Many lower vascular plants have single initial cell in apical meristem

Primary meristems (histogens) shown

Grape fern (Botrychium sp.) median longitudinal section of root tip showing a single large initial cell (somewhat shaped like a pyramid - "IC") that is characteristic of many lower vascular plants. Labeled are the first derivatives of the initial cell that form primary meristems (also designated as histogens). From these will develop the mature tissues designated.

1 = rootcap; 2 = protoderm (precursor of rhizodermis); 3 = ground meristem (precursor of cortex); 4 = procambium (precursor of vascular tissues)