What Are Herbaceous Plants? A herbaceous plant is a plant that by definition has a non-woody trunk, but annuals go a step further and can have an underground plant, part of the root or tuber that survives. In winter, the above ground growth in temperate zones dies off largely or completely, and the below ground growth (temperate zones) dies off. Annual plants die during the growing season, so they cannot really be “herbaceous” in the sense that annual plants are “non-woody.”
The question of whether or not a plant is “herbaceous” depends on the age of the plant, the size and shape of its trunk and the type of woody stems. If a two-year-old herb can be described as herbaceous, it must have a non-woody trunk and no woody trunks, but it retains its so-called base leaves in winter.
Herbaceous Plants That Are Perennials
When we talk about herbaceous plants, we usually limit the discussion to perennials, even though they are the most common plant species in the world.
These are non-woody plants that die back on the ground after the return of colder temperatures. As evergreens, perennials themselves are almost synonymous with the Northern Lights. This group includes some of the most valuable plants in the landscape, but they are not the only ones.
Everyone immediately thinks of perennials, those specialized plant parts that patiently survive the winter on the surface. But even among the general classification of perennials, there is a subclass based on how plants absorb nutrients when the weather warms up enough to produce vegetation again. Perennials have roots that survive underground during the winter, but they have no roots at all, only specialized plant parts such as leaves and stems.
The plant parts that store nutrients underground are classified as tubers similar to the tuber. Daffodil is a well-known example of a perennial plant with tuber – like roots, but no roots. There are, for example, spring bulb plants that take on all phases of spring, then leaves and stems and an early bloom.
They don’t flower in summer, but they do overwinter indoors, so bring them to emerging tropical countries like Australia, New Zealand, South Africa or South America.
Other herbaceous plants, however, behave more like corals, which serve as an underground food reservoir, than as a source of food for plants.
One example is Japanese knotweed (Polygonum cuspidatum), which stores its plant food in its underground rhizomes. Although some gardeners resent the name, this weed is a permanent plant, and weeding usually requires more effort than removing the annual weed. The giant snake lily (Amorphophallus konjac) emerges from the grain in spring and is known for its smelly joints, which are said to attract beetles that feed on animal carcasses.
What Are Underground Rhizomes?
The rhizome typically grows horizontally, just above the Earth’s surface, with a diameter of about 3 to 4 cm and a length of at least 2.2 inches.
Herbaceous Plants in a Northern Winter Landscape
Perennials are dying off again, but that doesn’t mean they’re necessarily disappearing; two-year-old, root-bare leaves are unlikely to stick to snow in the north, and annuals are already dead when winter arrives. But that gives us little hope of arousing winter interest in herbaceous plants.
Sometimes the growth on the ground remains attractive even after their death, and sometimes they get browned, let alone hung for a few months.
So gardeners often struggle with whether or not to cut, and the basic answer is that if there is no disease, it is perfectly fine not to cut plants in spring. In fact, soil and vegetation can even provide a little insulation to help plants survive the winter.
Joe-Pye weed (Eupatorium; adds architectural interest) Coneflowers (Echinacea; wild birds eat the seeds) Maiden grass (Miscanthus; the straw color its leaves assume in winter is pretty)
However, do not forget to add an evergreen tree or shrub to your herbaceous plants as you like, as the latter offer more winter interest in the landscape.