[ noun ] a barbed spine or bristle (often tufted on cacti) <noun.plant>
Glochidium \Glo*chid"i*um\, n.; pl. {Glochidia}. [NL., fr. Gr. ? the point of an arrow.] (Zo["o]l.) The larva or young of the mussel, formerly thought to be a parasite upon the parent's gills.