Angraecum leonis- browning spur, blasting bud question

[bethmarie]

This plant has a tendency toward bud blast, but this year it has a bumper crop of spikes and buds in various stages of development.

Over the last couple of days, the most mature bud, top left in the pics, has developed browning in the spur.

I suspect the bud connected to that spur may be on it's way to blasting too--the yellow is suspicious- but what I'm curious about is if you have are theories regarding what is happening to the spur.

The only flower that has opened so far also had a stretch of brown in the spur, so the browning spur and blasting bud aren't necessarily connected.

[estación seca]

Did some reading, and found out I've been to the Madagascar habitat... but didn't know that at the time.

Do you have the smaller Madagascar plant, or the larger Comoros Islands plant?

Diego Suarez, on the Indian Ocean at the northern tip of Madagascar has a minimum relative humidity of 65% during the long winter dry season, when there is neither rain nor dew. As you see, the plant blooms during its winter dry season. Humidity is even higher during the summer rainy season. I would be afraid to not water this plant for months on end, but that is what happens to it in the dry winter back home. The forest is a mix of evergreen and deciduous, so light will also be brighter in the winter. Winter days are into the 80s F / 20s C and nights rarely below 70 F / 20C.

Companion plants are various sun-loving, dry-winter Bulbophyllum; Pachypodium baronii, geayi and windsorii; several spotted-leaf Oeceoclades; the flamboyant tree, Delonix regia; baobabs Adansonia perrierii and suarezensis; and multiple really weird Euphorbias like E. pachypodioides.

From my reading, the larger Comoros plant grows at higher elevation, which means cooler, and is moist all year.

Angraecum leonis - Lion's Moustache Orchid - Angraecum Encyclopedia

[bethmarie]

Thanks for your thorough and thoughtful reply, estacion.
I have the Comoro variety--the smaller Madagascar variety is particularly rare in trade and- due to land development-becoming by the day more rare in its native environment.

After watching this one spike and blast since 2012, I read a few months back that it can be sensitive to temperature changes when blooming.
I moved it from the rack in front of the windows to the rack against an interior wall, and it has gotten further this year than any other. One flower, and many buds, though it remains to be seen how many buds will make it all the way.

I'm just scratching my head over what would cause the browning on the spur, and the (likely) blasting of the bud attached.

[estación seca]

My best guess would be low humidity. Based on reading, the Comoros Island plant is in a high-elevation wet forest.