Corms look a lot like bulbs on the outside but they are quite different. They have the same type of protective covering and a basal plate like the bulb does, but do not grow in layers.
Instead, the corm is the actual base for the flower stem and has a solid texture. As the flower grows, the corm actually shrivels as the nutrients are used up. Essentially the corm dies, but it does produce new corms right next to or above the dead corm. It has contractile roots that bring down the corms as they rise up to the surface of the soil which is why the flowers come back year after year. Depending on the type of flower, it may take a couple years to reach blooming size.
A corm does not have visible storage rings when cut in half. This distinguishes it from a true bulb.
Many corms produce two different types of roots. Those growing from the bottom of the corm are normal fibrous roots, they are formed as the shoots grow, and are produced from the basal area at the bottom of the corm. The second type of roots are thicker layered roots that form as the new corms are growing, they are called contractile roots and they pull the corm deeper into the soil. They are produced in response to fluctuating soil temperatures and light levels. Once the corm is deep enough within the soil where the temperature is more uniform and there is no light, the contractile roots no longer grow and the corm is no longer pulled deeper into the soil.
The newly dug corms will have cormels that are pea size formed around the top of the old corm. The remains of the old corm will be directly beneath the newly formed corms. When the corm is cleaned up and the old stem removed, the growing point of the corm will be evident. The cormels can be saved and replanted in the back of the garden until they reach flowering size.
Examples of Hardy Corms – Crocus. Arisaema, Crocosmia, Liatris
Examples of Tender Corms: Gladiolus, Colocasia, Alocasia, Bananas (Musa), Ensete, Taro, Xanthosoma
Tunicate bulbs are some of the most familiar bulbs we come in contact with both in and out of our gardens.
Many underground plant structures are generally named bulbs. A definition of a bulb is a plant that incorporates its entire life cycle in an underground storage unit. Technically true bulbs are compressed stems surrounded by fleshy leaves acting as food storage organs. They are in the Monocot family of plants.
Bulbs can be further classified by looking at their various growth habits. Some of these “bulbs” are actually further classified as “true” bulbs, corms, tubers and rhizomes. Examples of these bulbs respectively are: narcissus, crocus, dahlia and canna.
True bulbs are represented by two classifications, tunicate and imbricate as represented by onions and lilies in that order.
Tunicate bulbs have a dry thin paperlike sheath surrounding them which helps to prevent them from drying and improves their storage capability. The basal base plate along with the tunicate sheath hold the bulb together. Roots emerge at the bottom of the basal plate.
We enjoy these bulbs both in the kitchen and in our gardens. Our cooking is enhanced by the addition of the tunicate bulbs of onions, garlic and shallots. The joyous colors in our early spring gardens are presented by our daffodils, tulips and hyacinths.
The term “bulb” is used by most people to refer to plants that have underground, fleshy storage structures. Only some of the plants commonly called bulbs actually are bulbs. The general definition of a bulb is any plant that stores its complete life cycle in an underground storage structure. These underground storage structures store nutrient reserves to ensure the plants’ survival.
Tubers, rhizomes, corms, and bulbs actually all serve the same purpose, just in a different way. They are each a storage unit for food that gives the plant the energy it needs to grow, bloom and complete its lifecycle each and every year.
The energy is created and stored by the foliage’s photosynthesis. You’ve probably heard that it’s important not to cut back the foliage after the bloom has died. That is because the leaves need to have time to absorb energy for next year’s bloom. Each storage system takes differing amounts of time to perform this task. Examples would be Alliums and Daffodils.
Bulbs or bulb-like plants are usually perennials. They have a period of growth and flowering. This is followed by a period of dormancy where they die back to ground level at the end of each growing season.
As with perennials, there are bulbs that are hardy in our climate and others that must be overwintered as house plants or placed in dormant storage.
Bulbs can be broken down into five types of storage structures. These include: true bulbs, corms, (stem) tubers, tuberous roots and rhizomes.
Daffodils are classified using two parts of the flower. For the purpose of this description, the daffodil is divided into two regions, the perianth (petals) and corona (cup). In further classifying daffodils the perianth (petals) is described by identifying first the outside edge of the petal, then the middle, and lastly the inside part next to the corona. The information I am providing in this article is gleaned from two sources, The American Daffodil Society … Continue reading →
BULBS Bulbs (which are referred to as “true bulbs”) grow in layers, much like an onion. At the very center of the bulb is a miniature version of the flower itself. It is composed of a shortened stem covered with modified leaves called scales. Helping the bulb to stay together is something called a basal plate, which is a round, flat area that are the beginnings of the roots on the bottom of the bulb. … Continue reading →
This large vase-shaped hosta emerges slightly behind some of my other hostas such as ‘Blue Cadet’. This slug-resistant architectural specimen is a commanding presence in my perennial garden. Though planted in full sun with absolutely no sunburn effects, I plan to divide it in the fall and put a portion of it in the woodland near the Hamamelis. I think their V-shaped structure will echo each other offering a nice rhythmic change of scale and … Continue reading →
There are so many stages of hostas that I enjoy seeing. None of them include slugs by the way. Having a shade garden I naturally grow many different cultivars of hostas. This particular one is named ‘Blue Cadet’ and was given to me years ago by my son Chris for Mother’s Day. Two Cadets and a Phlox subulata, I made out like a bandit! Each year I try to catch the hostas as they emerge … Continue reading →
My Garden and my Art go side by side. Both require me to make aesthetic judgments about composition, scale, color, texture and style. When I’m deciding where to plant the flowers I’ve hauled home on my endless trips to the nurseries it doesn’t seem that much different to me then when I’m deciding how to compose them on a two-dimensional surface. I think about what style I’m looking for, what colors will work together, whether … Continue reading →
Grape muscari, otherwise known as Grape Hyacinths live close to the ground. For years I never took much notice of them except for the little spots of brilliant purple that bounced so nicely against the bright yellow daffodils they bloomed along with in April. Then I got down. Hands and knees down. What a surprise! How intricate the little flowers are. Little bells dance around a central stem forming a small pyramid. This inflorescence changes … Continue reading →