Photo: Corey Leopold (Flickr)
Time once again for the Moment of Science Word of the Day. Ready? Today’s word is: Gametophyte.
Yes, Gametophyte. What, you may ask, is a Gametophyte? It’s the opposite of a Sporophyte. For A Moment of Science, I’m Don…
Excuse me. Hello? Oh, okay. Thanks.
The caller wants to know what a Sporophyte is. A sporophyte is one of the two stages a plant goes through in its life cycle. Human beings, as you probably know, reproduce sexually. That’s all we ever do. Let me rephrase that. The only way we human beings ever reproduce is sexually. Not so with plants. Plants reproduce both sexually and asexually.
This is possible because plants have a two-stage life cycle. Take moss as an example. In one stage, called the gametophyte stage, moss plants produce sex cells, called gametes. This is the old sperm and egg idea. The sperm meets the egg–how do you do–and fertilization occurs. However, what the egg grows into is not another gametophyte, but a sporophyte.
In the sporophyte stage, the moss produces spores–get it, sporophyte–which are released into the air or water. Away the spores go, carried by wind and waves. Spores are an asexual form of reproduction: no sperm and egg this time. Eventually the spores take root, or germinate, and grow into . . . guess what?
A new gametophyte, and the cycle starts again. One entire life cycle of a plant, from gametophyte to sporophyte to gametophyte, includes both a sexual and an asexual stage.