Primitive-like metaphloem sieve elements in the aerial stem ofEquisetum hyemale

Summary Internodal metaphloem sieve elements located near the nodes of aerial stems ofEquisetum hyemale contain very oblique end walls. During maturation, the connections, or plasmodesmata, in these walls undergo little or no structural modification. By contrast, the endwall connections uniting the protoplasts of mature sieve elements elsewhere in the aerial stem ofE. hyemale are pores.This work as supported by U.S. National Science Foundation grant GB 31417 to R. F.Evert.