Basic Plant Identification: Part 1

Henbit and purple nettle
To the left, Purple Dead Nettle (Lamium purpureum) and to the right, Henbit (Lamium amlexicaule)

A few weeks ago when I was talking about my love of sidewalk weeds and identifying plants, some of you had written to me saying you wanted to learn more.  In my last post on this topic we talked about some characteristics of plants but I was unable to show examples due to the time of year and the slim pickings of available plant life.

So let’s start with the photograph at the top of this page. These plants seem to look almost the same at a quick glance and many times people either mistake the one for the other or do not realize at all they are entirely different plants.  They are common lawn “weeds” so you have probably seem them before. They are in the same family (Lamiaceae) and the same genus (Lamium)  but are different species.   As I mentioned before, it is often difficult to be able to key a plant down to the species. If you (as an amateur like myself) get to the genus that is pretty good but if you can actually just look at a plant and identify the family, that is excellent.

Example of “opposite” arrangement of leaves

For these plants, lets start with the leaves.  The example above is called opposite leaves because the leaves are directly across from each other along the stem.  The example below show leaves that are called whorled because the leaves surround the stem (think of it as lots of opposite leaves together rather than just two).

Whorlled leaves
Example of “whorled” arrangement of leaves

Another characteristic of leaves that is important are the edges of the leaves. The examples we have here (see below for a close up) fall into the category of toothed edges because the edges of the leaves have little teeth (as opposed to being smooth).  In out last post  on this topic, we looked at wild ginger leaves that had a smooth edge and that was called an entire leave.

toothed or lobed edges
Examples of “toothed” edges of leaves

Here is another characteristic to look for: the shape of the stem. Notice in the close up below that the stem is square (I just am showing one but both these plants have a square stem).

square stem
Square stem

So now you know what a Toothed leave is.  You also know two very important characteristics (opposite or whorled leaves and square stems) of a very common plant family: Lamiaceae.  Why should you care? Well, the family Lamiaceae is more commonly known as the mint family.  Next time you tend to your basil, oregano, thyme, or rosemary plants take a look at the position of the leaves and feel the stem.  Now there are other characteristics that make these plants part of the mint family. It is important to know that because there are also other plants with opposite leaves and square stems that are not part of the mint family and perhaps we can look at those characteristics another time.  But for now, pat yourself on the back for getting to know the members or your herb garden on a different level.

5 thoughts on “Basic Plant Identification: Part 1

  1. I am sitting in front of this marvelous description on mints after a wonderfully refreshing hike along the Schuylkill trail with gratitude exuding from my pores for the 70 degree middle March weather with the strong urge to be at our cottage and start digging in my herb garden. That would be so much better than disinfecting keys and watching the stock market tumble.

    Thanks for sending. Sheldon


    1. I knew the morning of the day we were to leave, that it would not happen. We called Road Scholar and canceled out. What a relief! They were very cooperative and supportive, and allowed us to use the insurance at that last-minute time. Although we are in the midst of a very unsettling time, we are happy to be safe and comfortable in our home. Best, S.


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