A study of the genus L̲a̲t̲h̲y̲r̲u̲s̲ : the genus L̲a̲t̲h̲y̲r̲u̲s̲, the sweet pea in botany and horticulture, classification of garden varieties of the sweet pea, winter flowering sweet peas

Front matter

A STUDY OF THE GENUS LATHYRUS

The Genus Lathyrus

The Sweet Pea in Botany and Horticulture I Classification of Garden Varieties of the Sweet Pea Winter Flowering Sweet Peas

Preface

This study was begun in the autumn of 1909. It has been carried on continuously under glass during two winters, and outdoors in the summer of 19 10. A collection of the obtainable species of Lathyrus, as well as a very extensive collection of the varieties of sweet peas, was grown at Ithaca. In addition to the above the writer was enabled to study the exhibits of outdoor-grown sweet peas at the annual exhibition of the National Sweet Pea Society at New York in July, 19 10, and of the winter-flowering varieties at Boston in March, 1 9 1 1 .

The investigation was begun with a view of studying the various species of Lathyrus for the purpose of monographing them, and particularly of detennining their value as ornamental plants. The studies on sweet peas included the evolution of the flower, as well as the preparation of careful descriptions and the detection and elimination of synonyms among present-day varieties. The descriptions of the garden varieties will appear in a later publication; those of winter-flowering varieties are included in Bulletin 3 1 9 of this station.

The author wishes to extend his thanks and grateful acknowledgments to Professor John Craig, who has given great encouragement, kindly advice, and all possible facilities for carrying on the investigation; to the National Sweet Pea Society for their cooperation in the variety tests; to the United States Department of Agriculture for seeds of species of Lathyrus; and to the seedsmen of the United States and Great Britain who contributed seeds for the trials. Among the latter, mention should be made of the assistance rendered by Messrs. C. C. Morse & Co. in contributing a collection of seventy-two varieties, representing various types and old or obsolete varieties, for the study on the evolution of the sweet pea.

Contents

Page

Part I. The genus Lathyrus 66 1 Botany of the genus 66 1

Artificial key to the species of Lathyrus 663

Descriptions of the species 667

History of the cultivated lathyrus 673

Descriptions of cultivated species 674