The Joyful Botanist: Rooting for you
A freshly dug poke root (Phytolacca americana) looks like a person running.
Adam Bigelow photo
When you see a plant growing, flowering and fruiting in a garden, field, forest or pot you’re only seeing a part and not the whole. Much of the plant exists below the ground in the soil in the form of roots. It’s common to think that half of the plant is aboveground — stems, flowers and leaves — and half is below the ground in the roots, but this is not true across the board.
Many giant trees, including the tallest and largest in the world like the coastal redwoods (Sequoia sempervirens) and the giant Sequoia (Sequoiadendron giganteum) have shallow roots and are as much as 70% above-ground. While some prairie wildflowers like the cylindrical blazing star (Liatris cylindrica) only grow to a height of two feet at most, they can have roots that penetrate 15 feet into the soil and comprise 80% of the plant’s mass.
Roots are powerful parts of a plant and do more than just hold it up in the soil. Plant roots store solar energy that a plant’s aboveground parts have converted to sugar and carbohydrates through photosynthesis. Plants “eat” sunlight and convert that energy into a form it can transport and use for many of its biological processes. The main place the plant stores this energy is in the root. We consume this stored energy when we eat roots like carrots (Daucus carota ssp. sativus), beets (Beta vulgaris), radishes (Raphanus sativus), parsnips (Pastinaca sativa), sweet potatoes (Ipomea batatas) and yams (Dioscorea spp.).
You may wonder why I didn’t list potatoes (Solanum tuberosum), onions (Allium cepa), ginger (Zingiber officinale) or garlic (Allium sativum). These plant parts may grow underground or at the soil’s surface and may look like roots, but botanically speaking, these parts are actually modified stems that have been adapted to serve root-like roles.
So, what exactly is a root then?
In botany, roots are defined as a part of a plant that is normally underground (but not always) and is primarily used to anchor the plant in the soil, take up and distribute water and nutrients and hold reserve energy, as previously stated. Roots differ from stems by lacking leaf scars and buds and having branches that emerge from internal tissue and not from buds like stems do. And plant roots help hold soil together and keep it from eroding.
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There are many different types of roots. Carrots, dandelions (Taraxacum officinale) and black walnut trees (Juglans nigra) have what is called a taproot. The taproot is a main, central root that primarily grows straight down and often has lateral roots branching off. Taprooted plants are usually anchored deeply in the soil and are difficult to remove.
There are fibrous roots, made up of multiple dispersed roots that form a matrix or web in the soil and are spread out from the plant’s center. Fibrous roots are great at scavenging for water and nutrients and are often connected at their tips to fungal strings or mycellium which help expand the roots’ reach and ability to collect water and nutrients. The fungi do this in exchange for some of the extra sugars and carbohydrates the root is holding. Grasses and many herbaceous wildflowers have fibrous root systems.
Another type of root structure is not found under the ground but growing on the aerial or aboveground parts of the plant. These are called adventitious roots, and they serve multiple functions. Adventitious roots can remain dormant until the plant breaks and falls to the ground or is covered by soil. Then, they break dormancy and begin to grow, effectively creating a clone of the parent plant. This advantage of adventitious root systems is why you’ll find these on many plants that grow along creeks and riverbanks.
No matter how you are spending this long and cold winter, know that out there beneath the snow and just under the soil surface, roots are growing. Plants are rooting for themselves and rooting for their future. Maybe the plants are rooting for you, too. I know I am.
(The Joyful Botanist leads weekly wildflower walks most Fridays and offers consultations and private group tours through Bigelow’s Botanical Excursions. This email address is being protected from spambots. You need JavaScript enabled to view it..)
