I call them spores but that's not right. Scientists would use the word sorus (pl. sori) which is a cluster of sporangia, which produce and contain spores in ferns and fungi. Spores of ferns are very small (perhaps 50 microns in diameter) so we don't see the spores per se - we see the sori (clusters). Sori form a yellowish or brownish mass on the edge or underside of a fertile frond. Different ferns have different sorus patterns, the shape, arrangement, and location of sori are used in the identification of fern taxa. It's also just darn fun to see all the different pattern - which I share here.
Sori may present themselves as a circular or linear form. The sori circles or lines may be arranged in neat rows, parallel or oblique to each other, or be random. Their location may be at the edge of the frond or set away on the frond blade (flat portion) usually on the bottom side. Sometimes the sori is wrapped in a protective layer which impacts its color and texture.
A sporophyte produces spores as part of it's reproductive cycle. Spores are life! Not going into the whole lifecycle discussion here, but just want to share some of the awesome patterns that sori make of various ferns. All the photos here were taken in my yard and at the Garfield Park Conservatory in Chicago which has an exceptional Fern Room. This display house has been maintained for over 100 years - the variety of ferns there is breath-taking! If you are in Chicago please check it out - and I'm happy to give you a tour as well :)
Please enjoy the photos below of a diversity of ferns and specifically the Sori patterns. It is fun that some of the latin names reference the sori patterns.
|Wart Fern - Australia|
|Climbing Bird's Nest Fern Sori - microsorum punctatum|
|Giant Fern - angiopteris angustifolia sori|
|Giant Chain Fern - Western North America|
|Green Wave Fern|