The true morels (Morchella spp.) are among the edible fungi most prized by mushroom hunters. As with other mushrooms, the familiar morel is merely the spore-producing "fruiting body" of a macrofungus which exists mostly undergound. A variety of morel species fruit briefly and sporadically each spring across the northern hemisphere and information on when and where to find them is often closely guarded by collectors. Much lore exists (some of it surely well founded) about the microhabitats and weather conditions associated with the appearance of morels. Morels grow throughout the northern hemisphere in regions with temperate or boreal forests, as well as in some Mediterranean and subtropical regions such as coastal California, the highlands of Central American, and the Middle East. Morels also occur in the southern hemisphere and although many of these are believed to be introduced, there are apparently endemic species as well in, for example, Australia and southern South America. Morels are harvested from the wild commercially in several parts of the world, including the United States, Turkey, China, and the Indian subcontinent, although some progress has been made toward commercial cultivation. (Pilz et al. 2007 and references therein). Pilz et al. (2007) provide an overview of the biology and ecology of morels.
In recent years, a number of researchers have used molecular genetic approaches to help resolve questions about species boundaries and species diversity within the genus Morchella (e.g., O'Donnell et al. 2011; Du et al. 2012). Du et al. (2012) recognized more than five dozen putative Morchella species. Building on this work, Kuo et al. (2012) formally described a number of new phylogenetic species from the U.S. and Canada and reviewed their current understanding of the taxonomy and nomenclature of Morchella in the U.S. and Canada (Kuo et al. 2012 includes a dichotomous identification key). Much taxonomic work remains to be done on this challenging group, but it appears that the old idea that Morchella includes just a handful of very widely distributed species is unlikely to persist in the face of much new data indicating high levels of genetic diversity within geographic regions.
Although they are widely considered to be choice edibles and large numbers are eaten each year without ill effect, morels reportedly can be toxic, especially when poorly cooked, producing both gastrointestinal and neurological symptoms. Researchers investigating reports of Morchella toxicity concluded that these cases were not simply the result of confusion with the superficially similar and poisonous False Morel (Gyromitra esculenta) or other causes, but noted the need for further study to confirm and better understand the phenomenon of morel poisoning. (Saviuc et al 2010)