Angraecum rutenbergianum and A. didieri

[naoki]

I got these two plants labelled as A. rutenbergianum (Ar) and A. didieri (Ad) from Madagascar Import of Louisiana Orchid Connection. I posted an earlier photos of this particular Ad in this thread. There are quite a few differences between these two plants. The differences of these two species have been debated, but I usually end up confused.

Measurements (Length x width in mm):

A. rutenbergianum

• DS 25x8
• LS 27x8
• petal 24x4
• Lip 31x21
• spur 140 (length)
• Ovary 40x3
• peduncle 6 (length)
• leaf 70x7

A. didieri

• DS 38x9
• LS 38x7
• petal 32x5
• Lip 35x24
• spur 145 (length)
• Ovary 28x5
• peduncle 16 (length)
• leaf 60x14

Ar (right), Ad (left)



Note Ad has much longer internodes (distance between the leaves). Also Ar has a longer and skinnier ovary. But Ar has shorter peduncle (the stem between the stem and ovary).
Ar (left), Ad (right)


The angles of the lateral sepals seem different. Ar has a flatter lip near the base.
Ar


Ad


From this angle, you can see the difference in the curvature of the lip near the column.
Ar


Ad

 

[naoki]

(Continued)

Ad's flower is older, so the anther cap is a bit shrivelled, so I'm not sure if there is a difference in the shape. The angles are slightly different, but there may be slight difference in column shape. Ad seems to have side-lobes stretching down further.
Ar


Ad


Ar


Ad


Ar has much smoother root texture. These are newer roots which developed in my grow tent, so they are in the same environment, and retained the original characteristics at the time of import.
Ar


Ad


The leaf shapes are really different with narrower leaves of Ar. The color and texture are different. Ad has pits like things on the leaves, and they are more noticable.
Ar


Ad

 

[Ozpaph]

'splitters'???

 

[abax]

Interesting differences that I wouldn't have noticed without the
excellent photographs.

 

[Herbert]

In ORCHIDS of Juni 2017 Hermans writes about the group. Summarizing he says, that didierii is a species with a rather long stem and nowadays not? in culture!
Your plants all seem to be rutenbergianum; but perhaps this is a complex with some species hiding behind that name...

 

[NYEric]

Great photos.