What is Garlic? A bit about Roots & Underground Stems
Me & Laura & the gang of boys were dragging the boat to the lake for Memorial Day last week, and found ourselves driving by the fields of garlic in Gilroy, CA. Somehow we got talking about whether garlic is really a root, bulb, tuber, a rhizome or something else. Then more questions started coming. Is it related to the onion? What about Leeks? Shallots? Scallions? I started answering the questions, and quickly found I had wandered from Fact to Lore and then ultimately to Fiction! I hate it when that happens, and so I did some research. It turns out the answer is complicated, and I had to add ‘corm’ to my list of relevant plant structures (I had never even heard of a corm!) Here’s what I learned:
First, there is a major distinction between an underground stem and a root. The vegetables we had questions about are actually underground stems, and not roots! A root grows underground (typically), absorbs minerals and water, and does NOT bear leaves or buds. Examples of roots include the carrot, turnip, parsnip, beet, jicama, radish, daikon and rutabaga! Factoid: I was surprised to learn that Swiss chard is actually the leaf of a type of beet!
Underground stems differ from roots in that they can sprout shoots, roots, leaves, and stems. It gets a bit more complicated since underground stems can be classified further based on their structure into rhizomes, corms, tubers and bulbs.
A rhizome is an underground stem that grows horizontally and has enlarged segments that store starch. Common examples of rhizomes are ginger, turmeric and ginseng. Interestingly, cardamom is a rhizome, although we only eat the seeds and not the underground stem portion. And, arrowroot is the starch from a rhizome.
A corm is a vertical stem that has a swollen, solid storage organ that looks somewhat like a bulb. The best example of a corm is taro. Corms can be transplanted and a new plant will grow from the corm.
Tubers are starchy storage organs that include the entire potato family as well as yams and yucca/cassava. Tubers can reproduce themselves, and the resulting plants are genetic copies of the parent plants.
Finally, we get to bulbs! A bulb contains a shoot that is surrounded by highly modified leaves that contain food reserves. Examples of bulbs include garlic, onion, scallions, shallots, and leeks. Chives are from plants that grow from bulbs, except we just eat the tips of the leaves! Green onions (and scallions) are just immature versions of an onion plant.
Now, back to the original question: garlic is a bulb!
– Chris