Citrine (colour) than it is today and could be "reddish or brownish yellow; or orange; or amber (distinguished from yellow)". In today's English citrine as a colour is mostly confined to the contexts of (1) gemstones, including quartz, and (2) some animal and plant names. E.g., the citrine wagtail ("Motacilla citreola"), an Asian bird species with golden-yellow plumage, or the citrine warbler, citrine canary-flycatcher, citrine forktail, etc. Citrine (colour) Citrine is a colour, the most common reference for which is certain coloured varieties of quartz which are a medium deep shade of golden yellow. Citrine has been summarized at various times as
Basics of white flower colouration is a method to turn petunia flowers from white to transparent. The petunia flower is immersed into a flask of water, connected to a vacuum pump, after which the flower appeared colourless. The white colour is expressed by the air present in the vacuoles that absorb the light, without air the flower would lose the white colour. There is an increasing interest in flower colour, since some colorations are currently unavailable in plants. Ornamental companies create new flower colour by classical and mutation breeding and biotechnological approaches. For example white bracts in "Poinsettia" are obtained by high frequency irradiation. Basics