[Taxacom] A small nomenclatural detail?

[Paul van Rijckevorsel]

----- Original Message ----- 
From: "Bradley Boyle" <bboyle at email.arizona.edu>
Sent: Thursday, September 15, 2011 8:24 PM

> Thank you, Paul, for that tidy clarification.
> 
> So, is it correct to say that any time I see square brackets  
> in the author of a botanical name, that author is incorrectly 
> formulated under the current ICBN?

***
Yes, it is an incorrect author citation.
* * *

> Regarding the use of "ex" in plant names, is the author
> preceding the ex an optional honorific, intended to 
> acknowledge the person who suggested but did not 
> (validly) publish the name? Or is it required?

***
The use of an "ex" citation is optional. Both provisions 
that deal with this matter (Art. 46.4 and 46.6) use 
"may be [inserted/added]".
* * *

> In other words, are
> 
> Prunus dulcis Mill. ex D.A. Webb
> Prunus dulcis D.A. Webb
> 
> valid alternative formulations of the same name? Or not?

***
Both ways are allowed, equally (although, obviously, the
example itself is spurious).

Paul

P.S.
    Prunus dulcis D.A.Webb    and
    Prunus dulcis (Mill.) D.A.Webb 
are not equal as the author in parentheses is not 
optional (Art. 49.1).