An Illustrated Flora of the Northern United States, Canada and the British Possessions/Dicotyledones

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Class 2.
Sub-class 1.
Monocotyledones

An Illustrated Flora of the Northern United States, Canada and the British Possessions
Nathaniel Lord Britton & Addison Brown

second edition
Subkingdom Spermatophyta
Class 2. Angiospermae
Sub-class 2. Dicotyledones

Series 1.
Choripetalae
(Petals distinct, or none)

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1157831An Illustrated Flora of the Northern United States, Canada and the British Possessions — second edition
Subkingdom Spermatophyta
Class 2. Angiospermae
Sub-class 2. DicotyledonesNathaniel Lord Britton & Addison Brown

Sub-class 1. Dicotylédones.

Embryo of the seed with two cotyledons (in a few genera one only, as in Cyclamen, Pinguicula and some species of Ranunculaceae and Capnoides), the first leaves of the germinating plantlet opposite. Stem exogenous, of pith, wood and bark (endogenous in structure in Nymphaeaceae), the wood in one or more layers surrounding the pith, traversed by medullary rays and covered by the bark. Leaves usually pinnately or palmately veined, the veinlets forming a network. Parts of the flower rarely in 3's or 6's.

Dicotyledonous plants are first definitely known in Cretaceous time. They constitute between two-thirds and three-fourths of the living angiospermous flora.

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Series 1. Choripetalae.

Petals separate and distinct from each other, or wanting

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Series 2. Gamopetalae.

Petals wholly or partly united, rarely separate or wanting