F. Piesschaert et al., DIALYPETALANTHUS FUSCESCENS KUHLM (DIALYPETALANTHACEAE) - THE PROBLEMATIC TAXONOMIC POSITION OF AN AMAZONIAN ENDEMIC, Annals of the Missouri Botanical Garden, 84(2), 1997, pp. 201-223
The neotropical rainforest tree Dialypetalanthus fuscescens Kuhlm. is
the only species of the Dialypetalanthaceae. In-depth morphological an
d anatomical documentation is presented, including newly recorded feat
ures such as indeterminate inflorescences, anthers with calcium oxalat
e packages, silica bodies in the wood, U-shaped placentas and dendriti
c hairs, and corrections of erroneous literature observations, e.g., o
n supposed stipular dimorphism. The genus is heterobathmic, combining
advanced gynoecial characters with such primitive features as free pet
als, dimery, stipules, and (here postulated) cantharophily. In the pas
t, Dialypetalanthus was most frequently suggested to be related to Myr
tales or Gentianales. However, because of the lack of bicollateral vas
cular bundles, presence of well-developed stipules, paracytic stomata,
obvious endosperm and unitegmic ovules, seed-coat structure, and gyno
ecial origin of the disk, a close relationship with the Myrtales is un
likely. An affinity with the Gentianales, the Rubiaceae in particular,
is accepted instead. It is concluded that ontogenetic and micro- and
macromolecular data are much needed for a further elucidation of the r
elationships of Dialypetalanthus .