Details - Classification, evolution, and phylogeny of the families of Dicotyledons

Classification, evolution, and phylogeny of the families of Dicotyledons

Title

Classification, evolution, and phylogeny of the families of Dicotyledons

Related Titles

Series: Smithsonian contributions to botany, no. 58

By

Goldberg, Aaron

Type

Book

Material

Published material

Publication info

City of Washington, Smithsonian Institution Press, 1986

Notes

Includes index.

To some extent classification is subjective. Taxonomists differ in the relative importance they ascribe to particular characters and in the degree of difference between related taxa they deem sufficient to constitute family or ordinal rank. About 1000 dicot family names have been published. Those who have attempted an overview of the system at the family level and above in the last quarter century recognize between 274 and 455 dicot families in 39 to 82 orders. I accept 334 families and 59 orders. In Table 1 I give my ordinal allocation of the families and that of 11 recent authors to indicate where there is agreement and where there are differences to be resolved. I have also constructed a dendrogram to suggest relationships and degree of advancement of the orders.I have written concise, uniform descriptions of all the families of dicots, emphasizing those characters that show trends between families or occur in more than one family. Each family is illustrated by analytical drawings of the flower, fruit, seed and usually inflorescence. Several species are usually used to show the range of major variation within families and trends toward related families.Angiosperms probably arose from gymnosperms, so characters or character states universal in gymnosperms or considered primitive in them would also be considered primitive in angiosperms.My approach to understanding evolutionary trends in characters is to relate them to the ecological factors that might be responsible for them by their selective action. The dicots probably originated under warm temperate conditions favorable for growth. A major evolutionary trend in them has been the gradual development of characters and character states enabling them to cope with dry and hot or cold conditions and colonize generally unfavorable regions.A second major trend has been from wind pollination to progressively better adaptation for insect pollination. The primitive insect pollinated dicots often h