Yes, a “mum” is a chrysanthemum. The shortened, familiar name is used universally for this popular fall-blooming plant, which belongs to the genus Chrysanthemum. This genus contains numerous species and thousands of cultivated varieties prized for their vibrant, late-season color and diverse flower forms. Native primarily to East Asia, particularly China, the chrysanthemum has been cultivated for over 3,000 years. Its popularity as an autumn decoration is due to its ability to produce abundant blooms when many other garden plants are fading.
The Botanical Classification
The connection between the common name “mum” and the scientific name Chrysanthemum is rooted in the system of plant classification known as taxonomy. The genus Chrysanthemum falls within a very large plant family called Asteraceae, which also includes daisies, sunflowers, and asters. The scientific name is always written with the genus capitalized and the species name in lowercase, both italicized, to uniquely identify the plant.
The most widely grown and commercially significant chrysanthemum is the complex hybrid known as Chrysanthemum × morifolium. The “×” symbol indicates that this plant is a hybrid, a blend of several different wild species cross-bred over centuries to create the modern garden mum. The interchangeable use of “mum” and “chrysanthemum” reflects that nearly all cultivated varieties belong to this single, highly developed genus.
Physical Characteristics and Forms
The structure often mistaken for a single flower on a chrysanthemum is actually a composite flower head called a capitulum. This head is composed of dozens or even hundreds of much smaller individual flowers, known as florets, grouped tightly together. These florets are divided into two distinct types: ray florets and disc florets.
The ray florets are the showy, petal-like structures that form the outer ring of the flower head. These florets are female and bilaterally symmetrical. The disc florets are the tiny, often inconspicuous flowers that form the central “eye” of the bloom, and they are typically hermaphrodite, containing both male and female reproductive parts.
Centuries of hybridization have resulted in an extraordinary range of flower shapes, which are classified into different bloom forms based on the arrangement and type of the florets. Forms like the Irregular Incurve feature ray florets that curve upward and inward to create a giant, fluffy globe, completely concealing the center disc florets. In contrast, the Single and Semi-Double forms resemble a classic daisy, with a clearly visible, flat center of disc florets surrounded by only a few rows of ray florets.
Other specialized forms include the Reflexed, where ray florets curve downward in an umbrella-like shape, and the Pompon, which produces small, dense, ball-shaped flowers. The exotic Spider and Quill forms are characterized by long, slender, tubular ray florets that radiate outward, sometimes with a distinctive hook or spoon shape at the tip.
The leaves of the plant are also characteristic, being deeply lobed, often with a slightly velvety underside, and arranged alternately along the stem.
Essential Care and Cultivation
To successfully cultivate chrysanthemums, they require a location that receives full sun, ideally six hours or more of direct light daily. They need rich, well-draining soil because the roots will rot quickly in soggy conditions. When watering, soak the soil deeply at the base of the plant to keep the roots moist while avoiding wetting the foliage, which helps prevent diseases.
A technique called “pinching” is crucial for encouraging the bushy growth habit that produces a greater abundance of blooms. This involves removing about one inch of the tip of each new stem once the plant reaches six to eight inches tall, a process that is repeated every few weeks. Pinching should be continued until early to mid-July, as this stops vegetative growth and signals the plant to begin forming flower buds for its autumn display.
While many garden mums are bred to be hardy perennials in USDA Zones 5 through 9, the varieties sold as autumn decorations are often best treated as annuals in colder regions. For perennial varieties, leaving the dead stems in place over winter provides insulation for the crown. A thick layer of mulch applied after the ground freezes further protects the roots. In very cold climates, the plant can be dug up, potted, and overwintered in a cool, dark, frost-free location.