Psilophyta-5

The fused Sporangia are borne on a short shoot. Two fused leaves are associated with the Synangium.

Each sporangium has 3 Lobes & Locules (chambers).

This indicates that separate Sporangia fused over time and created a "Synangium"
Syn means together like synthesize.

This hypothesis is supported by the observation that some "forms" have 3 Separate Sporangia. This trait has evolutionary importance as you will see later.

There is a branch trace which diverges from the Stele in the stem and ends at the base of each Sporangium of the Synangium.

Dehiscence
Each Locule splits longitudinally along a predetermined suture, and releases its Spores.
There are no Elaters!

Psilotum is Homosporous & each spore produces a Bisexual Gametophyte.

Immature Sporangium subtended by a Forked Leaf

Mature Sporangia becoming yellow.

Section through Psilotum Synangium with Mature Spores

Mature Spores have a Bean-like shape and are said to be Reniform. This is unusual & suggests that Psilotum may be related to a small group of Ferns which have similar spores and gametophytes.