All the traits you have mentioned are adaptations by species to the physical environement they live in. Natural selection favors members of species that have some special quality that enables them to deal with the rigors placed upon them within that environment. A good example is the snow fox, whose fur is snow white in winter time, when snow is on the ground, but changes to a more natural fox-like fur color during the summer season. Flowers are more genetically disposed towards producing specific flower colors depending on the pH of the soil. Using the cabbage juice pH scale, acidic soils produce purple to pink flowers, while more basic soils produce green to yellow colors. As for humans, think about the environment of the African continent around the equator, primarily, compared to the harsh, frozen tundra of the Alaskan north. The people in the African setting are slimmer, taller, capable of dealing with the heat of their surroundings, while the native Inuit peoples of the north are shorter, and have more body fat to help them stay warm. Environmental factors have been very effective at enforcing requirements on species for survival.
For reptiles, the environmental climate changes can affect whether or not the reptile is a female or a male. For example, crocodile embryos do not have sex determining chromosomes. Males are produces at higher temperatures and females are produced at lower temperatures.
For humans, height and weight is determined genetically and environmentally. For the most part genetics plays a role in how tall or short an individual is. If both of your parents are short, their is a high probability that you are going to be short. They have found that there is some correlation between a mother's age and height of her children. If the mother is older in age, there will be an increase in the height of the research. There isn't must support for this theory. There has also been cases where people who live in hot areas are very tall. The height increase surface area so that the body can lose heat quickly. This is a great trait to have in warm weather.
For flowers, I have only heard of hydrangeas changing their color in terms of pH. Mostly genetic factor control color in flowers. For hydrangeas, they turn blue in acid soil and pink in basic soil. The color change is caused by adding ammonium or any alkali metals to the soil.
For seasonal fur colors, correspond to the weather and climate. For example, arctic foxes change their color in the winter and the summer. Their fur color is lighter in the winter to camouflage with the snow. Also they change their fur color to a dark grey in the summer time to camouflage with the trees and the ground.