Kohl Characters

Posted in Gardening Tips on March 22 2011, by Sonia Uyterhoeven

Sonia Uyterhoeven is Gardener for Public Education.

The mention of genetic manipulation is often met with suspicion in the botanical world, yet if we look back into our past we will discover that it has been an important and well worn horticultural practice. Charles Darwin dove into the treasure troves of early 19th century hybridizers to help piece together his theory of evolution.

Long before then, genetic manipulation was a staple in horticultural practice. Hybridizers were constantly on the look out for specimens with desirable traits – whether it was larger fruit, early maturity or interesting foliage. Cabbage and the other members of its illustrious family have a long history of change. Some sources say these changes started back as early as the 5th century B.C.

While cabbages, cauliflower, broccoli, kale, kohlrabi and Brussels sprouts are viewed as distinct vegetables by gardeners, they all originally come from the same species – Brassica oleracea. Centuries of careful selection has lead to the variety of vegetables that end up on our table.

Wild cabbage or sea cabbage (Brassica oleracea) is a Mediterranean cliff plant that looks a lot like kale. This maritime plant is salt and lime tolerant. It is not a good competitor so it grows on hillsides. Wild cabbage is a biennial that takes 2 years to flower and set seed – the flower can reach 3-7 feet in height. The leaves that form a rosette in the first year are high in nutrients and vitamin C – ancient Greeks and the Romans relied on it as a food source.

Over time, through selection, different parts of the plant was modified and selected for. Kale was one of the first descendents. Its botanical name Brassica oleracea var. acephala means ‘cabbage without a head’. Wild cabbages with tight clusters of leaves were selected for over time and these eventually turned into heads. Our cabbage (pictured) Brassica oleracea var. capitata means ‘cabbage with a head’.

The Germans developed a taste for fleshy stems and breeding practices resulted in the ‘stem turnip’ or what we know as kohlrabi (Brassica oleracea var. caulorapa). The Italians developed a taste for immature flower buds hence the introduction of broccoli (Brassica oleracea var. italica). Brussels sprout (Brassica oleracea var. gemmifera) as you have probably figured out by now were bred by the Belgians and given the name ‘cabbage bearing gems’.

Every vegetable has a history to tell; it is our job to trace and understand it. Looking back on thousands of year of breeding certainly gives me a great appreciation for the plasticity of plant material and the amount of variation that is always present in species.