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Inflorescence morphology of some Australian 
Lasiopetaleae (Sterculiaceae) 
C. Bayer and K. Kubitzki 
Abstract 
Bayer, C. and Kubitzki, K. (Institut fiir AUgemeine Botanik und Herbarium der Universitat Hamburg, 
Ohnhorststr. 18, 22609 Hamburg, Germany) 1996. Inflorescence morphology of some Australian 
Lasiopetaleae (Sterculiaceae). Telopea 6(4): 721-728. The inflorescence morphology of 17 species 
out of five genera of the tribe Lasiopetaleae (Sterculiaceae) is investigated. The flowering 
shoots are sympodia composed of modules bearing several foliage leaves and a terminal 
inflorescence. In the inflorescences, metatopic displacements can be noted. The basic type, as 
represented by Keraudrenia, is identified as a cymoid with two lateral dichasia. In Thomasia, 
Hannafordia, Guichenotia and Lysiosepalwn, the inflorescences are cincinnoid. The three-bracteate 
epicalyx, which is found beneath each flower in these monochasial inflorescences, is 
homologous with a sterile bract and the two subtending bracts of the lateral cymes in 
Keraudrenia. The relatively primitive inflorescence structure of Keraudrenia links the 
predominently Australian tribe Lasiopetaleae with the pantropical tribe Byttnerieae. 
Introduction 
The Australian representatives of the tribe Lasiopetaleae (Sterculiaceae) exhibit 
different inflorescence types. In the taxonomic literature there are no indications 
how these forms are connected with each other and with the inflorescences of other 
members of the Sterculiaceae and Malvales. Due to the lack of precise characterisations 
it is not possible to use inflorescence characters for taxonomic comparisons, 
even less to polarize them. 
Only few taxonomists have attempted to take full advantage of characters provided by 
inflorescence morphology. This may be due to several reasons: the analysis of 
inflorescence structure is often complicated; a part of the relevant literature is written 
in languages other than English, and the different approaches and terminologies in use 
make the observations reported in the literature difficult to compare. Nevertheless, not 
only in comparative morphological studies, but also in taxonomic descriptions, a clear 
and precise terminology for the analysis of inflorescence characters should be used, as 
the one elaborated by Troll (1964, see also Weberling 1989) or Briggs & Johnson (1979). 
Indications in the morphological literature with respect to position and structure of 
the inflorescences of the Lasiopetaleae are confusing and contradictory. According 
to Gay (1821), the inflorescences are cymose, corymbose, racemose and sometimes 
leaf-opposed. Guichenotia tedifolia Gay is described as having an 'inflorescentia 
intrafoliacea'. According to Payer (1857), the basic inflorescence type of Lasiopetaliim 
is found in the 'dichasia' of L. 'corylifolium', in which each flower is thought of as 
being provided with two fertile bracts. Baillon (1870) denies the occurrence of leaf- 
opposed inflorescences in the Lasiopetaleae. Since the position of the inflorescence is 
said to be not exactly leaf-opposed, he assumes that the unusual arrangement can be 
explained by displacements, following his interpretation of the inflorescences of 
Byttneria (Sterculiaceae-Byttnerieae). According to Eichler (1878), the flowers are 
arranged in cymes or in aggregates composed of cymes, and Schumann (1895) 
describes them as terminal or leaf-opposed in some genera. 
