Rhaphides

from The Collaborative International Dictionary of English v.0.48

Rhaphides \Rhaph"i*des\, n. pl. [NL., fr. Gr. ???, ???, a
   needle, F. raphides.] (Bot.)
   Minute transparent, often needle-shaped, crystals found in
   the tissues of plants. [Written also {raphides}.]
   [1913 Webster]