Secondary module vegetative

T Vegetative secondary module (determinate) Pleurocarpous perichaetial module with... 

FIGURE 14.5 Architecture of pleurocarpous mosses characters 11 to 12 (perichaetial module origin and sub-perichaetial innovations). (A) Perichaetial modnles formed distaUy on primary modnles and on secondary modules, subperichaetial innovations absent (Pireella) (B) perichaetial modnles basal on primary modules, subperichaetial innovations present, fertile only (Pyrrhobryum) (C) perichaetial modules formed distaUy on primary module, subperichaetial innovations present, fertile only (Cryphaea) (D) perichaetial modnles formed nonspecificaUy on primary module, subperichaetial innovations present, both fertile and vegetative (Amblystegium). 

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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