cassia taxonomy

S1.DAQ at ISUMVS.IASTATE.EDU S1.DAQ at ISUMVS.IASTATE.EDU
Thu Apr 10 09:34:41 CDT 1997


To clarify and add to Tom Lammers reply to Anita Cholewa's question about
Cassia and its segregate genera -- prior to Irwin & Barneby's revision of
Cassia (citation below), nearly all legume taxonomists accepted Cassia s.l.
This publication, however, gave good evidence (based on typical "Barnebyan"
critical examination of the stamens, bracts, fruits, seeds, etc.) for
splitting these genera, and a synoptic key is provided (pp. 2-3; too lengthy
to reproduce easily here).  So while Duane Isely's 1975 publication (in the
Mem. of the New York Bot. Gard., not Torrey Bot. Club) used Cassia s.l., his
more recent publications (e.g, legumes for the Vascular Flora of the
Southeastern United States, 1990) recognize Senna and Chamaecrista.  In this
latter treatment,  Isely derives the following key from Barneby's lengthy one:

1. Filaments of the 3 abaxial (lower) stamens sigmoid-curved and elongate;
leafstalk eglandular; trees......Cassia
1' Filaments of all stamens straight and shorter than the basifixed anthers
or no more than twice as long; leafstalk commonly glandular; shrubs,
herbs or trees.
2. Legume elastically dehiscent; bracteoles present on pedicel; stipules
persistent, conspicuously striate; herbs (- subligneous)....Chamaecrista
2' Legume indehiscent or inertly dehiscent; bracteoles absent; stipules
usually small and caducous, not conspicuously striate; herbs, shrubs,
and trees....Senna

In a forthcoming treatment of U.S. legumes, Isely uses shape of the fruit
segments and the pubescence of the ovary and plant for distinguishing S.
hebecarpa from S. marilandica.

The Irwin & Barneby citation:
Irwin, H.S. and R.C. Barneby.  1982.  The American Cassiinae:  A Synoptical
Revision of Leguminosae Tribe Cassieae subtribe Cassiinae in the New World.
Memoirs of the New York Botanical Garden Vol. 35, Part 1 (pp. 1-454) and
Part 2 (pp. 455-918).

(and neither Irwin/Barneby nor Isely list a "Chamaecrista hebecarpa" in
synonymy)

Deb

At 12:13 on Wed, 9 Apr 1997 "Thomas G. Lammers" <lammers at FMPPR.FMNH.ORG> wrote:
>At 09:57 AM 04-09-97 CDT, Anita Cholewa wrote:
>>Taxonomy question for the day...
>>I recently was confronted by our agronomists here who are
>>"struggling" with the taxonomy of Cassia/Chamaecrista/Senna.
>>Cassia hebecarpa (I think that's the correct spelling) is
>>being used in experiments dealing with nodule formation.  I
>>can not find this name in current floras.  Is this an older
>>name for C. merilandica?  Was it once a Chamaecrista?
>
>Senna hebecarpa (Fern.) Irwin & Barneby [Cassia hebecarpa Fern.]  is native
>to the ne. USA and was long confused with Senna marilandica (L.) Link
>[Cassia marilandica L.], which is found throughout much of the e. USA
>(Gleason & Cronquist, Man. Vasc. Pl. Northeast. US 273. 1991].  To the best
>of my knowledge, neither  has ever been placed in Chamaecrista.  Senna and
>Chamaecrista are both segregates of Cassia s. lat.  My impression is that
>many "leguminologists" are recognizing the segregates and a restricted
>Cassia, but I can't lay my hands on a good key to the three just now.
>However, I do note that Duane Isely (Mem. Torrey Bot. Club 25(2): 52-133
>accepts Cassia in the broad sense.
>...[snip additional discussion]
----------------------------------------------------------------------
Deborah Q. Lewis, Curator
Ada Hayden Herbarium (ISC)                           Ph. 515/294-9499
Department of Botany                                FAX: 515/294-1337
Iowa State University                      E-mail: dlewis at iastate.edu
Ames, IA  50011-1020  U.S.A.
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