Chromosome counts for the section are few with both 2N = 30 and 60 being reported.
Aneuploids have been counted in A. signatum C. Koch & Matthieu with 2N=34 and 30 + If.
Little is known about crossability, however A. subsignatum Schott has been hybridized
with A. cerrocampanense Croat, A. crystallinum Linden & André and A. regale Linden of section
XVII. SCHIZOPLACIUM Schott (Fig. 43-45)
Schott (1860) included all palmately lobed (but not dissected to the base) species in his
section Schizoplacium and all species which had leaves palmately lobed to the base into his
section Dactylophyllium . Engler (1905) placed all species with palmately divided leaves into
section Schizoplacium but created two divisions within the section to accommodate these. Each
of these divisions is called a "series' Schott's treatment is considered more natural and will be
Section Schizoplacium, as treated by Schott is probably a very natural one containing
only three species (considering current synonomy). Even considering plants described since
Schott's time there are only seven species in the section. These include A. angustisectum Engl.,
A. expansum Gleason, A. longissimum Pittier (Fig. 43), A. palmatum (L.) G. Don, A. pedatum
Kunth, A. pedatoradiatum Schott and A. podophyllum (Cham. & Schlecht.) Kunth (Fig. 44 & 45).
Only three chromosome counts have been reported for this unusual section and the counts
of 2N = 30, 2N = 39 and N = 15 indicate that more work needs to be done with this group to
understand its cytological relationship with other sections. Both A. pedatoradiatum Schott and
A. podophyllum Kunth were placed in section Dactylophyllium (following Engler's system of
classification) by Sheffer & Croat (1983) but as previously stated they are best placed in
section Schizoplacium . No crossability data is available.
XVIII. DACTYLOPHYLLIUM Schott (Fig. 46-48)
The section Dactylophyllium consists of all species which are palmately lobed to the base
(i.e., with free segments). The number of segments may be 3, 5 7, 9 or more but always the
number is an odd one. The age of the blade is often reflected by the number of leaflets present.
Some species never have more than three segments. These include A. thrinax Madison,
A. arisaemoides Madison (Fig. 46), A. cutucuense Madison, S. trisectum Sodiro and
A. triphyllium Brongn. ex Schott (Fig. 47).
Examples of species with five or more leaf-segments include A. brevipedunculatum
Madison, A. buchtienii Krause, A. clavigerum Poepp., A. croatii Madison (Fig. 48), A. eminens
Schott, A. kunthii Poepp., A. pentaphyllum (Aubl.) G. Don, A. polydactylum Madison and
A. polyschistum Schultes & ldrobo.
Chromosome counts in this section have been primarily 2N = 30 though a number of
counts of 2N = 60 indicate a certain amount of polyploidy as well. Aberrant counts of 2N-60 +
4 fragments and 2N-60 + IB chromosome indicate a need for more cytological work with the
group. Certainly the group appears superficially to have no relationship to section
Cardiolonchium (another group where B chromosomes have been reported). Very little is