UNITED STATES DEPARTMENT OF AGRICULTUREBULLETIN No. 844Contribution from the Bureau of Plant IndustryWM. A. TAYLOR, ChiefWashington, D. C.PROFESSIONAL PAPERAugust 11, 1920SWEET-CLOVER SEED
BULLETIN No. 844
Contribution from the Bureau of Plant IndustryWM. A. TAYLOR, Chief
ByH. S. Coe,formerly Assistant Agronomist, Office of Forage-Crop Investigations, andJ. N. Martin,Professor of Morphology and Cytology, Iowa State College.
PagePart I.—Pollination Studies of Seed Production.Unsatisfactory yields of sweet-clover seed1Previous investigations of the pollination of sweet clover2Outline of pollinating experiments3Structure of the flowers of Melilotus alba4Development of the floral organs of sweet clover5Fertilization in Melilotus alba8Development of the seed8Mature pollen of sweet clover9Germination of the pollen9Cross-pollination and self-pollination of sweet clover10Artificial manipulation of sweet-clover flowers10Seed production of Melilotus alba under ordinary field conditions13Efficiency of certain kinds of insects as pollinators of sweet clover14Relation of the position of the flowers on Melilotus alba plants to seed production19Influence of the weather at blossoming time upon seed production20Insect pollinators of sweet clover21Effect of moisture upon the production of Melilotus alba seed22Part II.—Structure and Chemical Nature of the Seed Coat and its Relation to Impermeable Seeds of Sweet Clover.Historical summary26Material and methods30Structure of the seed coat31Microchemistry of the seed coat33The seed coat in relation to the absorption of water34A comparison of permeable and impermeable seed coats34The action of sulphuric acid on the coats of impermeable seeds35Literature Cited36
Part I.—Pollination Studies of Seed Production.
Relation of the position of the flowers on Melilotus alba plants to seed production
Part II.—Structure and Chemical Nature of the Seed Coat and its Relation to Impermeable Seeds of Sweet Clover.