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Abstract Detail


Developmental and Structural Section

Staedler, Yannick M. [1], Weston, Peter H. [2], Endress, Peter K. [3].

Structure and development of the gynoecium in Calycanthaceae (Laurales).

Calycanthaceae are sister to the remainder of Laurales, and the deepest split within the family occurred since at least 70 Mya between Idiospermum (Idiospermoideae) and the rest of the family (Calycanthoideae). Carpel number varies from 0-5 (Idiospermum), up to 35-43 per flower (Calycanthus occidentalis). In Calycanthaceae, as often in Laurales with a floral cup, a small carpel number is correlated with short and stout stigmas (Idiospermum), and a larger number with filiform stigmas (Calycanthoideae). Most carpels enclose two lateral ovules, which is unique in Laurales, in which carpels usually enclose only one, median ovule. Ovules are bitegmic, as in most other Laurales. Within Calycanthaceae, developmental studies of the gynoecium have only been carried out previously in Calycanthus floridus and fragmentarily in Chimonanthus praecox. We studied gynoecium development in Idiospermum and compared it with Calycanthus floridus, and also documented the morphology of anthetic gynoecia for all genera of Calycanthaceae. We found bifacial stigmas throughout the family; a compitum formed by the coherent stigmas was found in Idiospermum, Chimonanthus, and Sinocalycanthus. In Calycanthus floridus, coherence of the carpels to different degrees was observed, involving groups of 2-3 carpels or the innermost 6-8 carpels, but never all carpels of a flower. All fertile carpels have a short ascidiate and a long plicate zone; the inner carpels generally tend to have a more prominent ascidiate zone, as previously described in C. floridus by other authors. In Idiospermum, the inner carpels can be ascidiate for most of their length. In addition to the normal carpels with two ovules, carpels with only one lateral ovule occur in all taxa studied. In Calycanthoideae, uniovulate carpels seem not to be positioned at the beginning nor at the end of the ontogenetic spiral, but rather to form patches in the flower. In Idiospermum, carpels without ovules were also observed.


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1 - University of Zurich, Institute of Systematic Botany, Zollikerstrasse 107, Zurich, CH-8008, Switzerland
2 - Royal Botanic Gardens, Mrs Macquaries Road, Sydney, New South Wales, 2000, Australia
3 - University of Zurich, Institute of Systematic Botany, Zollikerstrasse 107, Zurich, ZH, 8008, Switzerland

Keywords:
gynoecium development
compitum
Calycanthaceae
Laurales
Basal angiosperms.

Presentation Type: Oral Paper:Papers for Sections
Session: CP26
Location: Boulevard C/Hilton
Date: Tuesday, July 10th, 2007
Time: 8:45 AM
Number: CP26004
Abstract ID:1121


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