Ragweeds are flowering plants in the genus Ambrosia in the aster family, Asteraceae. They are distributed in the tropical and subtropical parts of the Americas, especially AMERICA, where the origin and center of diversity of the genus are in the southwestern USA and northwestern Mexico. Several species have already been introduced to the Old World and several have naturalized and also have become invasive species. Ragweed species are expected to keep spreading across Europe soon in response to ongoing climate change. Learn about thc vape juice discreet shipping usa
Other common names include bursages and burrobrushes. The genus name is from the Greek ambrosia, meaning “food or drink of immortality”.
Ragweed pollen is notorious for triggering allergic reactions in humans, especially allergic rhinitis. Up to half of most cases of pollen-related allergic rhinitis in THE UNITED STATES are because of ragweeds.
The most widespread species of the genus in america is Ambrosia artemisiifolia.
Ragweeds are total annual and perennial herbs and shrubs. Species may grow just a few centimeters tall or well exceed four meters high. The stems are erect, decumbent or prostrate, and many grow from rhizomes. The leaves could possibly be arranged alternately, oppositely, or both. The leaf blades can be found in many shapes, sometimes divided pinnately or palmately into lobes. The edges are smooth or toothed. Some are hairy, & most are glandular.
Ragweeds are monoecious, most making inflorescences which contain both staminate and pistillate flowers. Inflorescences have a tendency to be in the sort of a spike or raceme made up mostly of staminate flowers with some pistillate clusters around underneath. Staminate flower heads have stamens surrounded by whitish or purplish florets. Pistillate flower heads have fruit-yielding ovules surrounded by many phyllaries and fewer, smaller florets. The pistillate flowers are wind pollinated, and the fruits develop. They are burs, sometimes adorned with knobs, wings, or spines.
Many Ambrosia species occur in desert and semi-desert areas, and many are ruderal species that grow in disturbed habitat types.
Ragweed pollen is a common allergen. An individual plant may produce in regards to a billion grains of pollen per season, and the pollen is transported on the wind. It causes about half 50 % of all cases of pollen-associated allergic rhinitis in North America, where ragweeds are most abundant and diverse. Common culprits are normal ragweed (A. artemisiifolia) and great ragweed (A. trifida).
Concentration of ragweed pollen-in the lack of significant rainfall, which removes pollen from the air-is the least expensive in the early morning hours (6:00 AM), when emissions starts, and pollen concentration peaks at midday. Ragweed pollen can remain airborne for days and travel great distances, affecting persons numerous miles away. It might even be carried 300 to 400 miles (640 km) out to sea. Ragweeds native to the Americas have been completely introduced to Europe starting in the nineteenth century and especially during World War I, and also have spread rapidly there for the reason that 1950s. Eastern Europe, particularly Hungary, has been badly damaged by ragweed for the reason that early 1990s, when the dismantling of Communist collective agriculture led to large-scale abandonment of agricultural land, and new building projects also led to disturbed, un-landscaped acreage.