Arisaema triphyllum

[George R Stilwell, Jr.]

Ladies & Gents,

With help form other AEGers, we have obtained a copy of
Treiber, M. 1980, Biosystematics of the Arisaema triphyllum  complex,
University of North Carolina, Chapel Hill. Originally, I had planned to
scan the document and add it to the list available from AEG. However,
it is 357 pages long, of which over 120 pages are devoted to data
listings, statistical tables, etc.
I simply isn't worth the effort to scan it. So, I'll attempt to abstract
the paper.

Basically, Treibers study shows agreement with Dr. Huttlestons taxonomic
division of A. triphyllum
into three subspecies:

ssp. triphyllum Huttleson
ssp. pusillum (Peck) Hutt.
ssp. stewardsonii (Britton) Hutt.

however, ssp. quinatum (Nutt.) Hutt. is not mentioned in the study.

Treiber shows that both ssp. pusillum and ssp. stewardsonii are diploid,
n = 14, 2n = 28
and will hybridize although crossability is low (aprox. 45% vs. 90% for
intraspecific pollenization),
while ssp. triphyllum is tetraploid, n = 28, 2n = 56,  and was not able
to cross this ssp. with
either of the other ssp. He notes that both Bickel and Huttleston have
reported natural hybrids
with 2n = 42 which were intermediate between ssp. triphyllum and ssp.
stewardsonii.

Treiber speculates that the A. triphyllum complex probably arose from one
ancestral population
which diverged resulting in two groups; one with a northern distribution
and one with a southern distribution. The northern group became ssp.
stewardsonii and the southern ssp. pusillum.
The two groups were sympatric over portions of their regions making
hybridization possible.
Hybridization of the two is believed to have produced the segmental
allotetraploid ssp. triphyllum.

Treiber does not make a key for A. triphyllum, but he does show a table
of nine characters which
distinguish the ssp. from one another. Interestingly, one of these is the
length of the stamatal guard
cells. The others are cataphyl length, flange width, spadix-club width,
spathe-hood color, spathe-tube
fluting, leaf vestiture, sterile spadix shape, and pollen grain diameter.

Literally, Treiber presents more data about the physical aspects of A.
triphyllum than I can assimilate.
There is also a lengthy bibliography which I will incorporate int our AEG
Bibliography.

However, I fail to find any conclusions that would extend the work of
Huttleston although
lots of corroboration is presented.  I am puzzled by the absence of any
discussion of
ssp. quinatum (Nutt.) Hutt., not to mention
f. attenuatum (Small) Engl., f. viride Engl., f. zebrinum (Sims) Seymore,
v. acuminatum Engl., and v. montanum Fern.

If there are questions about the paper that I have not addressed
adequately, please feel free
to E-mail them to me and I'll attempt to answer them. I apologize for
pooping-out on
reproducing the entire paper. It's always more satisfactory to read it
yourself, but there's
a limit to my energy and patience.

Ray
<GRSJr at Juno.com>

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