The plant world is full of confusing terms. From scientific names to two completely different plants sharing the same common name, as well as a mass of different groupings and classifications, it’s hard to know where your favorite plant fits in the chaos.
The beloved tropical plant Hibiscus is not exempt from this confusion. In fact, more confusion surrounds this plant than usual. Questions like, ‘is Hibiscus an annual or a perennial?’ or ‘what’s the difference between Rose of Sharon and Hibiscus?’ are common. When it comes to classification, there are many more. Is the Hibiscus an herb or a shrub? Is it a tree?
By providing some clarity on these classifications, you should feel more confident in your plant knowledge, and within plant care too.
Understanding Plant Classifications
The differences between herbs, shrubs, and trees lay mainly in their stems, but also in their size and growth habits. The terms are often used interchangeably, especially when it comes to shrubs and trees, but there are a few key factors that separate these groups.
The stems of herbs are soft and non-woody, described aptly as herbaceous. Shrubs and trees on the other hand have woody stems, with the woody stems of trees usually harder and thicker than those of shrubs. This distinction is the reason banana ‘trees’ are technically herbs, and a plant labeled an herb in the kitchen – rosemary – is actually a shrub.
Telling the difference between a shrub and a tree is slightly more difficult. As they both have woody stems, the key is in the branching. Shrubs typically have several branches beginning at the base of the plant, whereas trees have a central trunk with branches spreading from that point.
Another way to tell the difference between these plants, which may not always be accurate but provides a quick guide if you’re stuck, is size. Herbs are typically smaller, shrubs slightly bigger at a maximum of 13 feet, and trees the biggest of all the plants. This is not a reliable rule though, as the banana tree debacle indicates.
As with all things in gardening, there are exceptions to the rules. For example, the Japanese maple (Acer palmatum) is certainly considered a tree, but it has multiple branching trunks that separate at the base. However, these general distinctions are enough to classify most garden plants, leaving room for the occasional outlier.
What is a Hibiscus?
With those definitions cleared up, let’s apply them to determine whether a Hibiscus is an herb, a shrub, or a tree.
Is Hibiscus an Herb?
The Hibiscus genus is full of variety. Whether it be the range of colors, leaf shapes, or flower types, the range of plants found under the name Hibiscus is vast. It should follow that at least one of the varieties, if not more, are considered herbaceous. And it does indeed.
Hibiscus moscheutos, also known as the Dinnerplate Hibiscus or Hardy Hibiscus, is often classified as an herbaceous perennial. While this variety grows quite large and features even larger flowers (the size of dinner plates, in case it wasn’t clear in the name), the stems are far softer than their relatives.
The stems are softer, but they do have a slightly woody quality. Its branching habit also leans more toward the shrub side than the individual stems of most herbaceous plants.
While this herb classification is certainly as close to the border between the two as you can get, it usually holds up.
Is Hibiscus a Shrub?
As a whole, plants in the Hibiscus genus are normally called shrubs. This is a safe bet, as most of the well-known varieties are considered shrubs. The Rose of Sharon, Chinese Hibiscus, and Fiesta Hibiscus, are popular plants in many home gardens, are examples of shrubs.
These plants are given this label largely due to their woody stems. The stems can be on the thinner side but if left to grow may thicken quite a bit. The many branches also separate from the base, distinguishing it from a tree.
When it comes to size, telling what group Hibiscus falls into is almost impossible. Some dwarf cultivars may be much shorter than other herbaceous plants, even growing well in containers indoors. Other herbaceous Hibiscus varieties, like Hardy Hibiscus, could be larger than their shrub relatives. Due to the extensive hybridization and cultivation of these plants, size usually doesn’t tell the whole story.
Is Hibiscus a Tree?
To make matters even more confusing, Hibiscus is not usually considered a tree, but it can be grown as one. It’s a tough concept to wrap your head around – trust me, I know – but it’s not difficult to see why when you understand the process.
Hibiscus varieties that are normally labeled shrubs can be trained to grow into trees, given the right conditions. This is done by cutting back the several branching stems and leaving one strong branch to become the central trunk. The other branches are cut right down to the soil line, leaving only one branch standing.
From there, other lateral branches are pruned all the way up the trunk, leaving the bottom two-thirds of the tree bare. The result is a very tree-like plant with a small, laterally branching canopy of stunning flowers. Any emerging branches are cut back to maintain a tidy tree appearance. It may be a small tree, but when cut back this way, it is considered more tree than shrub.
Which Classification Fits Best?
Although it may not be a clear, satisfying answer, Hibiscus technically could be an herb, a shrub, or a tree. When looking at the Hibiscus genus as a whole, shrub is definitely the most apt description.
Most varieties have woody, branching stems that remain that way without a gardener’s intervention. However, some varieties with softer stems could be considered herbs, and most varieties could be trained to form a tree. But luckily, anyone growing a Hibiscus will have a stunning flowering plant, no matter what classification you give it.