| Dicotyledon | Literature for Parthenium hysterophorus
Wagner et al., 1990, 1999; Lorence & Wagner, 2020. |
| Asteraceae -- The Sunflower Family | Bibliography |
| Parthenium hysterophorus | |
Common name(s): false ragweed, Santa Maria (Spanish) |
| General Information | ||
|---|---|---|
| Distribution | Native to tropical America.In the Hawaiian Islands, naturalized on Kaua`i, O`ahu, Moloka`i, Maui, Hawai`i. |
|
| Habit |
Taprooted, annual herb, 3‒10 dm tall; stem unbranched in proximal part, branched in distal part, longitudinally striate, hirsute. |
|
| Leaves |
Proximal leaves in a basal rosette, these deciduous at maturity and stem leaves remaining, short-petiolate; blade 3‒20 cm long, 2‒10 cm wide, bipinnatifid or pinnatifid. |
|
| Flowers |
Heads small, numerous in open panicles; rays white, 0.6 mm long; disk corollas cream colored, ca. 1 mm long; pappus of 2 petaloid scales inserted close to the corolla on either side, entire or notched. |
|
| Fruit |
Achenes black, obovate, 2‒2.5 mm long. |
|
| Chromosomes |
2n = 18, 34 36. |
|
| Contributor |
Nancy Khan |
