[Taxacom] "Tenuinucelli" clade in eudicots?

Kenneth Kinman kennethkinman at webtv.net
Fri Feb 25 21:55:12 CST 2011

Hi Richard,   
       Well, you clearly did not answer my question, but just criticized
the phrasing of my question.  Okay.   So in consideration of your
criticism, I would instead ask it a little differently.  Is their any
strong evidence which supports a "theory" that the tenuinucellate ovules
of Order Cornales are synapomorphic with the tenuinucellate ovules of
euasterids?  And if so, is there any evidence supporting the theory
(reflected in Peter Stevens' APG website)  that Order Ericales is
actually closer to the euasterids than Order Cornales?         
        Below is the relevant part of a post by Les Watson which seems
to indicate the view that tenuinucellate ovules are synapomorphic for
the clade "Tenuinucelli" (inclusive of Cornales), although it does not
address the internal phylogeny of that clade (whether Cornales or
Ericales are closer to euasterids).  Over 11 years later, it seems
appropriate to zero in on  which tenuinucellate group (Ericales sensu
lato or Cornales) is the immediate sister taxon to the euasterids).                 
        Unfortunately, the APG website does not seem to address either
the evidence or theory that evaluates the possibility that Order
Cornales could be the immediate sister taxon to the euasterids
(exclusive of their Ericales). But admittedy, if the tenuinucellate
ovules of  Cornales could be shown to be clearly distinct from those of
Ericales and euasterids, then that would be a whole different matter.
This has bothered me for several years now, and I would finally like to
know why the APG website continues to show their clade [Ericales (sensu
lato) + euasterids] characterized by tenuinucellate ovules, but does not
address the fact that Cornales also have tenuinucellate ovules (which
Watson, below, seems to believe is synapomorphic for the whole grouping
of APG's "asterids", including both Cornales and Ericales).               
Les Watson posted on Taxacom in 1999:
       An update of our 'Angiosperm Families' package has been posted at
the DELTA Web site, at 
This version incorporates the classification of Flowering Plant Families
presented by The Angiosperm Phylogeny Group (APG) in Ann. Missouri Bot.
Gard. 85, 531-553 (1998). Their classification into ordinal and
(informal) supra-ordinal groups reflects recent, far reaching molecular
phylogenetic studies. It has appeared without group descriptions, but
inclusion in our package makes it easily accessible (along with earlier
classifications) for detailed research into morphological,
phytochemical, etc., character state correlations, and for preparing
comparative group descriptions, via our family descriptions in
association with Intkey and other DELTA facilities. 
The appended natural-language descriptions for the 'Asterids' and
'Rosids' series of the APG's 'Core Eudicots' have been generated using
Intkey and Confor. To conserve space, they are restricted to a small
suite of the characters showing different tendencies in these two
groups. They exemplify the feasibility of preparing comparative
descriptions via the present package, and the opportunities available
for researches into intra-group variation by extended applications of
Intkey to our descriptive data. Ordinal descriptions may be expected to
display less intra-taxon variability than is apparent at this level. 
The SUMMARY option of Intkey generates character-state distributions for
any grouping of families, using all the available characters or selected
character suites. This takes no more than a minute or two for any
grouping that is directly built into the current package, and preparing
one for any other series of families requires only that the user first
selects their names. Automatic conversion of the data into
natural-language descriptions, in RTF or HTML format, may be performed
by applying Confor to the Intkey output. 
The following tables (obtained using Intkey) also compare the APG Rosids
and Asterids groups, our Tenuinucelli and Crassinucelli (this package,
cf. Young and Watson 1970) and Cronquist's (1966, 1981) subclasses, in
terms of family compositions. 
               Tenuinucelli Crassinucelli Unassigned 
Asterids _____    98 _____      0 ______    2 
Rosids  ______     0 ____     149 ______    0 
Unassigned *1      2 _____     31 ______    2 
Unassigned *2      8 _____     90 ______    6 
_______      Asteridae Rosidae  Magnoli. Hamamel. Caryophyll. Dilleni. 
Asterids ____  46 __    29 ____ 1 _____  1 _____  0 _____ 23 
Rosids  ____   0 __    88 _____ 1 _____ 18 _____  0 _____ 42 
Unassigned *1 _  0 __    10 ____ 0 ____  2 _____ 15 _____  8 
Unassigned *2 _  0 __    25 ____ 39 ____  7 ____ 15 ____  18 

*1 APG Core Eudicot but neither Rosid nor Asterid 
*2 APG Oddment family, or basal order, or family of uncertain position
at the highest group level; or Eudicot but not core Eudicot; or core
Eudicot but neither Rosid nor Asterid 
The first table shows that the APG Asterids are to all intents and
purposes the Tenuinucelli, while their Rosids are the Crassinucelli
minus 19 families they assign to 'basal orders' and numerous others they
leave unclassified. The Asterids also compare quite well with the
Sympetalae (Metachlamydeae, Gamopetalae) of Nineteenth Century systems
(e.g. Bentham and Hooker, 1883; Engler and Prantl, 1892), while the
Rosids are recognisable as a restricted version of Engler's
By contrast, the second table shows how poorly the APG groupings compare
with the pseudo-phylogenetic subclasses Asteridae, Rosidae, Dilleniidae,
etc., and the two tables clearly demonstrate that 'Asterids' and
'Rosids' are infelicitous names. When the impending, overhauled
classification of the Flowering Plants is formalised, it would surely be
appropriate to acknowledge nomenclaturally the astuteness of the
Nineteenth Century taxonomists who detected important groups without the
benefits of embryology and molecular biology, and with little or no
regard for evolution. 

More information about the Taxacom mailing list