Strobilus

A strobilus (plural: strobili) is a structure present on many land plant species consisting of sporangia-bearing structures densely aggregated along a stem. Strobili are often called cones, but many botanists restrict the use of the term cone to the woody seed strobili of conifers. Strobili are characterized by a central axis (anatomically a stem) surrounded by spirally arranged or decussate structures that may be modified leaves or modified stems.

Leaves that bear sporangia are called sporophylls, while sporangia-bearing stems are called sporangiophores.

Lycophytes

Some members of both of the two modern classes of Lycopodiophyta (Lycopodiopsida and Isoetopsida) produce strobili. In all cases, the lateral organs of the strobilus are microphylls, bearing sporangia. In other lycophytes, ordinary foliage leaves can act as sporophylls, and there are no organized strobili.

Strobili of Lycopodium

Strobili of Lycopodium

Liquid-preserved strobili of Lycopodium, showing reniform sporangia through translucent sporophylls