<Li> Osmia graciliflorum (DC .) Sch. Bip . </Li> <Li> Osmia odorata (L .) Sch. Bip . </Li> <P> Chromolaena odorata is a tropical and subtropical species of flowering shrub in the sunflower family . It is native to the Americas, from Florida and Texas in the United States south through Mexico and the Caribbean to South America . It has been introduced to tropical Asia, west Africa, and parts of Australia . Common names include Siam weed, Christmas bush, devil weed, camphor grass, common floss flower, communist green and triffid . </P> <P> Chromolaena odorata is a rapidly growing perennial herb . It is a multi-stemmed shrub to 2.5 m (100 inches) tall in open areas . It has soft stems but the base of the shrub is woody . In shady areas it becomes etiolated and behaves as a creeper, growing on other vegetation . It can then become up to 10 m (33 feet) tall . The plant is hairy and glandular and the leaves give off a pungent, aromatic odour when crushed . The leaves are opposite, triangular to elliptical with serrated edges . Leaves are 4--10 cm long by 1--5 cm wide (up to 4 x 2 inches). Leaf petioles are 1--4 cm long . The white to pale pink tubular flowers are in panicles of 10 to 35 flowers that form at the ends of branches . The seeds are achenes and are somewhat hairy . They are mostly spread by the wind, but can also cling to fur, clothes and machinery, enabling long distance dispersal . Seed production is about 80000 to 90000 per plant . Seeds need light to germinate . The plant can regenerate from the roots . In favorable conditions the plant can grow more than 3 cm per day . </P>

What is the botanical name of siam weed