Relationship between the velvet-like texture of flower petals and light reflection from epidermal cell surfaces

Abstract

Texture such as velvet lustre contributes to the ornamental character of a flower, along with shape and colour. This study aims to clarify the relationship between the formation of the velvet lustre texture and the optical characteristics of light reflection from irradiated surfaces of velvety and non-velvety petals from 30 cultivars or varieties of ornamental plants representing 19 species from various families. The angle of incident light from the petal surface was set at 90°, 60° or 30°, then light reflection from the petal surfaces was observed using a digital microscope. The observed reflected light was composed of "exterior" reflected light (ERL), which is observed as sparkling white spots on the surface of the epidermal cells, and "interior" reflected light (IRL), which is reflected from inside the petal and determines the base colour of the petals. Velvety petals had two common characteristics: conical-papillate or domed epidermal cells and a dark colour. As the angle between the petal and the incident light decreased, the ERL spots took on a belt-like shape, and total ERL intensity became stronger. We concluded that the velvety texture is derived from characteristic ERL rays coupled with dark IRL. The long sloping surface of the epidermal cells contributes to the higher ERL intensity as petals are observed from more horizontal angles, causing characteristic reverse shading effects on velvety petals.

Visualization of micromorphology of petal epidermal features of waxy and velvety flowers in Phalaenopsis

“…In our study, the same texture could be found on both fuchsia and white colored petals. However, in one previous study [2] on selected ornamental flower materials included petals with a velvet luster texture and non-velvety texture showed that velvety petals had two common features, conical-papillate or dome shaped epidermal cells and dark colors. Moreover in our study, we only found waxy and soft velvety petals.…”

“…Samples were mounted on metal stubs, sputter-coated with gold, and adaxial surface of all the samples were examined under a Scanning Electron Microscopes (SEM) (XL-30-ESEM, FEI, Holland). The terminology of epidermis morphology suggested by previous researches was adopted in this study [2,14,19].…”

“…As they have petals with a hard texture, waxy flowers are able to be transported over longdistance and can be preserved for a longer time; they are becoming more and more popular on the flower market. However, studies [1,2] on the relationship between floral texture differences and petal epidermal cellular microtextures have provided insight for further studies of inheritance and defense mechanisms between different floral textures.…”

“…Floral texture is an important ornamental characteristic, and is also an important breeding trait of high ornamental and economic values. Previous studies regarding the floral textures of ornamental flowers found that different textures could generate distinct visual effects, such as metallic luster, velvet luster and diamond dust, which increase both the value of ornamental plants and the color diversity of flowers [1,2]. Different floral textures can increase the diversity of petal types and can be an important trait for breeding new cultivars.…”

Information on Flower Coloration and Pigmentation in Current Carnation Cultivars for Use in Future Flower-color Breeding

“…"Velvety lustre texture" is an important petal appearance characteristic in the flower market. The ornamental flowers exhibiting velvety texture generally have the petal conical papillary cells that accumulate a high level of anthocyanins (Zhang et al, 2015). 'Velvet Blue' (No.…”