Dictionary > Protophloem


noun, plural: protophloems
The first phloem to develop from the procambium
The phloem is a vascular tissue that is responsible for transporting photosynthates to different parts of a vascular plant through a process called translocation. The phloem may be primary or secondary. A primary phloem is the type of phloem that is produced by the procambium during the primary growth (vertical growth) whereas a secondary phloem is one that is produced by the vascular cambium during the secondary growth (lateral growth).
The primary phloem is comprised of the protophloem and the metaphloem. The protophloem is the first phloem that develops from the procambium. The protophloem develops first but is more sensitive to stretch or mechanical stress thus often does not develop fully compared to the metaphloem that attains full development when the plant reaches maturity, or when the internodes stopped from elongating.
Although they look similar, the protophloem can be seen near the exterior whereas the metaphloem is located adjacent to the metaxylem. The protophloem can be further differentiated from the metaphloem in terms of cellular components and morphology. In protophloem, the sieve elements are relatively thin-walled, narrow, elongated, and short-lived compared with those of the metaphloem. The companion cells may or may not be present in protophloem.
Word origin: Greek prôtos (“first”) + phloem
See also:

You will also like...

Physical growth
Physical Development in Humans

This tutorial elaborates on the physical development of humans, particularly from puberty to adulthood. Read this tutori..

An artistic depiction of a human embryo
Growth and Development of a Human Baby

Upon fertilization, a zygote forms and develops into an embryo. This tutorial elaborates on the growth and development f..

Cell structure
Cell Structure

A typical eukaryotic cell is comprised of cytoplasm with different organelles, such as nucleus, endoplasmic reticulum, G..

Ecosystem Succession
Ecosystem Succession

If the balance of nature is left untouched, landscapes can change dramatically over time. A previous ecosystem is supers..

Protein Synthesis

Part of the genetic information is devoted to the synthesis of proteins. mRNA, a type of RNA, is produced as a transcri..

Chemical effects on plant growth and development
Effect of Chemicals on Growth & Development in Organisms

Plants and animals need elements, such as nitrogen, phosphorus, potassium, and magnesium for proper growth and developme..