I am unaware of any newer or better findings on hallucenogens than Dr. Shultes.
Under the heading "Old World Hallucinogens"
MARIHUANA, HASHEESH, or HEMP (species of the genus Cannabis), also called Kif, Bhang, or Charas, is one of the oldest cultivated plants. It is also one of the most widely spread weeds, having escaped cultivation, appearing as an adventitious plant everywhere, except in the polar regions and the wet, forested tropics.
Cannabis is the source of hemp fiber, an edible fruit, an industrial oil, a medicine, and a narcotic. Despite its great age and its economic importance, the plant is still poorly understood, characterized more by what we do not know about it than by what we know.
Cannabis is a rank, weedy annual that is extremely variable and may attain a height of 18 feet. Flourishing best in disturbed, nitrogen-rich soils near human habitations, it has been called a "camp follower," going with man into new areas.
It is normally dioecious--that is, the male and female parts are on different plants. The male or staminate plant is usually weaker than the female or pistillate plant. Pistillate flowers grow in the leaf axils. The intoxicating constituents are normally concentrated in a resin in the developing female flowers and adjacent leaves and stems.
http://www.erowid.org/library/books_online/golden_guide/g21-30.shtml
http://www.erowid.org/library/books_online/golden_guide/g11-20.shtml 
