Function of Xylem and Phloem in a Corn Plant

June 17, 2024

The corn plant continues to amaze and impress with the yields growers can produce despite being subjected to environmental challenges like drought, excess rain, excess heat, excess wind, and a host of other challenges. This is especially true in the west where drought stress occurs frequently and makes us wonder what is keeping the corn plant alive each year.

What keeps the corn plant fed with moisture and nutrients is a vascular bundle at the heart of the stem or stalk which consists of xylem and phloem. While corn is considered a grass, it is one of the few grass plants that does not have a hollow stem and consequently houses a substantial vascular bundle (Figure 1).

Vascular bundle of corn stalk.
Figure 1. Vascular bundle of corn stalk.

What are xylem and phloem with respect to the corn plant? Xylem is a conduit of dead, open ended cells that transport water and nutrients from root hairs up the plant. Capillary action within the plant, turgid pressure on the roots, and transpiration keep this system working. As moisture evaporates off leaf tissue, more water and nutrients flow up the plant.

The phloem serves as the distribution system for carbohydrates (sugars) produced during photosynthesis to where they are needed in the plant. Phloem differs from xylem in that it travels in many directions in the plant and feeds roots, leaves, and developing kernels.

The unique way xylem and phloem work in unison serves to feed the plant and move the growth and development process along. The process is even able to filter out larger particles like viruses and bacteria when the plant is healthy. Disruptions to the process are likely why stalk rot and other disease pressure occurs as the system gets challenged in times of severe environmental stress.

With this vascular system being an integral part of a corn plant’s survival, it needs to be a focus for management strategies with respect to precision nutrient management, irrigation management, fungicide use, and other high management strategies. Having a baseline of knowledge on how the system functions can be instrumental in helping to understand and implement corn management decisions.

Channel Agronomist
Jeremy (Jerry) Johnson