A fungus disease, powdery mildew strikes under cool, humid conditions. Leaves will become covered with a whitish residue and may be curled and distorted. Powdery Mildew is not normally a serious affliction in that plants do not normally succumb to the disease. However, it is certainly unnattractive. A flower in which the center petals are folded into four quarters.
Genes are either dominant or recessive.
A dominant gene's characteristics will predominate when paired with a recessive gene. For a recessive gene to show, it must be paired with another recessive gene. Underside of the petal. Redout , Pierre Joseph. He is best remembered for his paintings of plants, especially roses and lilies.