The Bases of Angiosperm Phylogeny: Vegetative Anatomy

Abstract

J I P nn " pal , char acters of vegetative anatomy which are of phylogenetic significance at the higher levels in angiosperm systematics are defined and discussed in relation to their taxonomic distribution in the Takhtajan and the Cronquist systems of angiosperm classification. In absence of a complete fossil record, application of the phylogenetic method of association, correlation, and common ground plan are illustrated from anatomical data Vegetative structure contains a wealth of potentially significant systematic information' However only the evolutionary trends in the secondary xylem and the phylogenetic conclusions that have resulted from recognizing these trends, provide a firm basis of angiosperm phylogeny. In order for the phylogenetic significance of other vegetative anatomical characters to be fully realized more comprehensive studies must be undertaken and new methodologies and approaches applied. For the most part, anatomical data support the at tteheVr 10nS ,° f ?* ? khtajan u^ Cr ° nquist SyStemS of angiosperm clarification SJrJSSf taX °"°r C f eIS r However > ^ e r° St reliable application of anatomical informaof close affin% Stat6mentS ° f n6gati ° n ° f dose relationship rather than positive assertions Anatomical characters have been employed for systematic purposes well over

Ecological significance of wood anatomy of Alseis pickelii Pilg. & Schmale (Rubiaceae) in a Tropical Dry Forest

“…Therefore, it is important to describe wood anatomy including its several constituent cells types and their function, organization and structural peculiarities. Moreover, comparative anatomy provides benefits to phylogenetic studies of ecological strategies, because it is possible to examine structural changes under different environmental pressures (Dickison 1975).…”

Variation in xylem structure from tropics to tundra: Evidence from vestured pits

“…The evolution of xylem vessels has been considered a key adaptation marking the pinnacle of hydraulic efficiency in flowering plants, because plants with vessels generally have higher hydraulic conductivities than plants that rely solely on tracheids for water transport (5). The traditional view is that evolutionary trends of vessel elements have been regarded as reliable tools in the study of angiosperm phylogeny, because vessel characters were considered conservative traits containing a wealth of potentially significant systematic information (2,6,7). Although parallel development of vessel characters is generally accepted, recent phylogenetic analyses of angiosperms suggest there have also been some reversals in the Baileyan transformation series (8,9).…”

Ecological interpretations of the leaf anatomy of amphibious species of Aeschynomene L. (Leguminosae - Papilionoideae)

“…For Dickison (1975), some types of trichomes came from independent lineages, and could have no importance in taxonomic and phylogenetic studies. In our study, the hydathode trichome was exclusive in the species of the evaluated series Indicae and Sensitivae, in which the species are distributed in wetter areas (Lima et al, 2006).…”