pro·to·stele \ˈprōd.əˌstēl, | ̷ ̷ ̷ ̷|stēlē\noun Etymology:prot- + stele : a stele that has the form of a solid rod or column with the phloem surrounding the xylem — called also monostele; compare siphonostele • pro·to·ste·lic\| ̷ ̷ ̷ ̷|stēlik\adjective