Trueness of Herb Cultivars from Nurseries
Answered by: Conrad Richter
Question from: Steven
Posted on: June 03, 2010

I am concerned with the issue of cultivator purity. As I search for herbs at local nurseries (in Birmingham, Alabama), the various kinds are often labeled as specific cultivars. How can I know if these are true to the original plants? Specifically, do nurseries and their suppliers typically propagate perennial hebs asexually so that I am getting a ‘clone’ of the original? How concerned should I be on this issue?

You touch on an important issue that is both misunderstood and under-appreciated by many. Thank you for bringing it up.

All plant and seeds are sold labeled with a name that is referred to as the "variety" or common name. There is a more precise and more limited botanical meaning for "variety" in taxonomy; but in the everyday sense "variety" is a loose term that can refer to a) species, b) vegetatively cloned cultivars, and c) seed-propagated varieties such as selectively-bred seed varieties and hybrid seeds. To a non-professional (and to many professionals too) this all can be quite confusing.

At every level at which variety names are used -- whether at the botanical species level, the cultivar level, or the seed variety level -- the variety can be compromised by two different problems. The first is the problem of mis-identification, a problem since the time when farmers first selected plants with superior traits. Most often the mis-identification is unintentional, the result of vendor or grower error, or error on the part of the supplier to the vendor or grower. This problem is surprisingly common in commercial horticulture today. There is a plethora of varieties and species on offer today and growers and vendors often do not know the varieties well enough to know when their material is mis-identified. In today’s inter-connected web of commercial horticulture, when growers are no longer keep their own stock plants and growers no longer save their own seeds, there are ample opportunities for mistakes. All of this is compounded by the problem of indequate reference materials for checking the identity of plants. Varietal differences are often so subtle that it is difficult for even a dedicated collector to tell the varieties apart.

The second problem is the one suggested by your question about "purity". It is not uncommon for varieties to be contaminated with plants or seeds that are not true to the original variety as developed by the breeder. This happens when off-type plants or seeds get mixed with the variety or when seed varieties cross with other varieties if the seed grower is not careful to keep varieties separate in the seed production fields. Varieties can also naturally degenerate over time. We have seen degeneration in Dark Opal basil which used to be pure dark purple and now has a mottled purple and green look. We also see it with variegated herbs which can lose their variegation unless the grower takes care to remove off-types regularly.

There is no ironclad way to be sure of the identity and purity of herbs. The best you can do is to buy from reputable growers who know their product. It is generally safer to buy herbs from herb specialists than from corner stores, hardware stores or big box stores that stock herbs. I cannot tell you how often I have seen mislabeled herbs sold by people who just don’t know their herbs. Imagine summer savory being sold as oregano! My impression is that mis-identification in the industry is getting worse.

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