Abstract

VAZQUEZ-SANCHEZ, Monserrat; TERRAZAS, Teresa  and  ARIAS, Salvador. Habit and growth form in the tribe Cacteae (Cactaceae, Cactoideae). Bot. sci [online]. 2012, vol.90, n.2, pp.97-108. ISSN 2007-4476.

The terms 'growth form' and 'habit' are often used as synonyms. However, their assignment to different species is problematic because of the morphological diversity occurring in some taxonomic groups, as is the case in Cactaceae, particularly in the tribe Cacteae of the Cactoideae subfamily. Stem morphology was studied in 102 species (26 genera) of Cacteae in order to identify the habit and to recognize how many growth forms occur in the tribe, as well to make a distinction between the concepts of habit and growth form in Cactaceae, and to discuss the differences between them and the concepts of life form and plant architecture. Based on observations and measurements for 102 species of Cacteae, four growth forms (cylindrical, columnar, globose, and globose-depressed) were recognized. Neither the habit 'tree' or 'herb' can be assigned to any member of Cacteae based on their size or longevity. Twelve percent of the studied species of this tribe have basitonic branching (shrubs) as for Acharagma roseana,Ferocactus pilosus and Thelocactus bicolor. In order to avoid confusion, we suggest using only the term 'growth form' when referring to the various stem forms in the Cacteae tribe.

Keywords : columnar; cylindric; globose; life form; plant architecture; shrub.