Old Testament Hebrew Lexical Dictionary
Strong's #5636 - סִרְפָּד
1) an unidentified desert plant
1a) meaning doubtful; perhaps brier, nettle
Jeff Brenner, Ancient Hebrew Research Center Used by permission of the author.
סִרְפָּד m. Isaiah 55:13 a plant growing in the desert. LXX. Theod. Aqu. κόνυζα; Vulg. urtica. Jo. Simonis (even in his first edition) compared it with Syr. ܣܶܦܕܐܳ white mustard; and this has been again brought forward by Ewald, Hebr. Gram.; but this latter word is from the Pers. سييد, اسييد white; and it cannot seem to be contracted from the word before us.
the Third Week after Easter