The Collaborative International Dictionary of English v.0.48:

Alexanders \Al`ex*an"ders\, Alisanders \Al`i*san"ders\, n. [OE.
   alisaundre, OF. alissandere, fr. Alexander or Alexandria.]
   (Bot)
   A name given to two species of the genus Smyrnium, formerly
   cultivated and used as celery now is; -- called also horse
   parsely.
   [1913 Webster]