Fig. 5.

Most abundant patterns of organ combinations in position 4 and 5 of rosettes on a runner stolon node in U. dichotoma. After development of a first foliage leaf (L1) and two bladders (b2-b3), a rosette with next primordia (4–5) was built at the base of the leaf. The first organ of the rosette was either an anchor stolon (a4), a bladder (b4), a leaf (L4), or a runner stolon (R4). The sequence continues with the development of an anchor stolon (a5), a bladder (b5), a leaf (L5), or a runner stolon (R5). During further elongation, anchor stolons may build bladders; in this form, they are called ‘simple stolons’ (s). Numbers of organs/primordia represent the rank in the developmental sequence. Organs of ranks 4 and 5 may be inverted. Populations/sources (cf. Table 1 for abbreviations), in which the organ combinations of rank 4–5 were found, are shown in boxes in italic, whereas, e.g. ‘all -Oh, -La, etc.’ means that this combination was found in all populations except for the material from Lake Ohio (Oh), Lake Pearson (La), etc. Note that there may be more sources shown for a specific organ in rank 4 than sources for rank 4 and 5 in sum, since they may have contained nodes with unidentifiable organs after position 4