noun. (botany) tissue that conducts synthesized food substances (e.g., from leaves) to parts where needed; consists primarily of sieve tubes.
1. Noun, singular or mass Whitefly feed in plant phloem and remove sap. 2. Adjective Once phloem dies off, it becomes part of the outer bark. 3. Verb, base form The American elm and some of its cultivars are also susceptible to phloem necrosis, the bacterial disease wetwood, rots and insect damage.