Final answer:
It is false that ferns can only produce one sex; they have a life cycle that includes a bisexual gametophyte phase capable of producing both male and female gametes.
Step-by-step explanation:
The statement that ferns are only able to produce one sex is False. Ferns have a complex life cycle known as alternation of generations, which includes both asexual and sexual phases. The sporophyte generation is the dominant phase in ferns, with the familiar leafy fronds we often recognize.
This sporophyte produces spores on the underside of its leaves in structures called sporangia. These spores give rise to a bisexual gametophyte phase, which is typically small and heart-shaped, and can produce both sperm and eggs. Sperm cells from the antheridia (male reproductive structure) are flagellated and swim to the egg in the archegonia (female reproductive structure) to complete fertilization.
Horsetails and ferns share this characteristic reproductive strategy. Thus, ferns are not limited to producing a single sex; they produce both male and female gametes in separate structures on the same gametophyte. An interesting observation is the case of the Appalachian bristle fern, known only from its gametophyte form, which has been reproducing asexually for millions of years.