Primary module indeterminate

By producing determinate or indeterminate branches at the level of primary module sympodial branching is reiterative. It is full reiteration rather than partial reiteration. The new primary module produced in this way has the potential to produce all the subsidiary branches and structures of lower hierarchical levels characteristic of the species (i.e., the components of the architectural unit). Sympodial branching then produces new architectural units. Less commonly sympodial branching may also produce shoots at other hierarchical levels, but the most important level for moss structure is that of the primary module. 

Other features that can be used to distinguish between primary and secondary modules are the relative diameter of the axis, the point on the subtending module at which the module originates, and whether or not it appears to be determinate or indeterminate. However, in some cases there may be no obvious difference between modules, and no objective alterion that can be used, in which case all vegetative modules have to be regarded as primary. 

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