The persistence of flower subtending bracts. These are modified leaves, usually differing in size, shape and colour from other leaves. Like color and smell flowers have many variations in their structure too.
According to Presence of Bracts:
- Bracteate Flower: Flowers, which have bract or bracts at its base is called bracteate flower, e.g. Crotalaria (Atoshi).
- Ebracteate Flower: Flowers, which have no bract at the base is called ebracteate flower. In Brassica flower there is no bract. A bract is a small leaf or leaf like organ in the axils of which arise flowers.
According to the position of Ovary:
- Hypogynous flower: A flower in which Calyx, Corolla and Androecium lies beneath the ovary is called hypogynous flower. Flowers of Datum, Hibiscus, Brassica, Solarium, and Chili etc. are hypogynous flowers.
- Epigynous flower: A flower in which Calyx, Corolla, and Androecium are placed above the ovary is called epigynous flower. Flowers of lau (Lagenaria), Kumra (Cucurbita), Jhinga (Luffa) etc are examples of epigynous flowers.
- Perigynous flower: A flower in which Calyx, Corolla and Androecium are placed around the ovary is called perigynous flower. The thalamus of perigynous flower is cup shaped and the ovary is placed in the concave center of the thalamus, e.g. Rose. ovary is placed in the concave center of the thalamus, e.g. Rose.