It sounds like you are describing the sepals. They look like that on some flowers. On other flowers, the sepal is colored the same or different than the petals.
Leaflike parts that cover and protect the flower bud
Liverwort
The Receptacle of a flower is the bottom of the flower. It holds everything together. reproductive parts of a plant. Receptacle is female
The Receptacle of a flower is the bottom of the flower. It holds everything together. reproductive parts of a plant. Receptacle is female
The Receptacle of a flower is the bottom of the flower. It holds everything together. reproductive parts of a plant. Receptacle is female
stem/ Edited answer: Pedicel and sepals
The sepals of a flower surround and protect the important parts such as the petals and reproductive organs. They are typically green and form the outermost layer of the flower before it blooms.
Each of the parts of the calyx of a flower, enclosing the petals and typically green and leaf like.
archegonium
The sepals are the leafy parts found near the bottom of a flower. When the flower is a bud, it is wrapped around it. Its purpose is to protect as it is growing and developing.
Flower (as the reproductive organ of a plant) doesn't have an antonym. As flowers are often the topmost parts, the nearest thing to an antonym would be the root, at the bottom.
Sepals protect the tender flower parts in the flower bud and being green in color perform photosynthesis also.