The verb G. lauthra- “to refresh; to revive (intr.)” appeared in the Gnomish Lexicon of the 1910s (GL/53). It was probably based on the early root ᴱ√LAWA having to do with plants; compare to ᴱQ. loista- “to refresh” derived from that root (QL/52).
Neo-Sindarin: For purposes of Neo-Sindarin I have adapted this verb as ᴺS. laeda- “to refresh, revive” based on the similar root √LAY; compare S. laew “fresh” < √LAY vs. G. laus “fresh” < ᴱ√LAWA.
A word in the Gnomish Lexicon of the 1910s glossed “a plant, herb” (GL/53), clearly based on the early root ᴱ√LAWA from the contemporaneous Qenya Lexicon with derivatives like ᴱQ. lauke “vegetable, plant (species)” (QL/52).