|Fern gametophytes. I guess these might be Pneumatopteris pennigera, because that's what they were growing under.|
The little heart-shaped plants above are fern gametophytes. A familiar, big, leafy fern plant (it's called the sporophyte phase) produces spores in thousands of little structures—sporangia—underneath its leaves, and the spores don't grow into new leafy ferns, but into these little gametophytes. Gametophytes in turn produce gametes (eggs and sperms), and when a sperm fertilizes an egg a new sporophyte fern is born.
|Fern gametophyte, lower surface showing the notch and the tuft of rhizoids.|
|The small actively dividing cells of the notch form the growth point of the gametophyte.|
|Archegonia (circled). They're very hard to photograph with just a dissecting microscope and a hand held camera.|
Occasionally you can strike it lucky. This freshly-cut bank (below) was almost entirely covered by fern gametophytes, in many the eggs had been fertilized and young sporophytes were just emerging.
|Fern gametophytes, those on the right with young sporophytes emerging.|