Tag Archives: giant ragweed

Giant Ragweed Ambrosia trifida

Every year I watch the giant ragweed start to grow. It lines the road. It surrounds the barn. It fills the barn lot and adjacent pasture. Its population gains every year.

The pollen spikes start growing. They get six to ten inches tall lined with green balls. When the green balls open, releasing pollen into the air, the boxes of tissues get set out around the house.

By mid September the spikes are only brown stalks. The pollen is gone for the year. Now the seeds scatter across the ground promising a new, bigger crop of giant ragweed next year.


Ambrosia trifida L.

July to September                                       N                                 Family: asteraceae

                                                                                                            Tribe: Heliantheae

giant ragweed male flowers

Male flowers

Flower: There are separate male and female flowers. The male flowers are in hanging bundles on a spire. One main and several auxiliary spires can come from the tips of each branch. The female flowers are tucked into swirls of bracts at the base of the spires. The flowers are wind pollinated.

giant ragweed female flowers

Two female flowers

Leaf: Opposite leaves are rough, green on the upper side, slightly paler on the under side and covered with very short hairs. Many of the leaves have three lobes but can have five or none. Main veins run out each lobe. The leaves have long petioles that can be winged. each leaf can reach twelve inches long and eight inches wide.

giant ragweed under leaf

Stem: The thick, ridged stem can reach 12 feet in height. It has branches. The stems are light green, rough to the touch, stiff, hollow and have lines of short hairs. The bases of tall stems thicken, become woody and can be three inches in diameter.

giant ragweed leaf

Root: The annual roots are fibrous around a taproot.

giant ragweed stem

Fruit: The seed is tan with an ovate base. the top has a main rounded spike surrounded by a ring of lower, rounded lobes.

giant ragweed fruit

Habitat: This plant prefers full sun, good soil and moisture. It is not particular and grows in a wide variety of places especially disturbed ground and pastures.

Edibility: Cattle, goats and deer eat giant ragweed. The seeds have a tough coat but can be eaten.


Giant Ragweed

Great Ragweed, Horseweed, Buffalo Weed

giant ragweed plant

Giant Ragweed is considered a noxious weed in some states. it does tend to form dense colonies once established in an area. It is the most abundant ragweed.

The plants are annuals and produce lots of seeds. These germinate in mid to late spring. The seedlings grow rapidly often in dense stands, many of which die from the competition.

Although, under ideal conditions, Giant Ragweed can to 12 feet with stalks three inches in diameter, tough enough to require a saw to cut them, many times the plants are cut or grazed or mowed off. The plants then put out new branches quickly reaching two to three feet and blooming. Even six inch plants will put up single spires.

As are other ragweeds, Giant Ragweed is wind pollinated. Each plant produces tremendous amounts of pollen. This is a major cause of hayfever in late summer.

Bees still visit Giant Ragweed male flowers to gather pollen. They may knock some pollen down on the female flowers, but do not visit them. They leave the pollen spikes heavily laden.

Archeologists find caches of Giant Ragweed seeds at various sites. The seeds are tough but do contain edible oils. Few birds can eat them due to the tough shells.

The Bee Army and My Goats

There must be several wild bee trees out in the woods because there are lots of honeybees around. Lately the bee army is humming up a storm.

Long ago there were two commercial bee hives here. The beekeeper died and the new one wasn’t interested in two hives. When the varola mites moved in, the bees moved out into the woods.

All summer my goats have been reluctant to go out because of horseflies. Having been bitten before I can’t blame them for wanting to avoid these pests.

goat herd at the gate

The gate is open. The pasture beckons. The goat herd stands under the hackberry tree waiting for the horseflies to attack.

I open the pasture gate and drive the herd out. they stand around outside the gate until the horseflies move in. Then they run out to pasture preferably in deep shade to discourage the flies.

A signature of the horseflies is their loud humming buzz as they zero in. It is a signal to the goats to crowd up trying to make sure the neighbor is the victim.

Now that buzz is everywhere.

In the milk room the bald-faced hornets are busy catching flies. Their buzz is very similar so the goats are jumpy making kung fu milking imperative.

Outside the bee army is humming over the giant ragweed. This is a wind pollinated plant with no nectar. Why are the bees moving in?

Adult bees and hornets drink nectar for food. This diet supplies lots of sugary energy but little protein. Their young require protein.

The bald-faced hornets solve this by catching flies to feed their young. Bees use pollen. Giant ragweed produces lots of pollen.

The goats ate the giant ragweed in their barn lot but, being a persistent weed, it regrouped and sent up new branches. Every new branch is tipped with tall towers lined with pollen pockets.

Walking through the ragweed patch leaves long yellow streaks on the jeans. Breathing deeply activates the hay fever.

bee army member on ragweed

Pollen sacs bulging a member of the bee army works her way up a giant ragweed tower stuffing more pollen in.

Every member of the bee army has bulging pollen baskets on their back legs. They land near the base of a tower and crawl upward stuffing more in until the basket is close to bursting.

The basket is unloaded at the hive. The bee returns with empty baskets to fill. The bees are welcome to all the pollen they can gather plus some.

Unfortunately for the goats the path out of the barn lot goes through the giant ragweed humming with bees. They think it is a horsefly army and refuse to go past.

Eventually hunger wins out. The goats go out.

Giant Ragweed Pollen Plague

Giant ragweed is an annual weed. If vegetables grew like it does, a family would need only a twenty foot square plot to feed themselves.

Of course I knew about ragweed that bane of hay fever sufferers. This coarse lacy-leafed plant would send up its towers filled with pollen released to blow on the wind.

The plant got four feet high. It got that tall only if the goats weren’t around.

Then I met giant ragweed only I didn’t know what it was. All I knew was this weed took over my potato patch towering over the poor stunted things at eight feet tall with stalks so thick I used a saw to cut them down!

giant ragweed plant

At up to eight feet tall Giant Ragweed towers over other plants along the road. It puts out branches making it four feet wide.

In the spring seedlings appear as a carpet over the ground. Each of the two cotyledons is a fat green water drop. They grow fast.

Any seedlings not pulled up are six inches tall in ten days. They are knee high in a month.

giant ragweed leaf

Giant ragweed leaves are shaped like dinosaur tracks with three lobes. The leaves can be over six inches wide and eight long.

August arrives. The giant ragweed has a thick stem and branches hung with large three lobed leaves.

Then the towers go up. I stock up on tissue and allergy pills. The towers open up letting loose their clouds of yellow pollen.

pollen flower of giant ragweed

The source of hay fever is in these towers going up from the top of the branches and plant. Each little section releases a cloud of pollen into the wind. each one can be two to four inches tall.

If these plants were only in the garden, control would be work but doable. Instead the plants are around the yard, along the road, in the garden. Anywhere plants can grow, there they are.

Anyone with goats knows what happens when the herd escapes. Fruit trees vanish. Gardens vanish or get trampled.

My herd came in from pasture the other day to find the big gate for the tractor open. No self respecting goat will turn down such an invitation. Mine are very respectful of themselves.

eaten giant ragweed plant

A few hard-to-see stalks and bits of leaf are left after my goats get through eating a giant ragweed plant.

I came out to find the herd had been out on the road and were now in the persimmon tree patch. Damage was minimal. Why?

Giant ragweed coming into bloom is a goat delicacy. The goats passed up all other browse in favor of stripping this weed, knocking it down to finish the job!

The gate is again securely latched. The goats are still enjoying giant ragweed. Only now I cut the stalks and carry them in to the hay trough. The bare stems go out to the brush pile in the morning.

I need to cut faster.

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