The Collaborative International Dictionary of English v.0.48:

Alexanders \Alexanders\ n.
   1. same as Alexander[wn1]; Smyrnium olusatrum.

   Syn: Alexander, black lovage, horse parsley, Smyrnium
        olusatrum
        [WordNet 1.5] Alexanders

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]

WordNet (r) 3.0 (2006):

Alexanders
    n 1: European herb somewhat resembling celery widely naturalized
         in Britain coastal regions and often cultivated as a
         potherb [syn: Alexander, Alexanders, black lovage,
         horse parsley, Smyrnium olusatrum]