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.
Corms of a dormant colocasia (Elephant Ears) and a crocus in bloom.
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.
Graphite Drawing of Onion and Garlic bulbs
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.
“Leeks and Pearl Onions” a graphite drawing by the Artist Mary Ahern
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 and Brent and Becky’s Bulbs. Both of these websites offer untold amounts of information and make enjoying the spring displays even more rich.
The Daffodil Society even has downloadable & printable coloring books for those individuals who work with children’s groups. Brent and Becky’s information filled Fall Bulb catalog arrived just in time for Spring so that we can go out to view daffodils in other gardens and make a list for next year’s display.
All daffodils are classified into one of the thirteen divisions described below:
Division 1 – Trumpet
One flower to a stem, corona (trumpet or cup) as long or longer than the perianth segments (petals).Trumpets usually produce larger bulbs than other divisions. Most have gray/green foliage ½” – 1” wide
Division 2 – Large Cup
One flower to a stem, corona (cup) more than one third but less than equal to the length of the perianth segments (petals).The group that you see the most often used in gardens; perfect for perennializing, picking, forcing and showing; some of the showiest daffodils are in this division and are the ones that give you more ‘bang for your landscape buck’.
Division 3 – Short Cup
One flower to a stem, corona (cup) not more than one third the height of the perianth segments (petals).These are long term perennializers, show flowers and late season picked flowers, often with a spicy fragrance.
Division 4 – Double
Daffodils have a clustered cup, petals or both. There can be one or more flowers per stem.Camellia or roselike flowers; with single of multiple blooms; good for shows, showy gardens, picking and bedding.
Division 5 – Triandrus
Usually more than one flower to a stem, head drooping, perianth segments often reflexed and of silky texture.Fuchia-like blooms often with a fruity fragrance; great in containers.
Division 6 – Cyclamineus
One flower to a stem, perianth significantly reflexed and corona straight and narrow. Some exceptions exist.With their faces looking like they are standing in front of a fan, they look & perform wonderfully in pots & are terrific for forcing; seem to be more tolerant to partial shade moisture as a group.
Division 7 – Jonquilla
Usually several flower heads to a stem, flowers usually fragrant, stem is round in cross-section and foliage is often rush like.Foliage is often reed-like or at least very narrow & dark green. Most like the hot baking summer sun. Better in southern gardens but some are adaptable in cooler climates. Sweetly fragrant. Most are great in pots.
Division 8 – Tazetta
Usually three to twenty flowers to a stout stem, sweet scented and very short cupped. Perianth segments rounded and often somewhat crinkled.Excellent perennialzers with a musky, sweet fragrance; good for Southern gardens & forcing.
Division 9 – Poeticus
Usually one flower to a stem. White petals sometimes stained with the corona color at the base, small flat cup edged with red.Excellent perennials with a spicy fragrance, dogwood-like blooms; good for picking.
Division 10 – Bulbocodium Hybrids
Usually one flower to a stem. Perianth segments insignificant compared with Corona.Cultivars in this division are offspring of the species bulbocodium conspicuus, often referred to as ‘Hoop Petticoat’.
Division 11 – Split Corona
Corona split – usually more than half its length.A division where the cup of the daffodil is split into segments & spreads back against the petals. Sometimes the cup is smooth, often it’s frilly & many other times it’s in between.11a) Collar Daffodils Split-corona daffodils with the corona segments opposite the perianth segments; the corona segments usually in two whorls of three11b) Papillon DaffodilsSplit-corona daffodils with the corona segments alternate to the perianth segments; the corona segments usually in a single whorl of sixColoration of the corona often appears in sunburst-like streaks.
Division 12 – Other Cultivars
Daffodils not falling into any of the previous categories.
Division 13 – Species All species and reputedly wild forms.
Ones that are referred to as species daffodils & most of which are Heirloom & suitable for restoration gardening from 1700 on.
All photos are from the Brent and Becky’s 2013 Fall Catalog.
Disclosure: We receive NO financial or other consideration from either of these organizations for linking to their websites.
Brent and Becky’s Bulbs.. Either read their print catalog or view their digital catalog online.
American Daffodil Society. Visit and learn from their information filled website.
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