Arisaema quinatum?

[George R Stilwell, Jr.]

Mike,

You may want to get a copy of Miklos Treiber's dissertation. I've
appended the Abstract.

Ray
<GRSJr at Juno.com>

ACCESSION NO.:  AAG8022516
TITLE:  BIOSYSTEMATICS OF THE ARISAEMA TRIPHYLLUM COMPLEX
AUTHOR:  TREIBER, MIKLOS
DEGREE:  PH.D.
YEAR:  1980
INSTITUTION:  THE UNIVERSITY OF NORTH CAROLINA AT CHAPEL HILL; 0153
SOURCE:  DAI, VOL. 41-04B, Page 1222, 00375 Pages
DESCRIPTORS:  BOTANY
ABSTRACT:  The genus Arisaema Mart. comprises over 200 species in
fifteen sections. The genus occurs in eastern Asia, the
center of distribution, Africa (Ethiopia), eastern North
America, and Central America (Mexico). Arisaema is
represented in eastern North America by two sections:
section Tortuosa Engl., has seven Asiatic and one eastern

North American and Mexican species, A. dracontium;
section
Pistillata Engl. includes eight eastern Asian species and
is
represented in eastern North America by the Arisaema
triphyllum complex.
The Arisaema triphyllum complex has long been the object
of
study by taxonomists. Apart from the controversy of the
nomenclatural application of the name A. triphyllum,
students of the North American Arisaema have also
differed
in their interpretation of the taxonomy and evolutionary
relationships of the taxa in this complex. The apparent
lack
of agreement and understanding of the taxonomy and the
evolutionary relationships of the complex stems from
polymorphism within, and intergradation among, the taxa
of
the complex. To increase our understanding and improve
our
interpretation of evolutionary relationships, thereby
strengthening the foundation upon which taxonomic
judgements
are made within this taxon, the present study was
undertaken
to investigate and describe the morphological variation,
ecological relations, cytology, and reproductive biology
of
the Arisaema triphyllum complex.
Morphologically, Arisaema triphyllum is comprised of
three
closely related taxa: subsp. triphyllum, subsp.
stewardsonii, and subsp. pusillum.
Ecologically, the subspecies of Arisaema triphyllum are
quite similar. The subspecies are sympatric over most of
the
species range and primarily occur in mesic to hydric
habitats. The developmental phenology of these taxa is
also
quite similar; thus, when sympatric, the plants of the
subspecies are in direct competition at each
developmental
phase.
Cytologically, the plants of the Arisaema triphyllum
complex
represent a polyploid series. Chromosome numbers of N =14
and 2N = 28 for plants of subsp. pusillum and
stewardsonii,
and N = 28 and 2N = 56 for subsp. triphyllum are
reported.
Measurements of stomatal guard cell length have been
shown
to be correlated with ploidal level.
Reproductively, the plants of the Arisaema triphyllum
complex are obligate outcrossers and do not produce seeds
in
the absence of fertilization with or without pollination.

Outcrossing is enforced by a self-incompatibility system
and
reinforced by herkogamy and dichogamy. Artificial
hybridization of plants of the tetraploid, subsp.
triphyllum, with the diploid taxa, subsp. pusillum and
stewardsonii was unsuccessful. Subspecies pusillum and
stewardsonii, however, were successfully hybridized,
although crossability was low. Pollination in all of the
subspecies is effected by fungus gnats of the family
Mycetophilidae. The efficiency of the pollination system
and
fecundity in plants of the A. triphyllum complex is
generally low compared to artificial pollination;
however,
seed germination frequencies are high. Plants of all of
the
subspecies can undergo sexual transformation; thus, an
individual plant can be dioecious or monoecious. Sexual
transformation is correlated with corm diameter and is
postulated to be caused by a switch in developmental
pathways early in flower morphogenesis. Plant sex ratios
in
natural populations of A. triphyllum are strongly male-
biased and are highly variable from population to
population, as well as from year to year. Plants of all
of
the subspecies also reproduce vegetatively by means of
rhizomes, perhaps the principal means of reproduction in
natural populations.
On the basis of morphological variation, ecological
relations, cytology, and reproductive biology, the
Arisaema
triphyllum complex is regarded as a natural phenetic and
probably phyletic group comprised of three closely
related
taxa: subsp. triphyllum, subsp. stewardsonii, and subsp.
pusillum.