F. M. Hexamer, Asparagus, its culture for home use and for market
“ As late as 1869 so keen an observer as Peter Henderson believed that "the asparagus of our gardens is confined to only one variety, and the so-called giant can be made gigantic or otherwise, just as we will it, and the purple top variety will become a green top whenever the composition of the soil is not of the kind to develop the purple, and vice versa. All practical gardeners know how different soils and climates change the appearance of the same variety. ”
