Botrychium virginianum, commonly known as the Rattlesnake Fern, is a type of fern that reproduces through spores. Here's why:

* Ferns are vascular plants but do not reproduce via flowers or seeds. They reproduce via spores, which are tiny, single-celled reproductive units.

Let's look at the options and why they are or aren't involved:

* Sporangia: These are involved. Sporangia are the structures that produce and hold the spores.

* Sori: These are involved. Sori are clusters of sporangia, often found on the underside of fern leaves.

* Flowers: These are NOT involved. Ferns do not produce flowers.

* Ovules: These are NOT involved. Ovules are structures that contain the female gamete (egg) in seed-producing plants. Ferns do not produce seeds.

Therefore, the structure not involved in the reproduction of Botrychium virginianum is flowers (and ovules).