As a firm believer in science and somewhat of a compulsive about classifying and ordering things, I have this odd dissatisfaction with how difficult it is, especially for an amateur to positively identify a particular species of plant. There are a number of reasons for this of course, some of which I will get into at the end of this article. Firstly though, let’s try to get at the heart of the problem. In the photo above, there are two instances of what seem like distinct plants. Here’s how I identified them along with my line of reasoning.
Often I’ll find myself driving on the Oregon Coast and trees like the one on the left will appear, increasingly so as we approach the state of California. After some research, I’ve concluded (perhaps erroneously) that these must be local cultivars of Cordyline Australis and definitely not members of the similar looking and related Yucca genus. My reasoning was simple and exactly what you’d expect from a newbie plant enthusiast. Using Google Images, I looked up various species of yucca grown around the West Coast, did the same for popular cordyline species and just kind of arbitrarily decided that these were cordylines. How’s that for science!
Virtually all department stores and nurseries in Oregon will sell the plant on the right. They are often labeled “Spike”, “Dracaena Palm”, “Cordyline Indivisa”, “Cordyline Australis” or just simply, “Cordyline”. I have examined these plants very closely and I am fairly confident that these are just synonyms for the same plant. Sold and marketed as annuals in Zone 8, they are generally sold as landscape or outdoor plants. More research will reveal that if overwintered, these will eventually form a trunk and in time could become full-blown trees that very much, once again, look like Cordyline Australis. Putting two and two together, the natural conclusion must be that since the Oregon Coast is generally closer to a Zone 9a climate, people plant these “Spikes” in their yard, which survive their mild winters and eventually become mature trees that closely resemble those in the left photo. Here’s another example:
Well, the short answer is, because plants are complicated. From the perspective of plant merchants, it doesn’t really matter as long as we all kind of agree on a “close enough” synonym.
For a slightly longer answer, I have spoken with an expert in the field and have also found an interesting article on the subject.
First of all, there is a tremendous amount of disagreement even between accomplished botanists on the taxonomy and classification of plants. Entire plant families are continuously broken up or moved around in their classification. Read this short Wikipedia article if you are not convinced.
Furthermore, it is extremely difficult to positively identify a plant from its size and leaves alone. To make things even more complicated, plants–like people, can look decidedly different in their early years than later in life. Thus, to positively identify a plant, one not only has to know the currently accepted scientific name, but also thoroughly examine its overall shape, leaves (along with their undersides), stem lengths, petioles, flowers, root shape/color, etc.
So that kind of kills my idea right there of a working “Shazam for plants” app. So is that it? Are plant lovers forever left to second-guess themselves with conflicting and questionable internet and garden center data? Fortunately, I think we can do better. Stay tuned.