Chromolaena odorata L. R.M. king & H. Rob
Common Name : Siam weed
Family : Asteraceae

HABIT |
A HERBACEOUS TO WOODY PERENNIAL WITH A BUSHY HABIT WHICH FORMS A
VERY DENSE THICKET. |
STEMS |
UP TO 2 M TALL. TERETE AND
BECOME WOODY. TWIGS ARE SLIGHTLY STRIOLATE LONGITUDINALLY, PUBESCENT,
OPPOSITE-DECUSSATE. |
LEAVES |
SIMPLE, OPPOSITE-DECUSSATE AND WITHOUT STIPULES. THEY ARE
RHOMBOID-OVATE TO OVATE WITH AN ACUTE APEX AND A CUNEATE BASE. THE BLADES ARE
TRINERVED A FEW MILLIMETERS AFTER THE BASE, ROUGHLY CRENATE-SERRATE BEYOND
THEIR MAXIMUM BREADTH, SLIGHTLY PUBESCENT ABOVE AND PUBESCENT WITH NUMEROUS
SMALL YELLOW DOTS BELOW. |
FLOWERS |
CAPITULA ARE GROUPED IN 1, 3
OR 5 CONVEX TRICHOTOMIC CORYMBS, 5-10 CM IN DIAMETER, AT THE END OF THE
TWIGS. COLOUR RANGES FROM PALE-LILAC TO WHITE. |
FRUITS |
CYPSELA IS COMPOSED OF A 3-4-MM-LONG
FUSIFORM BLACKISH ACHENE, WITH FIVE BEIGE BARBELATE RIBS, OVERTOPPED BY A
PAPPUS OF ABOUT 30 BARBELATE BEIGE CAPILLARY BRISTLES WHICH ARE 4 -5 MM LONG. |