Ambrosia chamissonis
Encyclopedia
Ambrosia chamissonis is a species of ragweed
known by the common names Silver Burr Ragweed, Silver Beachweed and (Silver) Beach Bur(r).
It is known from most of the coastline of western North America from Alaska
to Baja California
, where it is a resident of beaches and other sandy coastal habitat. This is a large, sprawling perennial herb exceeding three meters in maximum width. The stems are roughly or softly hairy and longitudinally ridged. The plentiful leaves are a few centimeters long, woolly and silver-green, and variable in shape. The plant is monoecious
, with male and female flowers on each individual. Staminate
(male) flower heads
containing many pale colored florets occur at the tip of the inflorescence
, with pistillate
(female) flower heads clustered below them. Each pistillate head contains a single tiny flower which develops into a fruit. The fruit is a brown bur
up to a centimeter wide covered in sharp spines.
Ragweed
Ragweeds are flowering plants in the genus Ambrosia in the sunflower family Asteraceae. Common names include bitterweeds and bloodweeds....
known by the common names Silver Burr Ragweed, Silver Beachweed and (Silver) Beach Bur(r).
It is known from most of the coastline of western North America from Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
to Baja California
Baja California
Baja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North...
, where it is a resident of beaches and other sandy coastal habitat. This is a large, sprawling perennial herb exceeding three meters in maximum width. The stems are roughly or softly hairy and longitudinally ridged. The plentiful leaves are a few centimeters long, woolly and silver-green, and variable in shape. The plant is monoecious
Plant sexuality
Plant sexuality covers the wide variety of sexual reproduction systems found across the plant kingdom. This article describes morphological aspects of sexual reproduction of plants....
, with male and female flowers on each individual. Staminate
Stamen
The stamen is the pollen producing reproductive organ of a flower...
(male) flower heads
Head (botany)
The capitulum is considered the most derived form of inflorescence. Flower heads found outside Asteraceae show lesser degrees of specialization....
containing many pale colored florets occur at the tip of the inflorescence
Inflorescence
An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...
, with pistillate
Gynoecium
Gynoecium is most commonly used as a collective term for all carpels in a flower. A carpel is the ovule and seed producing reproductive organ in flowering plants. Carpels are derived from ovule-bearing leaves which evolved to form a closed structure containing the ovules...
(female) flower heads clustered below them. Each pistillate head contains a single tiny flower which develops into a fruit. The fruit is a brown bur
Burr (fruit)
A bur is a seed or dry fruit in which the seeds bear hooks or teeth which attach themselves to fur or clothing of passing animals or people. The hooks or teeth can be irritants and very hard to get off of clothing, such as wool or cotton...
up to a centimeter wide covered in sharp spines.