Enlarged image of branching forms of bacteria from a clover nodule.

Photograph of two pots of red clover showing the effect of bacteria. The text beneath notes that no nitrogen is in the soil of either pot, but the pots are labelled, 'No N[itrogen]' and 'No N[itrogen] Bac[teria].'

Photograph of six samples of clover: a good sample of clover; a poor sample; dodder; weed seed often taken for dodder; dodder attacking red clover, the first stage and the final stage.

Photograph of three samples of plants, White clover (Trifolium ripens), Red clover (Trifolium pratense) and Bird's Foot Trefoil (Lotus corniculatus) with a graph beneath showing the total percentage of growth in the different plots of land.

Photograph of a herd of cattle standing in a clover pasture with a barn in the background in the early 20th century.