In my world, I have a type of plant with a two-stage life cycle. The first stage grows into a structure that functions like a greenhouse that allows in most of the Sun's light but insulates against temperature. It does this to support the second stage, an extremely delicate type of flower which can only grow in the exact conditions fostered by the first stage's greenhouse.
The first stage constructs the greenhouse by growing a ring of stalks that eventually meet at a point above the center of the ring; after meeting in the center the stalks [build? excrete? weave?] the greenhouse from meeting-point down to the ground. Edit: L.Dutch's answer made me realize size may be important here. I would like for these structures to be about a foot in diameter in the wild.
Is there any biological structure or nonbiological material that a plant could use as described to build greenhouse walls that permit a significant amount of light but shield against temperature fluctuations? This is a world that has some effects percieved by humans as "magic", and these effects are the reason a plant with such a tenuous life-cycle came into existence, but I would prefer the plant to operate on nonmagical principles aside from its magical start hence the science-based tag.
Thanks in advance for your advice!
Edit: @Alex P.'s comment pointed out that the original title sounded like I was asking for a list of materials. The actual intent behind the question is "is there at least one way for a plant to make this work", so I have updated the title to match.