cotyledon number request

Una Smith una.smith at YALE.EDU
Mon Nov 27 21:04:25 CST 2000


Finn Rasmussen wrote:

>>It seems to have escaped Watson and Dallwitz that in the largest monocot
>>family (Orchidaceae, about 1/3 of the monocots) there are no cotyledons at
>>all.


Eric Zurcher wrote:

>I think that's being a bit unfair to Watson and Dallwitz - I am sure the
>situation in the Orchidaceae has not "escaped" them. Taking a quick look at
>the data set, it appears that Orchidaceae is one of the families for which
>cotyledon number is not coded (equivalent to "unknown"). Actually, the
>relevant information is dealt with in another character, which indicates
>that within the Orchidaceae, the embryo is (usually) rudimentary at the
>time of seed release.

I think it is very unfair.  Mike Dallwitz is responsible for putting the
data on the Internet in a highly useful manner for many years now.  I got
my first copy in 1994 via anonymous FTP...  Les Watson is responsible for
the data content, and in my correspondence with him over the past 6 years
he has consistently demonstrated an extraordinary knowledge of morphology
and anatomy that is both deep and broad.

That said...the intro blurb to the database in question explains a very
important design issue for comparative databases in general:  where the
range of documented variation in a character is seriously inadequate, or
problematic in some other way, it is better to leave the character not
coded (i.e., "unknown").  This is especially true for large taxa, which
group certainly includes Orchidaceae.  For more about this design issue,
see:

   Watson, L., and Dallwitz, M.J. (1991). The families of angiosperms:
   automated descriptions, with interactive identification and
   information retrieval. Aust. Syst. Bot. 4, 68-195.

        Una Smith




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