6.1.2: Selaginella

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Members of the genus Selaginella are heterosporous, meaning they produce two different types of spores.

Two Selaginella strobili with different looking sporangia — Figure \(\PageIndex{1}\): In the first image, there are liquid-preserved strobili of *Selaginella*, showing mega- and microsporangia through translucent sporophylls. The second image is a cross section through a strobilus. Notice that the spores contained within the sporangia are quite different in size. Labels are as follows: A) cone axis, B) microsporangium, C) microspores, D) microsporophyll, E) megasporangium, F) megaspore, G) megasporophyll. Photo on the left is by Curtis Clark, licensed as noted, CC BY-SA 2.5, via Wikimedia Commons. Photo on the right is by Curtis Clark, CC BY-SA 3.0, via Wikimedia Commons with labels added by Maria Morrow.

A long section through a Selaginella strobilus showing microspores and megaspores — Figure \(\PageIndex{1}\): In the first image, there are liquid-preserved strobili of *Selaginella*, showing mega- and microsporangia through translucent sporophylls. The second image is a cross section through a strobilus. Notice that the spores contained within the sporangia are quite different in size. Labels are as follows: A) cone axis, B) microsporangium, C) microspores, D) microsporophyll, E) megasporangium, F) megaspore, G) megasporophyll. Photo on the left is by Curtis Clark, licensed as noted, CC BY-SA 2.5, via Wikimedia Commons. Photo on the right is by Curtis Clark, CC BY-SA 3.0, via Wikimedia Commons with labels added by Maria Morrow.

Selaginella sporophyte spreading across the ground — Figure \(\PageIndex{2}\): Selaginella sporophytes have microphylls. These images show a *Selaginella* sporophyte spreading via dichotomous branching (first image) and the single, unbranched vein of vascular tissue present in each leaf (second image). Images by Sönke Bonde, CC0.