English

Abstract

Bayer, C. and Kubitzki, K. (Institut fur Allgemeine Botanik und Herbarium der Universitiit 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, meta topic 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 Lysiosepalum, 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 sub tending 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. 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). Abstract Bayer, C. and Kubitzki, K. (Institut fur Allgemeine Botanik und Herbarium der Universitiit 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, meta topic 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 Lysiosepa/um, 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. 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 ledifolia Gay is described as having an 'inflorescentia intrafoliacea'. According to Payer (1857), the basic inflorescence type of Lasiopetalum 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.