A highly specialized * sieve area , or collection of sieve areas, perforated by relatively large pores and usually located on the end walls of * sieve tube elements. A sieve plate composed of a single sieve area is called a simple sieve plate. A number of sieve areas may be arranged collectively to form a compound sieve plate, as in Nicotiana. The pores of a sieve plate, so named for its resemblance to a sieve, are lined with callose and penetrated by cytoplasmic strands. Compare perforation plate. |
