Are they nobile type Dendrobiums?

1 is Dendrobium nobile virginale. The other is Dendrobium simillaea.

Is this the second orchid?Dendrobium smiliae?
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If so, it is an orchid that comes from the far north of Australia and requires a warm dry "rest" in winter to simulate the wet and the dry seasons. I have not attempted to grow it in the heated glass-house needed here whereas Den. nobile requires the same winter "rest" here that is provided by growing in a shade-house and mostly relying only on the natural rainfall that falls.
To sum up (For Here)
Den.smilliae = Difficult
Den. nobile = easy (a beginners orchid)
Now you need some decent advice from the real orchid growers who live in Northern USA.
In my opinion this bone dry stuff in the rest is overdone, drier with increased light is more on the money.

This post was edited by arthurm on Sat, Jan 25, 14 at 19:02

Just found this old thread that may help re Den. smilliae. Lots more info re, nobile types of Den available in old threads.

Here is a link that might be useful: Previous Garden web discussion

I think you are right about bone dry, It's pseudobulbs have shriveled alot. The nobile not so much.

You're supposed to cycle them in and out. I only give mine 6 weeks of rest and do it later so that midway through is the winter solstice. I don't supplement lighting so they respond to the seasonality changes more. Plus in the central heating I think 8 weeks may be too much. I have a nobile but have no idea what to do with the smiliae. I hope that helps, I'm on the Canadian side of Detroit.