EVOLUTIONARY ASPECTS OF LIFE FORMS IN ANGIOSPERM FAMILIES

The distribution patterns of life forms among extant families, subclas ses and classes are described with the aim of detecting evolutionary t rends. The explosive diversification of angiosperms constrains the pos sibilities for detecting such trends. Moreover, the extant groups of s eed plants are only a small sample from the historical diversity. Neve rtheless, we could distinguish between common, scattered, clustered, a nd rare distribution patterns among groups of families in subclasses. The rare category may represent specialized life forms, including epip hytes, carnivorous plants, (hemi)parasites, saprophytes, succulents, x erophytes, 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 mor e clustered distribution. These patterns may be indicative of the pote ntial for trends and reversals. At a finer scale, it was concluded tha t biennials did emerge from annuals, whereas the reverse is difficult. All biennials are dicots.