Evolutionary aspects of life forms in angiosperm families

The distribution patterns of life forms among extant families, subclasses and classes are described with the aim of detecting evolutionary trends. The explosive diversification of angiosperms constrains the possibilities for detecting such trends. Moreover, the extant groups of seed plants are only a small sample from the historical diversity. Nevertheless, we could distinguish between common, scattered, clustered, and rare distribution patterns among groups of families in subclasses. The rare category may represent specialized life forms, including epiphytes, carnivorous plants, (hemi)parasites, saprophytes, succulents, xerophytes, halophytes, aquatics and marsh plants. Geophytes and lianas have a more scattered distribution pattern among the families. Trees, shrubs and herbaceous plants are very common, dwarf shrubs show a more clustered distribution. These patterns may be indicative of the potential for trends and reversals. At a finer scale, it was concluded that biennials did emerge from annuals, whereas the reverse is difficult. All biennials are dicots.