The genus Cornus, commonly known as dogwood, includes trees and shrubs valued for their ornamental features, such as showy flowers or bracts and vibrant fall color. These plants produce fruit containing seeds, which are the method by which dogwoods naturally propagate. Understanding the characteristics of these seeds and the fruit that surrounds them is key to successful identification and cultivation.
The Visual Characteristics of Dogwood Seeds
Once the fruit pulp is removed, a dogwood seed reveals a hard, woody structure that protects the embryo inside. The seeds are generally small, ranging in length from about 4 to 12 millimeters (0.16 to 0.47 inches), though the size varies by species. They are often described as oval, ellipsoid, or slightly football-shaped, typically having a pale coloration.
The color of the clean seed can be cream, light tan, or pinkish-yellow. A key identifying feature on many dogwood seeds is the presence of distinct longitudinal grooves and ridges running along the length of the seed coat. This textured surface distinguishes them from smooth seeds. The seed coat is robust and hard, contributing to the seed’s dormancy and resistance to germination.
The Fruit That Encloses the Seeds
Dogwood seeds are contained within a type of fleshy fruit known as a drupe. The outer appearance of this fruit varies significantly by species, which aids in identification. For example, the fruit of the common Flowering Dogwood (Cornus florida) is a glossy, oval-shaped drupe, about 1 centimeter long, that turns bright red when ripe in the fall.
The fruit of the Kousa Dogwood (Cornus kousa) is a globose, compound berry that looks like a pink or red sphere, often with a bumpy texture, and can be 2 to 4 centimeters in diameter. Inside the fleshy pulp, the number of seeds is typically low. Flowering dogwood fruit usually contains one to two cream-colored, ellipsoid seeds, although it can hold up to four, while Kousa dogwood fruit contains a few small seeds firmly attached to the pulp.
Preparing Seeds for Propagation
For dogwood seeds to germinate successfully, the surrounding fruit pulp must be completely removed. The pulp contains germination inhibitors that prevent the seed from sprouting and can also promote mold growth during storage. The necessary process involves soaking the collected fruit in water and then rubbing or crushing the material to separate the seeds from the flesh.
Once cleaned and dried, dogwood seeds have a natural mechanism, called dormancy, which must be broken before they will sprout. This is accomplished through a process known as stratification, which simulates the cold, moist conditions of winter. The seeds should be stored in a moist medium, such as damp sand, peat moss, or vermiculite, in a sealed container or plastic bag. This container is then placed in a refrigerator at temperatures around 40 degrees Fahrenheit for an extended period, typically between 90 and 140 days, depending on the species. Following this cold treatment, the seeds are ready to be sown in pots or an outdoor seedbed.