sym·po·di·um 
(sĭm-pōdē-əm)
(sĭm-pōdē-əm)n. pl. sym·po·di·a (-dē-ə)
An apparent axis that develops when growth occurs by means of lateral branches rather than continuing along the principal stem, often having a zigzag or irregular form. Also called pseudaxis.
[New Latin : SYN- + Greek podion, base (from pous, pod-, foot; see ped- in the Appendix of Indo-European roots).]
sym·podi·al (-dē-əl) adj.
sym·podi·al·ly adv.