|
|
||||||||
2 Department of Biology (Ecology, Evolution, and Marine Biology), University of California, Santa Barbara, California 93106 USA; Department of Biology, Louisiana State University, Baton Rouge, Louisiana 70803 USA; and 4 Department of Biology, Saint Louis University, Saint Louis, Missouri 63103-2010 USA
Floral development was compared with scanning electron microscopy in 12 Australian species of Hibbertia representing most of its morphological variation, and in the related Adrastaea (Dilleniaceae). Calyx and corolla arise in quincuncial helices in radially symmetrical species, while the petals initiate unidirectionally from one side in zygomorphic species. Stamen number (3200+) proliferates by centrifugal addition of individual primordia or by innovations of common primordia and ring meristems. Common primordia arise in single-stamen positions alternately with petals, and each produces one to several stamens centrifugally that remain attached to a shared base and form a stamen fascicle. A ring meristem in Adrastaea initiates a whorl of five stamens, alternate with the first stamens but outside their whorl. In radially symmetrical species of Hibbertia, a first ring of stamens is supplemented centrifugally by additional stamens on a meristem ring. The first stamens in zygomorphic species of Hibbertia initiate as a terminal ridge on the floral apex, with subsequent stamens added centrifugally on one side and two carpels initiated on the opposite side. The carpels arise as a simultaneous ring in radially symmetrical flowers, or as a simultaneous pair in zygomorphic species. Staminodial presence is viewed as of minor significance. Four pollinator syndromes are proposed for Hibbertia, related to differing floral architecture.
Key Words: Adrastaea androecium centrifugal Dilleniaceae flower Hibbertia stamen fascicles zygomorphy
This article has been cited by other articles:
![]() |
L. P. Ronse De Craene Are Petals Sterile Stamens or Bracts? The Origin and Evolution of Petals in the Core Eudicots Ann. Bot., September 1, 2007; 100(3): 621 - 630. [Abstract] [Full Text] [PDF] |
||||
![]() |
L. P. RONSE DE CRAENE Floral Development of Berberidopsis corallina: a Crucial Link in the Evolution of Flowers in the Core Eudicots Ann. Bot., November 1, 2004; 94(5): 741 - 751. [Abstract] [Full Text] [PDF] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |