POTGIETER, KURT* AND VICTOR A. ALBERT. Department of Plant Biology, University of Illinois, Urbana, IL, 61801 and The New York Botanical Garden, New York 10458-5126, USA. - Non-floral morphological correlates of the Apocynaceae s.s.-Periplocaceae-Asclepiadaceae transition (i.e., dispersal traits) mapped onto a trnL-F derived consensus tree.
Segregation of Apocynaceae s.l. into Apocynaceae s.s., Periplocaceae
and Asclepiadaceae has in past be based largely on the degree of
floral synorganization. Current morphological and molecular research,
ours based on 150 sequences of the trnL-F region, places the
Asclepiadaceae and Periplocaceae within the higher Apocynaceae s.s.
but resolution at this interface is not clearly defined. This lack of
resolution is mirrored by dispersal characteristics. Dispersal traits
have thus far have not received critical evaluation within a
phylogenetic context. The distinguishing seed coma of the
Asclepiadaceae/Periplocaceae is characteristic of the interface and
above and may derive from naked seeds of fleshy fruits (Carisseae
s.s.) and not from less derived circum-alate or -ciliate taxa
(Aspidosperma, Plumeria, Haplophyton). Critical
evaluation of dispersal characteristics appear to be phylogenetically
informative but certain characteristics (seed wing, ciliate coma)
require additional study. Furthermore, relationships between
invaginate placentae and arils (seed presentation traits) require
further investigation especially within the Tabernaemontaneae and
related tribes.
Key words: Apocynaceae, Asclepiadaceae, dispersal, Periplocaceae, relationships