bloom, but new growth will start. It can be a few years before these become bloom size.

[fisher60]

Originally Posted by WhiteRabbit

good call!
Ideally any divisions should consist of 3 pbulbs and a new growth. That said - bigger is better! I don't divide plants unless they would become too big to manage, or someone specifically would like a division, and the plant is large enough for me to feel comfortable doing so.

As to your 'back bulb' question - with cyms - to me at least - this generally refers to old leafless pbulbs, that are generally covered by dead bract foliage giving the appearance the the pbulb is dead. When a cym has sufficient newer growth, these old back bulbs can be removed and propagated. The back bulbs themselves won't grow roots or bloom, but new growth will start. It can be a few years before these become bloom size.

Well, to me, the plant looks great. It currently is staked out in between a ring of African Walking Iris's beneath a grandfather oak. This to shade it the entire summer while waiting for our fall which is normally mid to late November. I know it likes plenty of light but here in Fla, light is heat. Now if I don't forget to water & feed it occassionally.