Three-dimensional reciprocity of floral morphs in wild flax (Linum suffruticosum): a new twist on heterostyly
Article first published online: 23 MAY 2006
Volume 171, Issue 3, pages 581–590, August 2006
How to Cite
Armbruster, W. S., Pérez-Barrales, R., Arroyo, J., Edwards, M. E. and Vargas, P. (2006), Three-dimensional reciprocity of floral morphs in wild flax (Linum suffruticosum): a new twist on heterostyly. New Phytologist, 171: 581–590. doi: 10.1111/j.1469-8137.2006.01749.x
- Issue published online: 23 MAY 2006
- Article first published online: 23 MAY 2006
- Received: 5 March 2006 Accepted: 6 March 2006
- disassortative pollen flow;
- floral development;
- Linum suffruticosum (wild flax);
- • Here, we studied the floral morphology and pollination of the distylous plant Linum suffruticosum (Linaceae) in southern Spain.
- • We observed a previously unreported form of distyly that involved twisting and bending of styles and stamens during floral development to achieve three-dimensional reciprocity of anthers and stigmas in the long-styled (pin) and short-styled (thrum) morphs. This developmental pattern causes pin pollen to be placed on the underside of pollinating Usia flies (Bombyliidae), and thrum pollen to be placed on the top of the thorax and abdomen. The pin stigmas contact the flies on the dorsum, apparently picking up predominantly thrum pollen, and the thrum stigmas contact the flies on the ventral surface, apparently picking up predominantly pin pollen.
- • This form of heterostyly would appear on morphological grounds to be far more efficient in dispersing pollen between compatible morphs than the typical pin–thrum system. If so, this plant fits Darwin's prediction of efficient pollen flow between heterostylous morphs more closely than anything Darwin himself reported.
- • Molecular phylogenetic analyses indicate that this form of heterostyly evolved in a lineage that already had typical heterostyly. The analyses also indicate that there have been several independent origins of heterostyly in Linum and at least one reversal to stylar monomorphism.