(i) Morphine- poppy plant/Papaver somniferum,depressant.
(ii) cocaine - Erythroxylum coca,stimulates causes euphoria/hallucination.
(iii) Marijuana- cannabis sative,affects cardiovascular system of the body.
Detailed
(a) Morphine:
(i) source : Latex of unripe capsules of poppy plant (papaver somniferum)
(ii) Effect on human body : It has a sedative and analgesia and a calming effect. It is a depressant.it decreases blood pressure and depresses respiratory centre.
(b) Cocaine :
(i) Source - Erythroxylum coca
(ii) Effect on the human body: It is a powerful stimulant of CNS. Its higher doses causes hallucination and euphoria.
(c) Marijuana :
(i) Source: Cannabis Sativa
(ii) Effect on human body : It is hallucinogenic, affects the cardiovascular system of the body and may even cause psychosis.