MadSci Network: Botany

Re: Do all plant cells contain chloroplasts?

Date: Wed Mar 26 00:49:13 2003
Posted By: David Hershey, Faculty, Botany, NA
Area of science: Botany
ID: 1048556061.Bt

No, most chloroplasts are in the interior cells in leaves, termed the 
mesophyll, and the cells near the surface of green stems. Many leaf and stem 
epidermal cells lack chloroplasts. The epidermis is the outermost layer of 
cells on nonwoody plant parts. A pair of guard cells surround each leaf 
stomata. Guard cells usually have chloroplasts. Cells in xylem and phloem 
tissue also usually lack chloroplasts. Xylem and phloem provide structural 
support and internal transport of water, minerals and organic compounds in 
plant organs.

Most underground plant cells lack chloroplasts because chloroplasts require 
light for their development. Thus, underground organs such as roots, bulbs, 
tubers, corms and rhizomes would generally lack chloroplasts. However, 
underground cells often have other kinds of plastids, such as amyloplasts, 
which store starch. Undergound plant organs may develop some chloroplasts if 
exposed to light. 

Window leaf plants have fleshy leaves that are buried in the soil with just the 
top showing aboveground. The window leaves have many cells in the top center of 
the leaf that are transparent and let light reach the chloroplast-containing 
cells on the sides of the leaf. The transparent cells lack chloroplasts.

Parasitic plants, such as Indian pipe (Monotropa uniflora) and dodder, lack 
chlorophyll so have no chloroplasts. White or yellow tissue in variegated-leaf 
plants also lack chloroplasts. Albino plants also lack chlorophyll. Many 
nongreen flowers and fruits lack chloroplasts at maturity. 


Re: Chromoplasts and Leucoplasts - What are they?

Structure of a Plant Cell

Monotropa uniflora


Albino Corn Photo

Albino corn kept alive by feeding cut ends of leaves with sugar

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