What is the Difference Between Waterhemp and Palmer Amaranth 

Both waterhemp and Palmer amaranth are aggressive, fast-growing weeds. Once they are established in a field, they are very hard to manage and remove.

What is the difference between waterhemp and palmer amaranth? Palmer amaranth has longer bracts, grows faster, and is more competitive than waterhemp.

Key Areas Covered

1. What is Waterhemp 
      – Definition, Features
2. What is Palmer Amaranth
      – Definition, Features
3. Similarities Between Waterhemp and Palmer Amaranth
      – Outline of Common Features
4. Difference Between Waterhemp and Palmer Amaranth
      – Comparison of Key Differences
5. FAQ: Waterhemp and Palmer Amaranth
      – Answers to Frequently Asked Questions

Key Terms 

Waterhemp, Palmer Amaranth, Amaranthus tuberculatus, Amaranthus palmeri, Weeds

What is Waterhemp

Waterhemp (Amaranthus tuberculatus) is a type of pigweed that’s native to North America. It’s a common problem for farmers, especially those growing crops like soybeans and corn in the Midwest. What makes waterhemp tricky to deal with is that it produces a lot of seeds and has developed resistance to many herbicides.

One way to tell waterhemp apart from other pigweeds, like red root pigweed, is by looking at the stem. Waterhemp’s stem is smooth and doesn’t have hairs, while red root pigweed has fuzzy hairs on its stem. The plant also has long, thin, and branched flower clusters, and its leaves are egg-shaped with long stems.

Waterhemp has male and female plants, which means it needs to cross-pollinate to produce seeds. This helps waterhemp adapt quickly to new environments. It usually sprouts between May and June, but it can continue to grow throughout the growing season.

Waterhemp is mostly found in crop fields, but it can also grow in wet areas like near ditches, on roadsides, or in places where the ground has been disturbed. In fields with irrigation, it can become a big problem, as it reduces the amount of crops that can grow. Herbicides often don’t work well against it, especially in crops like pulses, flax, canola, and sunflower, making it hard to control.

What is Palmer Amaranth

Palmer amaranth, or Palmer pigweed, is a fast-growing weed that has become a major problem in crops in the southern U.S. over the past few years. It’s originally from the Sonoran Desert and the lower Rio Grande Valley, but now it spreads easily into croplands, especially in hot climates.

This plant is tall and can grow quickly, often reaching 6 to 8 feet high and sometimes even more than 10 feet. Its stems and leaves are smooth without any hairs. The leaves are arranged in a pattern that makes the plant look a bit like a poinsettia when seen from above. They are elliptical or diamond-shaped with pointed tips and range in size from about 0.6 to 3 inches long.

Palmer amaranth has separate male and female plants. The female flowers have tiny, rigid spines that give the flower spikes a rough, bristly feel, while the male flowers are softer. These flower spikes can be up to 18 inches long.

Because it grows so quickly, thrives in hot and dry conditions, and has strong roots, Palmer amaranth competes aggressively with crops. Once it takes hold in a field, it can be extremely difficult to get rid of, making it a serious problem for farmers.

Similarities Between Waterhemp and Palmer Amaranth

1. Both waterhemp and Palmer amaranth are aggressive, fast-growing weeds.
2. They are difficult to control because of their resistance to herbicides.
3. Both have smooth, hairless stems.
4. They have separate male and female plants.
5. Both thrive in hot climates, which makes them more common in warmer regions.

Difference Between Waterhemp and Palmer Amaranth

Scientific Name

• Waterhemp is Amaranthus tuberculatus while Palmer Amaranth is Amaranthus palmeri.

Cotyledons

• Palmer amaranth has longer and narrower cotyledons compared to waterhemp.

True Leaves

• Palmer amaranth often has a small hair in the notch at the tip of its true leaves, but this is less common in waterhemp seedlings.

Bracts

• Palmer amaranth has longer bracts (up to ¼ inch) that extend far beyond the flower parts and become stiff and sharp. Waterhemp has shorter bracts, usually less than 3 mm, and they rarely extend beyond the flower parts.

Inflorescences

• Palmer amaranth typically has longer and thicker flower stalks than waterhemp.

Growth Rate

• Palmer amaranth grows faster and is more competitive than waterhemp and other pigweed species.

Conclusion 

Waterhemp and Palmer amaranth are fast-growing weeds that affect the crop yield in a field. The main difference between waterhemp and palmer amaranth is that palmer amaranth grows faster, has longer bracts, and is more competitive than waterhemp.

FAQ: Waterhemp and Palmer Amaranth

1. What is another name for Palmer Amaranth?

Palmer amaranth is also known as Palmer pigweed, tall amaranth, and Amaranthus palmeri.

2. How to identify waterhemp?

Waterhemp can be identified by several physical features. It has smooth, hairless stems that are usually green or reddish. The leaves are egg-shaped and arranged symmetrically around the stem, with long petioles (leaf stems). They typically measure between 2 to 6 inches long and 1 to 3 inches wide.

3. Is waterhemp invasive?

Yes, waterhemp is invasive. It spreads quickly and is hard to control. It also competes with crops, which causes problems for farmers.

4. What is the best amaranth for eating leaves?

The best amaranth for eating leaves is Amaranthus tricolor, often called Chinese spinach or Joseph’s coat. This type has tender, healthy leaves that you can eat raw in salads or cook in different dishes. Another good choice is Amaranthus viridis, known as green amaranth.

Reference: 

1. “Waterhemp (Amaranthus tuberculatus).” Montana State University.

2. “Palmer Amaranth (Amaranthus palmeri).” eOrganic.

Image Courtesy: 

1. “Amaranthus palmeri” by Pompilid (CC BY-SA 3.0) via Commons Wikimedia 

2. “Amaranthus tuberculatus stem (01)” (Public Domain) via Picryl