Plant Families : A Plea for International Sequence . 265 
According to Berry (1917) the practice of considering 
Angiosperms and Gymnosperms as sub-classes of the class Exogens 
was a no more pernicious mask of their true relations than the 
current usage which separates vascular plants into Pteridophyta 
and Spermophyta. He proposes seven groups : Angiospermophyta, 
Coniferophyta, Cycadophyta, Pteridospermophyta, Lepidophyta, 
Arthrophyta and Pteridophyta. 
Conard recently (1919) urges that it is no longer possible to 
discuss the relationships of plants in the terminology of currently 
accepted classification, that systematic botany is in immediate 
need of revision along major lines, and proposes a dichotomous 
arrangement: 
THALLOPHYTA. 
EMBRYOPHYTA. 
ATRAC HE ATA or Bryophyta. 
TRACHEATA or Vasculares. 
Lycopsida. 
Pteropsida (Aspermae or Ferns, Gymnospermse and 
Angiospermae). 
Uniform Families by Agreement. 
Slightly varying interpretations of the significance of 
characters, with corresponding variation in nomenclature, makes 
otherwise similar systems appear very different. In the past 
names now forgotten such as Phanerocotyledons, Acramphibrya, 
Rhizogens were given with a view to correspondence with other 
groups supposed to be co-ordinate. Agreement as to such main 
groups, even if obtainable, would have no important significance. 
Smaller groups have had a much greater stability. Ranunculaceae, 
Papaveraceae and numerous other family names are more than a 
century old. 
The number of families of vascular plants is generally 
considered as about 300. For a number no greater, might not 
agreement be possible, agreement for a given period not only as to 
scope but as to sequence ? A family sequence, as compared with 
a complete system of classification would have practical advantages. 
First, being as to many questions colorless it would be more 
suitable for wide agreement, for the main groups may be variously 
named and arranged without affecting family sequence. Second, 
revision would mean mainly a rearrangement of sequence without 
the introduction of new names. Thus successive lists might have 
a considerable degree of continuity. 
