Ch.19- Classification and Systematics

Phylogeny

The hereditary relationships of any group of organisms.

Modern plant systematics

The goals of modern plant systematics are to understand evolutionary lines and to have a system of names that accurately reflects their relationships.

Species

A set of individuals closely related by descent from a common ancestor, which is the most fundamental level of classification.

Genus

A group of closely related species that share a common ancestor.

Family

A higher taxonomic category composed of one or more genera.

Cladistics

A method of analyzing phylogenetic evolutionary relationships based on shared derived characters (synapomorphies) and convergent evolution (homoplasies).

DNA Sequencing

A tool used to study evolutionary relationships by examining DNA directly and identifying mutations.

Cladogram

A diagram that shows evolutionary patterns and the divergence of taxa from a common ancestor.

Paraphyletic group

A group that does not contain all the descendants of the most recent common ancestor.

Synapomorphies

Shared derived characters used to infer phylogenetic relationships.

Parsimony

A principle used to infer phylogenetic trees by selecting the simplest explanation that requires the fewest evolutionary changes.

Clade

A group of species and their common ancestor.

Basal angiosperms

Early angiosperms that diverged before the split of monocots and eudicots.

Eudicots

Angiosperms excluding monocots and basal angiosperms.

Type specimen

A single preserved plant that carries the name of a new species.

Isotypes

Specimens similar to the type specimen.

Three domains

Bacteria, Archaea, and Eukarya, representing major evolutionary lines.

Key

A tool used to identify plants by following a series of choices (couplets) based on plant characteristics.

Simple leaf

A leaf with one blade per leaf.

Compound leaf

A leaf with more than one leaflet per leaf.

Leaf margins

Dentate (triangular tooth-like teeth) and serrated/toothed (sharp saw-like teeth).