In botany , the ray flower is one of the types of flowers that can be found in the chapter of certain families of plants, such as the Composite. The ligulate flowers are small, hermaphroditic, or sometimes functionally unisexual or sterile (in the latter case they are called neutral ). They are of zygomorphic symmetry , that is, of bilateral symmetry.
The calyx is null or the sepals are deeply modified, forming a papus or villain , from two to many scales, bristles or hairs, persistent, sometimes connate. The papus may be hairy, slightly bearded, or feathery.
The corolla is gamopetal, the five petals join each other forming a short tube and the blade is laterally prolonged in a ligule with 3 or 5 teeth. The tube is the part of the corolla closest to the insertion of the stamen filaments. The limbus is the most distal portion and comprises, towards the tube, the throat and distally, the lobes. Ligules usually have 5 teeth or lobes at their apex. [ 1 ]
The androecium usually has 5 stamens , which alternate with the corolla lobes. The filaments, separated from each other, are inserted in the corolla tube. The basifix anthers join each other, often with apical appendages or basal lobes, forming a tube around the style in which pollen is released, and the style then grows through this tube, pushing outward or taking up the pollen ( with variously developed hairs) and presenting it to floral visitors, after which the stigmas become receptive (i.e., with a plunger or brush pollination mechanism). The anthers show longitudinal and intrusive dehiscence. The grains ofpollen are usually tricolorated.
The gynoecium has 2 connate carpels , an inferior ovary, unilocular. They present a single anthropic ovule , with 1 integument and a thin megasporangium . The placentation is basal. The pistil presents a style that usually has a nectary at its apex . The style is divided distally into two branches ( stilar branches ) that have stigmatic papillae on their adaxial face arranged in two separate lines or in a single continuous band. [ 2 ]
- Frankel, R. & Galun, E. (1977). Pollination mechanisms, reproduction, and plant breeding. Monographs on Theoretical and Applied Genetics no. 2. Springer-Verlag. Berlin. ISBN 0-387-07934-3.
- Barkley, Theodore M .; Luc Brouillet, John L. Strother. "Asteraceae Martinov" . Flora of North America (English) . Retrieved November 4, 2008 .