Product of insomnia or Mimbulus Mimbletonia

[mooseming]

Mimbulus Mimbletonia: what's in a name?

Mimosa = aka the sensitive plant 
Nimbus = aura

Mimbus = sensitive to auras

Things we know:

Neville was given the plant by Uncle Algie, it is rare.
Harry, Luna, Ginny and Neville were all blasted with stink sap from 
the plant and Ron and Hermione were not. 
Harry, Luna, Ginny and Neville all `hear voices' by the veiled 
gateway whilst Ron and Hermione don`t.
The veiled gateway `kills' people, manner unspecified.
In the Potterverse it is possible to separate the soul from the body.
Ollivander did a bunk shortly after Neville visited his shop to buy 
a new wand.
Ollivander had an old wand in display in his window.
Voldy likes to use the founder's items to make HRX.

Pure speculation:

Ollivander's display wand was Rowena Ravenclaw's and therefore is a 
HRX contender.
Ollivander's departure was a direct result of Neville's visit.
Neville said or did something to precipitate this, perhaps show an 
inconvenient interest in the display wand for example.
Harry, Luna, Ginny and Neville all heard voices at the veiled 
gateway as a result of being stink sapped.
These are the voices of the dead, souls separated from the body 
passing through the veil.
If Neville is sensitive to separated souls in the veiled gateway he 
might also be sensitive to a bit of soul lurking in a HRX.
The locket mentioned in the clearout of Grimmauld Place is that of 
Salazar Slytherin and also a HRX contender but the stink sapping 
occurred after interaction with the locket and therefore could have 
passed undetected.

Result:

Hooray! no need to randomly vandalise every ancient relic in the 
magical world, simply wave suspect item at a `diviner' and quicker 
that you can say CAT scan instant HRX detection.

Added value:

Voldy needn't know this, of course it all depends on where 
Ollivander has gone
..

Regards
Jo