XVI International Botanical Congess
Seven species and one variety are registred in Mexico: anagalloides, formosum, galinum, mutilum, pauciflorum, philonotis, silenoides and silenoides var. Mexicanum. A wide variation exist in the characteristics of cuticle, collenchyma and stomatic type, and seems to be due to the adaptation to enviromental conditions. However, there are populations in the central of Mexico, such as, H.galinum x H.pauciflorum and H.silenoides x H.philonotis with intermediate characteristics in anatomy foliar which indicates the possible hybrid formations in genus and area.