1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

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 Cardiolonchium .

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 used here.

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.

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