What Is a Sporophyll? Leaves That Bear Spores
A sporophyll is a leaf that carries spore cases. University of Wisconsin Botany says spores form in sporangia, which are borne on leaves termed sporophylls.
The short answer
A sporophyll is a leaf that bears sporangia, the cases where spores form. UW Botany says a cluster of sporophylls at the tip of a shoot is called a strobilus. Club mosses use them. Iowa State says ferns carry spores on frond undersides or on special fertile fronds that do the same job.
How do sporophylls work in club mosses?
UW Botany says lycophytes bear spores in sporangia on sporophylls. In club mosses these cluster at a shoot tip as a strobilus. Club mosses make one type of spore, which UW Botany says leads to bisexual gametophytes, a condition called homospory. Spike mosses make two spore sizes. Megaspores form in megasporangia on megasporophylls and microspores in microsporangia.
| Option | What it does | Source |
|---|---|---|
| Sporophyll | Bears sporangia | Introduction to vascular plants: the lycophytes (Botany 130) |
| Strobilus | Cluster at shoot tip | Introduction to vascular plants: the lycophytes (Botany 130) |
| Megasporophyll | Bears big spores | Introduction to vascular plants: the lycophytes (Botany 130) |
Do ferns have sporophylls?
Iowa State says ferns form spores in clusters known as sori. They sit on frond undersides or on special fertile fronds. NC State says cinnamon fern has separate stiff fertile fronds in early spring that quickly turn cinnamon brown. Its sterile fronds reach 2 to 4 feet plus stay green through summer.
Sori: frond undersides. Fertile frond: cinnamon fern. Sterile frond: 2 to 4 feet.
What happens to spores after release?
Iowa State says mature sori turn dark brown or black then release spores. A spore grows into a tiny heart shaped prothallus. USDA Forest Service says the plant we see as a fern is the sporophyte generation, which generally releases spores in summer. Spores need a moist sheltered spot to grow.
Dark sori: ready to release. Summer: spore release. Moist spot: spore grows.
Troubleshooting
Cone tip on a club moss? UW Botany says that is a strobilus of sporophylls.
Brown frond in spring? NC State says cinnamon fern fertile fronds turn cinnamon brown.
No spores on a frond? It may be a sterile frond per Iowa State.
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Sources
- Introduction to vascular plants: the lycophytes (Botany 130), University of Wisconsin Botany
- Osmundastrum cinnamomeum (cinnamon fern), NC State Extension Gardener Plant Toolbox
- Growing ferns from spores, Iowa State University Extension, Yard and Garden
- Fern reproduction, USDA Forest Service
FAQ
Is every fern frond a sporophyll?
No. Iowa State says spores form on frond undersides or on specialized fertile fronds.
What is a fertile frond?
NC State says cinnamon fern bears separate stiff spore bearing fronds in early spring.
Do club mosses have sporophylls?
Yes. UW Botany says club moss sporophylls cluster at the shoot tip as a strobilus.
How do spores leave a sporophyll?
Iowa State says mature sori darken then release microscopic spores.
What is a megasporophyll?
UW Botany says it is a leaf bearing megasporangia, which hold the larger spores.
